Re: Kernel 2.6.17 and RAID5 Grow Problem (critical section backup)

[Justin Piszcz <jpiszcz@lucidpixels.com>]

On Fri, 7 Jul 2006, Justin Piszcz wrote:

> On Fri, 7 Jul 2006, Justin Piszcz wrote:
>
>> On Fri, 7 Jul 2006, Justin Piszcz wrote:
>> 
>>> p34:~# mdadm /dev/md3 -a /dev/hde1
>>> mdadm: added /dev/hde1
>>> 
>>> p34:~# mdadm -D /dev/md3
>>> /dev/md3:
>>>        Version : 00.90.03
>>>  Creation Time : Fri Jun 30 09:17:12 2006
>>>     Raid Level : raid5
>>>     Array Size : 1953543680 (1863.04 GiB 2000.43 GB)
>>>    Device Size : 390708736 (372.61 GiB 400.09 GB)
>>>   Raid Devices : 6
>>>  Total Devices : 7
>>> Preferred Minor : 3
>>>    Persistence : Superblock is persistent
>>>
>>>    Update Time : Fri Jul  7 08:25:44 2006
>>>          State : clean
>>> Active Devices : 6
>>> Working Devices : 7
>>> Failed Devices : 0
>>>  Spare Devices : 1
>>>
>>>         Layout : left-symmetric
>>>     Chunk Size : 512K
>>>
>>>           UUID : e76e403c:7811eb65:73be2f3b:0c2fc2ce
>>>         Events : 0.232940
>>>
>>>    Number   Major   Minor   RaidDevice State
>>>       0      22        1        0      active sync   /dev/hdc1
>>>       1      56        1        1      active sync   /dev/hdi1
>>>       2       3        1        2      active sync   /dev/hda1
>>>       3       8       49        3      active sync   /dev/sdd1
>>>       4      88        1        4      active sync   /dev/hdm1
>>>       5       8       33        5      active sync   /dev/sdc1
>>>
>>>       6      33        1        -      spare   /dev/hde1
>>> p34:~# mdadm --grow /dev/md3 --raid-disks=7
>>> mdadm: Need to backup 15360K of critical section..
>>> mdadm: Cannot set device size/shape for /dev/md3: No space left on device
>>> p34:~# mdadm --grow /dev/md3 --bitmap=internal --raid-disks=7
>>> mdadm: can change at most one of size, raiddisks, bitmap, and layout
>>> p34:~# umount /dev/md3
>>> p34:~# mdadm --grow /dev/md3 --raid-disks=7
>>> mdadm: Need to backup 15360K of critical section..
>>> mdadm: Cannot set device size/shape for /dev/md3: No space left on device
>>> p34:~#
>>> 
>>> The disk only has about 350GB of 1.8TB used, any idea why I get this 
>>> error?
>>> 
>>> I searched google but could not find anything on this issue when trying to 
>>> grow the array?
>>> 
>>> 
>>> -
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>>> 
>> 
>> Is it because I use a 512kb chunksize?
>> 
>> Jul  7 08:44:59 p34 kernel: [4295845.933000] raid5: reshape: not enough 
>> stripes.  Needed 512
>> Jul  7 08:44:59 p34 kernel: [4295845.962000] md: couldn't update array 
>> info. -28
>> 
>> So the RAID5 reshape only works if you use a 128kb or smaller chunk size?
>> 
>> Justin.
>> -
>> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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>> 
>
>> From the source:
>
> /* Can only proceed if there are plenty of stripe_heads.
> @@ -2599,30 +2593,48 @@ static int raid5_reshape(mddev_t *mddev,
> * If the chunk size is greater, user-space should request more
> * stripe_heads first.
> */
> - if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
> + if ((mddev->chunk_size / STRIPE_SIZE) * 4 > conf->max_nr_stripes ||
> + (mddev->new_chunk / STRIPE_SIZE) * 4 > conf->max_nr_stripes) {
> printk(KERN_WARNING "raid5: reshape: not enough stripes. Needed %lu\n",
> (mddev->chunk_size / STRIPE_SIZE)*4);
> return -ENOSPC;
> }
>
> I don't see anything that mentions one needs to use a certain chunk size?
>
> Any idea what the problem is here?
>
> Justin.
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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>

Neil,

Any comments?

Justin.