Raid 5 on Fedora 4 working with SATA ?
Terry Barnaby
terry1 at beam.ltd.uk
Thu Feb 2 10:13:37 UTC 2006
Terry Barnaby wrote:
> Gilboa Davara wrote:
>
>> On Wed, 2006-02-01 at 12:01 +0000, Terry Barnaby wrote:
>>
>>> Gilboa Davara wrote:
>>>
>>>> By default software RAID1/5/6 support on-line drive
>>>> kill/remove/rebuild/etc.
>>>> However, seems that the MD driver is unaware of the dead drive.
>>>>
>>>> What does /proc/mdstat say?
>>>>
>>>> Gilboa
>>>>
>>>>
>>>
>>> After removing the SATA cable on /dev/sdd, if I access a file there
>>> is a long delay
>>> and then the program returns with no error but no data. For example:
>>> "cat /data/test-file" will delay and then exit with status of "0" but
>>> no file
>>> contents are displayed.
>>>
>>> The kernel is: 2.6.14-1.1656_FC4smp: I get the following kernel
>>> messages:
>>>
>>> Feb 1 11:51:37 library kernel: ata2: command 0x35 timeout, stat 0x0
>>> host_stat 0x61
>>> Feb 1 11:51:38 library sshd(pam_unix)[13027]: session opened for
>>> user root by root(uid=0)
>>> Feb 1 11:52:07 library kernel: ata2: command 0x25 timeout, stat 0x0
>>> host_stat 0x61
>>> Feb 1 11:53:07 library last message repeated 2 times
>>> Feb 1 11:54:37 library last message repeated 3 times
>>> Feb 1 11:55:01 library crond(pam_unix)[13091]: session opened for
>>> user root by (uid=0)
>>> Feb 1 11:55:01 library crond(pam_unix)[13091]: session closed for
>>> user root
>>> Feb 1 11:55:07 library kernel: ata2: command 0x25 timeout, stat 0x0
>>> host_stat 0x61
>>>
>>> /proc/mdstat has:
>>> Personalities : [raid1] [raid5]
>>> md1 : active raid1 sdc1[0]
>>> 20482752 blocks [2/1] [U_]
>>>
>>> md2 : active raid5 sdd3[3] sdc3[2] sdb3[1] sda3[0]
>>> 873196800 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
>>>
>>> md0 : active raid1 sdb1[1] sda1[0]
>>> 20482752 blocks [2/2] [UU]
>>>
>>> unused devices: <none>
>>>
>>> The output of "mdadm -Q --detail /dev/md2" is:
>>> /dev/md2:
>>> Version : 00.90.02
>>> Creation Time : Tue Jan 31 14:14:07 2006
>>> Raid Level : raid5
>>> Array Size : 873196800 (832.75 GiB 894.15 GB)
>>> Device Size : 291065600 (277.58 GiB 298.05 GB)
>>> Raid Devices : 4
>>> Total Devices : 4
>>> Preferred Minor : 2
>>> Persistence : Superblock is persistent
>>>
>>> Update Time : Wed Feb 1 11:51:07 2006
>>> State : active
>>> Active Devices : 4
>>> Working Devices : 4
>>> Failed Devices : 0
>>> Spare Devices : 0
>>>
>>> Layout : left-symmetric
>>> Chunk Size : 64K
>>>
>>> UUID : 56bd5037:9d9b9018:eb8f01d6:94155776
>>> Events : 0.230
>>>
>>> Number Major Minor RaidDevice State
>>> 0 8 3 0 active sync /dev/sda3
>>> 1 8 19 1 active sync /dev/sdb3
>>> 2 8 35 2 active sync /dev/sdc3
>>> 3 8 51 3 active sync /dev/sdd3
>>>
>>> Terry
>>
>>
>>
>> Very weird.
>> I've got a number of both IDE, SATA and SCSI RAID5 setups and I never
>> seen such a problem.
>> What happens if you try to access the RAID5 array?
>> (hdparm -tT /dev/md2)
>>
>> Gilboa
>>
>
> I hav'nt tried "hdparm -tT /dev/md2", but if I access a file there is a
> long delay
> and then the program returns with no error but no data. For example:
> "cat /data/test-file" will delay and then exit with status of "0" but no
> file
> contents are displayed.
>
> This is VERY VERY BAD !
>
> I really think this must be a bug, possibly in the SATA driver in Fedora
> Core 4's
> 2.6.14-1.1656_FC4smp kernel. I have a spare SCSI system with 3 SCSI disks,
> I will set that up and see how this handles the situation ...
>
> Terry
>
I have just set up a SCSI raid array and tried unplugging a drive.
All works as expected here, ie there are error messages from the raid
system and an email to root and the system continues running fine.
So it looks like a bug in the SATA driver ....
Terry
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