Gilboa Davara wrote:
On Wed, 2006-02-01 at 10:36 +0000, Terry Barnaby wrote:
Gilboa Davara wrote:
On Wed, 2006-02-01 at 09:45 +0000, Terry Barnaby wrote:
Hi,
I have just set up a Raid 5 disk array using 4 SATA disks on Fedora 4.
To test the setup I unplugged the SATA cable from one of the disk drives.
I was expected the system to carry on with messages from the Raid system
indicating that there was a disk drive down.
However the Raid 5 partition became completely inaccessable after un-plugging
the drive. The kernel reported disk errors but there was no error messages
from the Raid system and "mdadm -Q --detail /dev/md2" reported that there
was no problems with the Raid array.
When I rebooted the system (needed a reset) the Raid system reported that
one disk was down and the partition became readable again.
It appears that the default configuration of the Raid 5 system does not
handle a complete drive failier during up-time. I presume it may respond to
disk errors from a disk drive that is connected but once disconnected the
Raid system appears to ignore errors.
Is there a configuration option to allow the Raid system to respond to
a completely broken drive or cable ?
Terry
A. Are you sure your machine/controller hot plug? SATA doesn't support
it by default. (You'll need special drive enclosures and
hot-plug-supporting controller.
B. Can you post your complete machine configuration?
Gilboa
Hi,
Thank you for the response.
A. No, I don't think the SATA controller is a hot-plug-supporting controller.
It is a: "Intel Corporation 82801FB/FW (ICH6/ICH6W) SATA Controller (rev 04)".
B.
Motherboard: AOPEN i915Ga-PLF
CPU: Pentum 4 3GHz
Disks: 4 * SATA WD Caviar 320G
Paritions: Each disk has: 1 - 20G, 2 - 1G (swap), 3 - ~300G
Raid: "/" /dev/md0 Raid1 using /dev/sda1,/dev/sdb1
"/spare" /dev/md1 Raid1 using /dev/sdc1,/dev/sdd1
"/data" /dev/md2 Raid5 using /dev/sda3,/dev/sdb3,/dev/sdc3,/dev/sdd3
Although the SATA controller is not a "hot-plug" controller I assumed that
disconnecting a SATA disk to simulate a cable failier or complete drive failier
would cause the RAID system to react correctly. Certainly I see kernel
error messages from the disk/controller in question and I would have assumed that
the RAID system would react to this ...
Terry
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
