Growing a RAID5 array – MDADM
With the release of kernel 2.6.17, there’s new functionality to add a device (partition) to a RAID 5 array and make this new device part of the actual array rather than a spare.
I cam across this post a while ago on the LK list.
LKML: Sander: RAID5 grow success (was: Re: 2.6.16-rc6-mm2)
So I gave it a go. My HOME directory is mounted on a 3×70gb SCSI RAID5 array. so I tried adding a further drive.
Although with the release of mdadm > 2.4 the only real critical part of the process is safer (it backs up some live data that is being copied), I didn;t fancy risking growing a mounted array. So I did plenty of backups, then switched to single user run level.
Basically the step includes adding a disc to the array as a spare, then growing the array onto this device.
mdadm --add /dev/md1 /dev/sdf1
mdadm --grow /dev/md1 --raid-devices=4
This then took about 3 hours to reshape the array.
The filesystem the needs to be expanded to fill up the new space.
fsck.ext3 /dev/md1
resize2fs /dev/md1
I then remounted the drive and wahey. Lots extra space….! Cool or what
EDIT It’s over 18 months since I wrote this post, and Linux kernel RAID and mdadm have continued to move on. All the info here is still current, but as extra info check out the Linux Raid wiki.
Excellent stuff. It inspired me to grow my 3×400GB by one drive. Here’s the result:
[root@coruscant ~]# mdadm --add /dev/md1 /dev/sde1
[root@coruscant ~]# mdadm --grow /dev/md1 --raid-devices=4
[root@coruscant ~]# cat /proc/mdstat
[>....................] reshape = 0.0% (166656/390708736) finish=1347.2min speed=4830K/sec
:
[root@coruscant ~]# cat /proc/mdstat
Personalities : [raid1] [raid5] [raid4]
md2 : active raid5 sde1[3] sdd1[1] sdf1[2] sdc1[0]
1172126208 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
:
[root@coruscant ~]# pvdisplay
:
PV Size 745.21 GB / not usable 0
:
[root@coruscant ~]# pvresize /dev/md2
Physical volume "/dev/md2" changed
1 physical volume(s) resized / 0 physical volume(s) not resized
[root@coruscant ~]# pvdisplay
:
PV Size 1.09 TB / not usable 0
:
[root@coruscant ~]# df -BMB /dev/mapper/VG1-LV0
Filesystem 1MB-blocks Used Available Use% Mounted on
/dev/mapper/VG1-LV0 105690MB 7894MB 92428MB 8% /mnt/backup
[root@coruscant ~]# lvresize -L +10G /dev/VG1/LV0
Extending logical volume LV0 to 110.00 GB
Logical volume LV0 successfully resized
[root@coruscant ~]# ext2online /dev/VG1/LV0
ext2online v1.1.18 - 2001/03/18 for EXT2FS 0.5b
[root@coruscant ~]# df -BMB /dev/mapper/VG1-LV0
Filesystem 1MB-blocks Used Available Use% Mounted on
/dev/mapper/VG1-LV0 116259MB 7894MB 102460MB 8% /mnt/backup
Reshaping the raid took almost 24 hours! But in the end everything just worked – online.
July 15th, 2006 at 9:21 am. Permalink.
I added another 300GB drive to my 4×300GB RAID5. It worked great!
Keep in mind you have to enable the experimental kernel option before mdadm will let you grow your RAID5.
The reason it took almost 24 hours for Frode is probably because of the minimum reconstruction speed configured. Mine was looking like it would take 30+ until I bumped it up by doing “echo 25000 > /proc/sys/dev/raid/speed_limit_min”. After that it ran for about 9 hours.
Then I used xfs_growfs, worked like a charm!
I’m really happy Linux is getting mature with great options like this.
August 2nd, 2006 at 9:07 am. Permalink.
Oh, I should mention that I also had to do “echo 1024 > /sys/block/md0/md/stripe_cache_size” before mdadm would let me grow the array. The mdadm maintainer said a future version would do this automatically. If you’re having an error trying to grow it, check dmegs, if it says the stripe cache is too low you need to change the number (mine said it needed at least 1024) and run that command. You should also replace md0 with your device name.
August 2nd, 2006 at 9:09 am. Permalink.
> I’m really happy Linux is getting mature with great options like this.
I’m pretty pleased too. The Linux kernel is pretty dammed good at the moment. For another project I’m setting myself a MythTV HTPC box. All the hardware had decent drivers in the kernel.. Well apart from a crappy Linksys WMP54GS card I should never have bought!!
August 2nd, 2006 at 6:02 pm. Permalink.
Dears:
I couldn’t use pvresize while the RAID is reshaping. Is there any method to enhance this limitation ?
Thanks
Jack
August 3rd, 2006 at 7:38 am. Permalink.
[...] Growing RAID 5 volumes with mdadm posted by Jonny | at 5:48pm on November 23rd 2006 Category: Computing, Linux | | [...]
November 23rd, 2006 at 6:48 pm. Permalink.
Well, I copied all my DVDs to the RAID and now it’s full again. So I’m adding another disk, up to 6 now. I’m getting 14MB/s reconstruction and it’s telling me it will take around 6 hours.
Jack, I’m pretty sure the new space doesn’t become available until the reshape is finished. It would be theoretically possible to provide it, but accessing it would be very slow, and it’s extra complexity the RAID system doesn’t need. Use the method I mention above to speed it up, and just wait until it’s finished.
November 29th, 2006 at 8:50 pm. Permalink.
Just in case there is Ubuntu readers, they need to know that RAID5 array reshaping is disabled in the stock kernels, giving an “invalid argument” error when trying to grow the array. So they need to compile a custom kernel and enable the option CONFIG_MD_RAID5_RESHAPE=y in the .config file. Note that kernel 2.6.17 or above is required.
January 16th, 2007 at 2:03 pm. Permalink.
hi Muganor,
thanks for commenting. Is that just a Ubuntu thing, or a Debian thing in general?
January 16th, 2007 at 3:05 pm. Permalink.
Hello, thanks for the post, I’m realy excited and going to try to add 5th 250GB disk to RAID5.
So theoretically everything can be done without losing data on the raid, yes? I was thinking, can I do the reshape working in normal mode, just umount’ing /dev/md0 ?
Can I add 2 devices at a time?
mdadm –add /dev/md0 /dev/hdc
mdadm –add /dev/md0 /dev/hdd
mdadm –grow –raid-devices=6 (assuming, that before there were 4 of them)
or should I add one device at a time?
Are there any requirements for the resize2fs version? I have 1.38 on my system. Looks that there’s newer version available.
Thanks!
January 18th, 2007 at 10:10 pm. Permalink.
I just unmounted the RAID device. Apparently this can be done with the device still mounted. But it sounds a bit risky to me!!
Personally I would add a single device at a time. But the functionality has been improving, and it might be fine to add two at a time. You might want to ask on the linux-Raid list. Or do more searching around.
January 19th, 2007 at 10:05 am. Permalink.
I’m in the process of adding a 5th drive to my 4 drive RAID5 array. My root partition is on the array, so everything’s still mounted. I haven’t seen any problems yet. Disk access is a lot slower than normal, but that makes sense because it’s rewriting the whole drive. It’s only 10% done, so we’ll see if it gets through the whole reshape without problems.
January 21st, 2007 at 2:24 am. Permalink.
It just finished adding the 5th drive. Everything still seems to be running okay.
January 21st, 2007 at 6:57 am. Permalink.
[...] Papildus informāciju par šo var smelties: scotgate.org RAID5 grow success [...]
January 23rd, 2007 at 8:55 am. Permalink.
Does it makes any difference to do fsck BEFORE growing to check whether everything is ok with fs?
March 1st, 2007 at 12:49 pm. Permalink.
Does it make any difference to do fsck BEFORE growing to check whether everything is ok with fs?
March 1st, 2007 at 12:50 pm. Permalink.
Not sure. But it cannot hurt to ensure that the filesystem is good.
March 1st, 2007 at 1:43 pm. Permalink.
Just started to reshape
[>....................] reshape = 1.5% (3676288/244195840) finish=459.6min speed=8719K/sec
Will let you know tomorrow how it ends. I’m going to add 2 disks to existing 4 drive raid5, but I’m little superstitious and will do it one at a time. Thanks a lot for the post!
March 1st, 2007 at 7:15 pm. Permalink.
Good luck!!!!
March 1st, 2007 at 8:34 pm. Permalink.
First grow went like a charm, now second is in progress, looks ok.
March 2nd, 2007 at 10:59 am. Permalink.
The second one didn’t go as smooth as first one, but everything turned out ok. After reshape had finished, I did fsck /dev/md0 – and it said that file system is clean, so I executed resize2fs -p /dev/md0 which said that filesystem actually isn’t clean and I should rund fsck -f /dev/md0. I ran with force flag and then ran the resize2 and that’s it – everything looks good to me. So I growed RAID5 from 4 to 6 disks in 2 steps (took about 8-9hours for each 250G 7200 disk to reshape, ~30min fsck, ~30min resize2s). NICE!
March 2nd, 2007 at 9:43 pm. Permalink.
Is it possible to speed up the build process. I have just created RAID5 4×250G.
March 23rd, 2007 at 11:25 pm. Permalink.
You can change the value that is in the proc filesystem for that raid device:
e.g.
echo 400000 >/proc/sys/dev/raid/speed_limit_max
That will increase the maximum speed at which it will sync. Obviously if you are already running at the maximum, it will not help. Good luck.
March 24th, 2007 at 9:53 am. Permalink.
What kind on speed should I get with dual P3 733. At the time it is going 890K/Sec
March 24th, 2007 at 11:21 am. Permalink.
Thanks heaps for this guide, you’re a lifesaver! Got my array reshaping right now, adding a 5th disk.
md1 : active raid5 hda1[4] sdb1[3] hdg1[2] hde1[1] hdc1[0]
234420096 blocks super 0.91 level 5, 64k chunk, algorithm 2 [5/5] [UUUUU]
[>....................] reshape = 3.6% (2837120/78140032) finish=161.9min speed=7748K/sec
bitmap: 0/150 pages [0KB], 256KB chunk
April 4th, 2007 at 10:13 am. Permalink.
[...] Then came adding another 80gb drive to the array. A bit of Googling found this excellent howto on adding a spare drive to a software RAID 5 setup, extending it to the spare drive, and extending the filesystem to fit. About 2 hours later, it was all done. Couldn’t be easier. [...]
April 4th, 2007 at 4:14 pm. Permalink.
Would it be a similar step for adding drives to a linear RAID you think?
April 7th, 2007 at 11:56 am. Permalink.
I Don’t know I’m afraid. Probably not. I saw your posts and replies on the LinuxRaid mailing list. A better source of knowledge than me!!!
Cheers
Ferg
April 9th, 2007 at 3:19 pm. Permalink.
To 3 x 500GB I added one disk (second is waiting in line
, reshaping took 9h 47min
Speed was between 12000 and 14000KB/s
It all depends on size of disks and whole array,
as bigger the size, as longer it take.
Thanks for the info how to do it, man pages on mdadm are…. manpages
April 16th, 2007 at 8:06 am. Permalink.
[...] Expanding RAID? Sure can do, but the ‘reshaping’ can be quite slow =) RedHat.com, Ferg’s gaff. [...]
May 3rd, 2007 at 1:08 pm. Permalink.
looks like Ubuntu Feisty’s server kernel has the correct options to start re-shaping without re-compiling the kernel.
root@tank:~# cat /boot/config-2.6.20-15-server |grep CONFIG_MD_RAID5_RESHAPE
CONFIG_MD_RAID5_RESHAPE=y
root@tank:~#
May 12th, 2007 at 9:17 am. Permalink.
Thanks for the useful resource/howto.
I have grown my existing raid 5 array at home from 3 to 4 disks, having several md partitions on each disk for /var, /usr, etc. I’m running Debian 4 with an array that was created several years ago.
In my experience, running grow on a live system can lead to the file system being partially unavailable. For /home I could stop services using it, umount, fsck, resize2fs and move along. Doing this operation on /usr and /var partitions required going to init 1. Doing it on / caused me to have a system that had no access to commands init, reboot, halt, nor response to Ctrl+Alt+delete. I was at init 1 anyway so I used the power button and it rebooted fine.
For production system, I would not use mdadm –grow unless it was a partition not a part of the OS and I could turn off the services on it while these steps are taken. I’m sure in years to come this will improve.
The Software Raid Howto page at the Linux Documentation Project is now very out of date so I expect this page will have more visitors.
May 18th, 2007 at 11:01 am. Permalink.
Hi Donald,
thanks for the comments. I only tried this on an umounted partition. Which was fairly easy due to it being my HOME partition.
There’s a few other useful RAID resources. None more useful than the linux-Raid mailing list.
http://vger.kernel.org/vger-lists.html#linux-raid
It’s fairly low traffic. I would guess around about 40 posts a week (that is a very, very rough guess). There may be a digest version.
May 18th, 2007 at 11:10 am. Permalink.
Hi,
Something wrong with my debian based Storage server. I have compiles new kernel with raid5 add disk “setting”
Drive failed after my kernel upgrade. kernel version 2.6.21.1 Debian 4,0 Etch.
Still I get this error:
i# mdadm –add /dev/md0 /dev/hdk1
mdadm: add new device failed for /dev/hdk1 as 3: Invalid argument
I have 3 disk array witch off one drive has failed.
May 23rd, 2007 at 1:48 pm. Permalink.
I can only guess that either your MD device or the SCSI device is wrong. If not try removing the failed device and re-adding the new device to the array.
If upgrading the kernel has caused you grief, I would also suggest you go back to the last workign kernel, until all is well again.
Good luck!
May 23rd, 2007 at 2:44 pm. Permalink.
I added the failed device back to array, worked just fine. All HD’s are connected to IDE controllers, Promise chipset.
May 23rd, 2007 at 5:01 pm. Permalink.
Nice one!!
May 24th, 2007 at 10:17 am. Permalink.
Could someone check these SMART outputs. I used webmin and smartmontool.
Drive I can’t add to array
http://pastebin.ca/507188
Error:
sudo mdadm –manage /dev/md0 –add /dev/hdk1
mdadm: add new device failed for /dev/hdk1 as 3: Invalid argument
Drive that drops from array at boot. http://pastebin.ca/507185
May 24th, 2007 at 2:04 pm. Permalink.
Heya, thanks a bunch for this howto. I’m running a 6x 500g array (coming from 3×500 in one go!). The only thing I did differently was that I put LVM2 in between the array and the filesystem. This way I can steal some extra space from a (hardware) raid 1 set that’s also in the system (has root, swap, etc. on it but still 250G free space… would’t want to waste them).
Very neat that raid5 resizing now works with sw raids as well! – saved me a bundle on an hw controller there.
May 24th, 2007 at 3:54 pm. Permalink.
No problem. Glad it was of some use! Have a look at the Linux-Raid mailing list to see just how well MDADM and Linux kernel software raid is coming on!
May 24th, 2007 at 4:31 pm. Permalink.
I’d been waiting for this functionality for years, and was very psyched when 2.6.17 came out. I just had occasion to make use of it for the first time, went from 4×320GB to 5. Left everything mounted and network services running, all worked okay even with continuous accesses to the array. RIP raidreconf.
June 8th, 2007 at 2:13 pm. Permalink.
MDADM truly rocks for anything Linux software related. Neil Brown deserves a medal for writing this.
June 8th, 2007 at 2:54 pm. Permalink.
I also have this strange error from mdadm … add new device failed. I copied the partition table with dd. and added the hdc2 to md2 and now I can’t add hdc3 to md3 ?!?!?! Very strange.. Anyone an idea ?
July 7th, 2007 at 12:12 pm. Permalink.
Guys, thought this might help.
You need to create a blank partition first, and then set the ‘raid’ flag on the drive. You can do this through gparted.
Then add it with the mdadm –add
July 23rd, 2007 at 11:48 am. Permalink.
Oooh guys. Careful when adding drives like this. I just lost 3 hours trying to find what was going on.
When you resize your raid, make sure you edit your /etc/mdadm.conf file to update the number of devices in your raid configuration!
Otherwise you reboot and poof, ur raid is gone
At least this happened to me on Fedora Core 7.
Stupid thing fails on boot and goes to this “Repair filesystem” thingy because it can’t mount /dev/”insert your lvm or fs here”.
The anoying thing is, the Repair Filesystem mount’s your root readonly!
To get your / writeable:
mount -w -o remount /
Then edit your /etc/mdadm.conf to the new number of drives in your configuration.
Or alternatively, edit your /etc/fstab and take out the line that mounts your raid (then you can fix it later).
July 25th, 2007 at 12:22 pm. Permalink.
As long as each member of the array has the partition type set to FD – Raid autodetect, then you should not have to update mdadm.conf. The MD driver should autodetect, assemble and start each array.
You mention that the ROOT was mounted read only. This cannot have been a RAID5 device, as to the best of my knowledge you can only boot from a RAID1 array. IS that true?
Cheers
July 25th, 2007 at 1:30 pm. Permalink.
I am not booting from the raid. I have another drive in my pc seperate from raid that is running the linux.
Can you explain a little more about this FD partition type.
I have my raid drives formatted as a blank partition, and then i have set the flags ‘boot’, and ‘raid’, on each partition. This is also in fact how DiskDruid creates ’software raid’ partitions.
And yes, mdadm auto-detects the drives, but only up until the number of devices that is specified in /etc/mdadm.conf
DEVICE partitions
MAILADDR root
ARRAY /dev/md0 level=raid5 num-devices=6 uuid=46e9ab9d:c365cd2c:e08c1bc3:73c070ca
maybe, if the ‘num-devices=6′ was removed entirely, then it would detect the drives fine. I will try that.
It is also possible to specify which drives you want in your array specifically i.e.
ARRAY /dev/md0 level=raid5 num-devices=6 uuid=46e9ab9d:c365cd2c:e08c1bc3:73c070ca devices=/dev/sdb1,/dev/sdc1,/dev/sdd1,/dev/sde1,/dev/sdf1,/dev/sdg1
if you specify like this, then the config will ignore any drives not in the devices list.
July 29th, 2007 at 3:44 am. Permalink.
I’ve just successfully completed the RAID growth of my 3×500GB RAID5. It’s now 4×500GB, and it took something about a full day, including filesystem-check and resize.
August 8th, 2007 at 6:33 pm. Permalink.
I’m actually doing the same thing now with Ubuntu 7.04 — expanding a 3×500GB RAID5 to 4×500GB.
The grow took about 12 hours. I ran fsck.ext3 with no issue, but when I went to run resize2fs it said, “Please run ‘e2fsck -f /dev/md0′ first”. Did you have to do this, Daniel?
That’s where I am now… the first time I ran it my ssh connection was dropped. Wasn’t listed as a process when I relogged in, so I ran it again. We’ll see how it goes…
- Som
August 23rd, 2007 at 1:17 am. Permalink.
Well, I wasn’t able to run e2fsck from over ssh — the connection kept dropping.
I went home and ran it directly on the box. Everything worked great.
So, as a recap:
Ubuntu 7.04 (Feisty Fawn)
3×500GB grown to 4×500GB
mdadm –add /dev/md0 /dev/sde1
mdadm –grow /dev/md0 –raid-devices=4
(~12 hours)
e2fsck -f /dev/md0
(~15 minutes)
resize2fs /dev/md0
(~10 minutes)
- Som
August 23rd, 2007 at 6:59 pm. Permalink.
Hi, You might want to investigate Screen if you have an dodgy connection. You can keep a persistent session going with it. If your connection drops, you can start screen again and pick up the session where it drops.
August 23rd, 2007 at 7:10 pm. Permalink.
I didn’t have putty set to send null packets to maintain connections. Just changed it… will see if it helps. I’ll check out screen, though… thanks!
- Som
August 31st, 2007 at 9:05 pm. Permalink.
[...] as you maybe know, I do use linux software raid to store all my data. now i bought a new 500gb western digital drive and added it to my existing raid5 array which is made of 3 drives like the new one (information on growing came from this site). I already thought that this might be a longer task, but I didn’t think it would take this long; md3 : active raid5 sdd1[3] sdc1[2] sdb1[1] sda1[0] 976767872 blocks super 0.91 level 5, 64k chunk, algorithm 2 [4/4] [UUUU] [>………………..] reshape = 0.4% (2237184/488383936) finish=977.7min speed=8286K/sec [...]
September 9th, 2007 at 12:20 pm. Permalink.
hmm ok, im getting a Hardware RAID Controller that can grow the RAID5 Array. am I right with this:
Ill need to use lvm in order to grow the partitions and the expand the filesystem ?
September 20th, 2007 at 12:09 am. Permalink.
You may be able to grow the RAID5 array with your hardware RAID controller, but I know nothing about this. This post was about using the Software MD RAID driver in the Linux kernel, and using the RAID utility MDADM to grow the array.
September 20th, 2007 at 8:17 am. Permalink.
[...] Post de un guiri en su blog con bastantes comentarios interesantes. Hilo en Ubuntu Forums sobre el tema. [...]
September 27th, 2007 at 12:39 pm. Permalink.
I have just grown a raid 6 array from 6 to 8 disks on an alpha of Ubuntu 7.10, no real problems.
The kernel is an ubuntued 2.6.22.
Pretty much as listed here, I added the two drives as spares then grew the raid onto them.
Also updated the mdadm.conf since I specify the array by devices. I’ve removed the two new drives and re-added them too. Interestingly, although I add them both at once, it rebuilt onto one disk then rebuilt onto the other. I can only assume that this is a holdover from raid 5.
The LVM had to be resized on top and the JFS filesystem unmounted and then remounted/resized.
Rebuilding was on the order of 2 hours @ 65 meg / sec with no tweaking.
September 29th, 2007 at 5:39 pm. Permalink.
Spares, Spares every wherez!
Quick Q:
Does a spare need to be configured to be EXACTLY like the other drives in the array? I want 1 drive to serve as a spare for 2 arrays 1 is ~300GB raid 1 the other is 500GB raid 5.. can i just partition the whole drive and it’ll use what it needs? Thanks!
October 4th, 2007 at 4:00 pm. Permalink.
I’ve addded a 147Gb partition to a RAID10 array with 70Gb partition members. This worked fine. However, I’m not sure for RAID5. I would think it would work, but you might be best testing this before relying on it
October 4th, 2007 at 6:20 pm. Permalink.
Answered my own Q above. It doesn’t need to be the exact size. You are warned it is bigger (wont allow smaller) and the unused space is wasted. Until you can ‘grow’ the array to use it.
BUT Q2 for you all.
Can you remove a drive from an active array? Say you have a 4 drive raid 5 array.. gives you lots of space. you decide you wont need all that space and want a HDD back after all the drives have become active, is it possible to tell it to stop using the drive? maybe shrink the size of each parition and remove a device or something?
October 9th, 2007 at 11:19 am. Permalink.
I don’t think that will work. You’ve two questions. Can you resize the filesystem you’re using, and can MDADM and Grow shrink a raid array. I don’t think either is possible, but I stand to be corrected. Try the LinuxRaid mailing list.
October 9th, 2007 at 11:32 am. Permalink.
Well you can shrink *some* file systems – like ext3 which is the one i am using. Although i believe you cant shrink the likes of xfs.
October 9th, 2007 at 11:49 am. Permalink.
Hi, me again!
Question for you and your viewer/readers..
I have noticed that 1 of the 2 drives in my mirrored array is always reporting to be a couple of degrees hotter than the other.
Is this because (possibly) it is the primary drive and is used for all the reads as well as writes?
Any suggestions?
November 5th, 2007 at 5:37 pm. Permalink.
Well… I’ve got the itch to add another 500gig drive to my three drive RAID5 array. Problem is that I have noplace to backup the ~1TB of data on the RAID. How risky is this process? This is a fresh Debian lenny installation.
November 19th, 2007 at 10:16 am. Permalink.
Thanks for the help , I am adding 2×750Go one by one to my 3×750Go RAID 5 device . It will take more than 24hours minimum but it works !!!
November 19th, 2007 at 10:20 am. Permalink.
Thank you very much for this. I’m currently putting together a 7*500GB NAS with debian and RAID5. This information came in very handy because five of those disks are formatted as NTFS. Cheers, mate!
November 25th, 2007 at 12:54 pm. Permalink.
No Problem. Glad it was of use.
Cheers
November 25th, 2007 at 5:02 pm. Permalink.
Anyone know what the Software raid 5 limit is size wise and disk wise?
Ie. Is there a 5TB Limit, 2TB limit?
Do you need a certain amount of memory to go past 2TB… After X Drives the Array becomes unstable…
November 30th, 2007 at 9:09 pm. Permalink.
Thanks for this! I am about 21% complete on rebuilding from 4 to 6 500Gb SATAII drives in a single step, and your article has been brilliant.
I’m amazed at how resilient this is – although I probably wouldn’t recommend it, I was watching a movie streamed from this raid array, copying data to it *and* growing at the same time.
Awesome.
December 1st, 2007 at 12:45 am. Permalink.
This array originally built using Debian Etch
OS is not on the array.
Hardware is/will be 10 half terrabyte Maxtor sataII discs
Configured as raid6
Mounted two in icybox 5 disc sata disc racks.
Connected by three no-name sii quad port sata drive controllers.
5 drives actually configured. Number 6 installed.
Could not grow the number of devices in the array using Etch (kernel too old)
OS deleted and replaced by Ubuntu 7.04 (desktop actually)
Installed mdadm and:
root@Beijun:/# uname -a
Linux Beijun 2.6.22-14-generic #1 SMP Sun Oct 14 23:05:12 GMT 2007 i686 GNU/Linux
root@Beijun:~# mdadm –assemble /dev/md0
mdadm: failed to add /dev/sde1 to /dev/md0: Invalid argument
mdadm: /dev/md0 has been started with 5 drives.
root@Beijun:/# fdisk /dev/sde
The number of cylinders for this disk is set to 60801.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help): p
Disk /dev/sde: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0×00000000
Device Boot Start End Blocks Id System
/dev/sde1 1 60801 488384001 83 Linux
Command (m for help): q
root@Beijun:/# mdadm –add /dev/md0 /dev/sde
mdadm: added /dev/sde
root@Beijun:/# mdadm –grow /dev/md0 –raid-devices=6
mdadm: Need to backup 768K of critical section..
mdadm: … critical section passed.
root@Beijun:/#
/dev/md0: 1397.28GiB raid6 6 devices, 0 spares. Use mdadm –detail for more detail.
root@Beijun:/# mdadm –query –detail /dev/md0
/dev/md0:
Version : 00.91.03
Creation Time : Tue Nov 20 00:26:12 2007
Raid Level : raid6
Array Size : 1465159488 (1397.29 GiB 1500.32 GB)
Used Dev Size : 488386496 (465.76 GiB 500.11 GB)
Raid Devices : 6
Total Devices : 6
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Thu Dec 13 23:01:44 2007
State : clean, recovering
Active Devices : 6
Working Devices : 6
Failed Devices : 0
Spare Devices : 0
Chunk Size : 64K
Reshape Status : 2% complete
Delta Devices : 1, (5->6)
UUID : a562da4a:8beaefd3:ed4e5664:d2029d2e
Events : 0.7860
Number Major Minor RaidDevice State
0 8 96 0 active sync /dev/sdg
1 8 32 1 active sync /dev/sdc
2 8 16 2 active sync /dev/sdb
3 8 48 3 active sync /dev/sdd
4 8 80 4 active sync /dev/sdf
5 8 64 5 active sync /dev/sde
Absolutely bl**dy marvelous software.
Thanks for the hints, the man page lacks somewhat in detail.
Cheers Harry
December 14th, 2007 at 12:18 am. Permalink.
hi,
it’s really a cool thing, but how do u connect the drives?
i’ve looked for some cheap sata hba’s but i couldn’t find some exept Promise SATA300 TX4 – but it doesn’t let u read out the s.m.a.r.t. infos ;(
greets Stefan
January 22nd, 2008 at 12:17 am. Permalink.
I made a mistake and ran:
mdadm -add /dev/md0 /dev/sdd
instead of :
mdadm -add /dev/md0 /dev/sdd1
then I ran the grow command. Is this going to be a problem?
January 26th, 2008 at 5:26 am. Permalink.
I once did the same and created an entire array from the raw block devices rather than the partitions. It did not cause any problems for me. Too be honest I\m not too sure what the real ramifications are. Why not swap out the disc when you have some time, repartition the drive and re add it except as a partition instead?
January 26th, 2008 at 11:22 am. Permalink.
Ah, just got done adding FOUR 500 gig drives to bring my total to EIGHT 500 gig drives. Added them one by one without having them mounted. Had to do e2fsck -f before I resized it. Last drive too over 40 hours to add and another 2 hours to resize. Now have 3.36 TB space avail.
Thanks Ferg!
-stile
January 31st, 2008 at 11:11 pm. Permalink.
happy to be of some help. Proper kudos goes to Neil Brown the MDADM developer though! Check out the Linux Raid mailing list for some even better cool stuff.
February 1st, 2008 at 12:43 am. Permalink.
Thanks for the great information!
Question: anyone know what will happen if power is lost or a drive fails during the reshape part of “grow”?
February 8th, 2008 at 12:49 am. Permalink.
Nice info, thanks. All we need next is an update to mdadm’s handling of bad blocks.
February 13th, 2008 at 6:42 pm. Permalink.
[...] Eine gute Anleitung findet sich auch auf der Seite Ferg’s Gaff. [...]
February 24th, 2008 at 3:20 pm. Permalink.
I would like to create a raid1 volume from an existing single volume that isn’t a lvm volume…
how can I add the existing disk to be in a lvm disk group with another disk to be a raid1. Basically I’m looking to create a mirror to migrate data to another location.
February 25th, 2008 at 2:38 am. Permalink.
I am a complete noob with Linux… but am using Software Raid5 over Windows Server 2003 just because of how slow and limited it was.
Took 22 hours to expand my 3 x 750 array to 4 drives… check the file system and expand it…
Even those this guide was super-simple, it was all I needed. Although I had to do a few things different (Ubuntu) it worked out in the end.
Thanks, I’ll probably come back to this site when I have to expand with more 750 drives… I’ve already forgotten the commands
February 28th, 2008 at 1:21 am. Permalink.
Great. Glad it was of use!
Have a look at the newly revamped Linux RAID wiki for more updated info
http://linux-raid.osdl.org/index.php/Main_Page
February 28th, 2008 at 10:03 am. Permalink.
[...] Growing a RAID 5 array Blog post which describes using mdadm to grow a RAID 5 array to include more disk space. [...]
March 31st, 2008 at 4:53 pm. Permalink.
Hey guys, I grew my RAID5 from 3×300gb to 4×300gb. This drive (/dev/md2) was mounted as root filesystem, with a small raid0 for the /boot partition and lilo as bootloader. anyway, it won’t boot anymore after the grow…
Lilo seems to load from the /boot partition, but after some time during the boot process it just says:
md: md2 stopped.
Do I have to tell lilo somehow that the md2 disk is bigger now? I think that is the problem, but i don’t know how to do it…
thanks for any suggestions!
samuel
April 16th, 2008 at 9:31 am. Permalink.
Hi Guys, I have just grown my raid 5 from 7 to 8 500Gb drives.
I am now running into this problem.
When I try to run fsck /dev/md0
fsck.ext2: Device or resource busy while trying to open /dev/md0
Filesystem mounted or opened exclusively by another program?
Or when I try to run resize2fs /dev/md0
resize2fs: Device or resource busy while trying to open /dev/md0
Couldn’t find valid filesystem superblock.
Cat /proc/mdstat outputs:
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb1[0] sdi1[7] sdg1[6] sdh1[5] sdf1[4] sde1[3] sdd1[2] sdc1[1]
3418686208 blocks level 5, 256k chunk, algorithm 2 [8/8] [UUUUUUUU]
unused devices:
However, I can still access and mount my filesystem – i just cannot grow it, which I find very strange.
I have tried to init 1, to go to single user mode, and I have made sure file system is unmounted, but this ‘busy’ error still occurs.
Any ideas? I’m kinda stuck. Google is no help…
June 2nd, 2008 at 2:55 pm. Permalink.
Hi Jeremy, I’m afraid I’ve no idea. I saw your post on the Linux Raid list. I’m sure you’ll get a decent response on their. BTW I replied to your email address but it bounced. Is it not asdf@asdf.com?
June 2nd, 2008 at 8:59 pm. Permalink.
hehe i feel a bit silly.
Since I am using LVM, all I had to do was 1:
PVresize.
2. using system-config-lvm just increase to use new space
Reason why the ‘busy’ message kept appearing is because LVM has the device locked.
June 6th, 2008 at 1:23 pm. Permalink.
I saw the thread. Easy mistake to make. I’m sure I would have done so!
June 6th, 2008 at 1:33 pm. Permalink.
I have 2×500GB in a RAID 0 array. I have a spare 500GB lying around. Is there a way I can add the spare disk and covert it to RAID 5?
How would I do it?
Daze
June 11th, 2008 at 2:46 pm. Permalink.
I have just expanded a 4 disk raid5 to 6 disk raid5 whilst being online, took roughly 12 hours, worked smoothly
July 27th, 2008 at 10:12 pm. Permalink.
Daze,
Depending on how much data you have on your RAID0 and if it’ll fit on one 500GB.
- add your third disk
- copy all the raid0 data if it’ll fit to the third disk
- break the raid0
- create a mirror/raid1 with the third disk
- then create a raid5 with only 2 disks
- then add the last disk
- then resize the filesystem to use all of the new raid5.
See this reference;
http://scott.wallace.sh/node/1521
September 2nd, 2008 at 2:04 pm. Permalink.
Hi there, I am using a 4×500GB Raid5 and would like to grow it using the described method. *BUT* I am using dm-crypt and no LVM.
Q: Is dm-crypt transparent enough to make the growing possible? Any recommendations or experiences yet?
September 11th, 2008 at 7:33 pm. Permalink.
Hi, thank’s to this howto, I’ve started to reshape my array
md8 : active raid5 sdd8[3] sda8[0] sdc8[2] sdb8[1]
608702464 blocks super 0.91 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
[>....................] reshape = 2.8% (8538112/304351232) finish=344.6min speed=14301K/sec
Hope, everything will be OK.
October 15th, 2008 at 1:41 am. Permalink.
Hey,
I am about to expand my existing 4×500GB raid5 array. It has been a year since i created it and i cant remember exactly what i did. Do you HAVE to create the Linux Raid partition for mdadm? I have vague memories of that not being necessary? (might have been a pure lvm system i read that for)
Also I plan to add 2 new 750GB the plan being that as the existing drives are replaced they will be bigger and eventually all of them will be at least 750GB and i can grow the array. to at least the size of the smallest. Does this sound ok?
Also I had the idea of before i add to the array decommissioning one of the existing 500GB and adding a 750 in its place? Checking it works and then add the 500GB back as a spare to keep wear down. Does this sound crazy or sane?
October 17th, 2008 at 10:47 am. Permalink.
Hi, You do have to create the partition in order to add it to the array. You can add plain block devices, but that becomes less flexible in future.
Check out the Linux raid Wiki
http://linux-raid.osdl.org/index.php/Main_Page
October 17th, 2008 at 10:52 am. Permalink.
[...] Growing RAID 5 volumes with mdadm [...]
October 20th, 2008 at 10:51 pm. Permalink.
Anyone here done much with Consistency Checks and software raid?
October 22nd, 2008 at 3:30 pm. Permalink.
I regularly do the following:
echo check >> /sys/block/md1/md/sync_action
That’s about all.
October 22nd, 2008 at 3:37 pm. Permalink.
That is what i have just read.. and then you can do a repair. I am surprised that mdadm has no feature to automate this. Also, how regularly is regularly?
October 22nd, 2008 at 3:46 pm. Permalink.
Thanks for the Infos!
I`m currently growing
md0 : active raid5 sdd1[4] sda1[0] sdc1[3] sdb1[1]
976767488 blocks super 1.0 level 5, 256k chunk, algorithm 2 [4/4] [UUUU]
[>....................] reshape = 0.9% (4747520/488383744) finish=1071.8min speed=7517K/sec
bitmap: 1/466 pages [4KB], 512KB chunk
unused devices:
October 27th, 2008 at 12:57 pm. Permalink.
[...] der Platten und GBs mit 4 – 10 Stunden rechnen, bis das sog. “Reshape” fertig ist. Ferg hat dafür einen guten Artikel [...]
November 7th, 2008 at 5:21 pm. Permalink.
Returning to this article, thanks for nice info.
Just in case — those running Linux software RAID5 on partitioned disks might badly need understanding of stripe alignment: http://www.pythian.com/blogs/411/aligning-asm-disks-on-linux
November 17th, 2008 at 8:16 pm. Permalink.
Jon H-
Did your test from Oct 17th work? I was thinking about doing something similar. It seem like it should work. The only thing that I question is how happy Linux RAID will be when I add a partition that is bigger than the existing partitions (like adding your 750GB).
According to the Linux RAID Wiki I should be able to size a partition that has the “amount of space [I] will eventually use on all…disks”. But I want to stop short of growing the RAID and use drives in that state until am ready to pull the smaller disks (once all the big disks are procured over time), then grow the RAID at that time. I am aware that the RAID would use only a 500GB portion of the 750GB (hypothetically). But the intent is to be ready for future expansions and ever-increasing drive sizes.
Am I off my rocker? Are we playing with fire?
December 18th, 2008 at 10:19 pm. Permalink.
CHAPS.
Just a quick Q i just did a mdadm –detail md4 to see a state of ‘active’ not ‘clean’ as per my other arrays. any clues what this means?
January 13th, 2009 at 7:22 pm. Permalink.
-quazeye-
I had no problems adding the 750GB’s i just created a linux raid partition on them that is the size of the WHOLE disk, and set the number of raid devices. It then just expanded to include them. I believe that as and when i have replaced the original 4 500GB’s i can set the size to max and it will grow to the new smallest size (750GB) i am closer to doing this than i imagined i would be 18months down the line but hey.
January 13th, 2009 at 7:25 pm. Permalink.
Thanks to this awesome entry, I’m currently adding a 4th 750GB hd to my RAID5. With the age of the system, and the layout of the drives, it says its going to take over a week to resync.
I’m currently at 25.9% and its been running since Sunday the 25th.
January 27th, 2009 at 10:01 pm. Permalink.
hey I had a question about the growth speed. I added a 1.5TB drive to a raid6, only I didn’t change the /proc/sys/dev/raid/speed_limit_minor speed_limit_max before I issued the grow, does it change speeds dynamically? I have about 28 hours left if not (12 hours into it)…
April 3rd, 2009 at 8:10 pm. Permalink.
[...] Update: I just added another two 1TB drives, for a total of five! This article about growing RAID 5 arrays was very helpful. [...]
April 29th, 2009 at 3:51 am. Permalink.
Growing a raid5(6tb->7.5tb):
md_d0 : active raid5 sdg1[5] sdb1[0] sdf1[4] sde1[3] sdd1[2] sdc1[1]
5860543488 blocks super 0.91 level 5, 256k chunk, algorithm 2 [6/6] [UUUUUU]
[====>................] reshape = 22.0% (322644992/1465135872) finish=1875.4min speed=10152K/sec
May 14th, 2009 at 6:49 am. Permalink.
Hey, anyone got any pointers on how big to make the raid partitions? I have a 6 drive array made up of 4×500 and 2×750 in preparation for all drives being grown when i have phased out all the 500GB’s – which is what i am about to do.. switch out a 500GB with a 1TB. But i wonder how large should the raid partition be? I read that all drives vary slightly in block sizes? so i should smooth that over?
August 16th, 2009 at 10:23 am. Permalink.
Jonas I am going from 5tb drives to 6 and am very hesitant, it will be maxing out my space on this mb and hopefully will help with my editing space.
At Jon H that doesn’t look like a raid 5 set up. I was told u are limited by the smallest partition in raid 5 and u don’t want to mix different ones.
Hence why my coming server rack is going to probally go 2tb drive right off so as they come down and i expand I can fill out to the 10 tb mirrored raid I need. Only problem is where to buy WD black 2tb drives they seem to only be coming in green where i shop.
August 20th, 2009 at 5:59 am. Permalink.
Don’t forget to modify mdadm.conf, or the array won’t be detected on the next boot.
October 18th, 2009 at 1:16 pm. Permalink.
[...] Growing a RAID5 array – MDADM [...]
November 4th, 2009 at 8:54 pm. Permalink.
FYI: Updated Linux RAID Wiki Link: http://www.linuxfoundation.org/collaborate/workgroups/linux-raid
January 6th, 2010 at 12:47 am. Permalink.
Just expanded my array from 5×1Tb to 6×1Tb, and it took around 30 hours to finish growing the array. Then the fsck took quite a bit of time (I decided to sleep sometime after 20 minutes or so of watching stage 1… BTW at least on ubuntu, it has to be “fsck -f /dev/md0″, or else it will just say “clean!” and refuse to resize). Finally, the grow took about 3 seconds.
This went more smoothly than I could possibly have imagined… At every stage I was anticipating disaster, but I was pleasantly surprised. Not one error all the way through! Thanks for the simple walkthrough!
February 18th, 2010 at 6:12 pm. Permalink.
Linux Raid Wiki has moved to http://raid.wiki.kernel.org/
March 15th, 2010 at 1:45 am. Permalink.