[colug-432] md (linux drive mirroring)

Wed Aug 21 18:13:02 EDT 2019

Just for you I pulled a powered up drive out of the USB dock and risked
my data.

I got emailed instantly.

This is from /var/log/kern.log

Aug 21 17:41:02 mach1 kernel: [255336.724544] sd 6:0:0:0: [sde]
Synchronizing SCSI cache
Aug 21 17:41:02 mach1 kernel: [255336.725244] md: super_written gets
error=10
Aug 21 17:41:02 mach1 kernel: [255336.725246] md/raid10:md125: Disk
failure on sde1, disabling device.
Aug 21 17:41:02 mach1 kernel: [255336.725246] md/raid10:md125: Operation
continuing on 3 devices.
Aug 21 17:41:02 mach1 kernel: [255336.725332] md: super_written gets
error=10
Aug 21 17:41:02 mach1 kernel: [255336.725333] md/raid10:md124: Disk
failure on sde2, disabling device.
Aug 21 17:41:02 mach1 kernel: [255336.725333] md/raid10:md124: Operation
continuing on 3 devices.
Aug 21 17:41:02 mach1 kernel: [255336.812856] sd 6:0:0:1: [sdf] tag#25
FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
Aug 21 17:41:02 mach1 kernel: [255336.812858] sd 6:0:0:1: [sdf] tag#25
CDB: Synchronize Cache(10) 35 00 00 00 00 00 00 00 00 00
Aug 21 17:41:02 mach1 kernel: [255336.812875] print_req_error: I/O
error, dev sdf, sector 2064 flags 20801
Aug 21 17:41:02 mach1 kernel: [255336.812878] md: super_written gets
error=10
Aug 21 17:41:02 mach1 kernel: [255336.812880] md/raid10:md125: Disk
failure on sdf1, disabling device.
Aug 21 17:41:02 mach1 kernel: [255336.812880] md/raid10:md125: Operation
continuing on 2 devices.
Aug 21 17:41:02 mach1 kernel: [255336.912850] sd 6:0:0:1: [sdf] tag#27
FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
Aug 21 17:41:02 mach1 kernel: [255336.912852] sd 6:0:0:1: [sdf] tag#27
CDB: Synchronize Cache(10) 35 00 00 00 00 00 00 00 00 00
Aug 21 17:41:02 mach1 kernel: [255336.912855] print_req_error: I/O
error, dev sdf, sector 1953515536 flags 20801
Aug 21 17:41:02 mach1 kernel: [255336.912857] md: super_written gets
error=10
Aug 21 17:41:02 mach1 kernel: [255336.912859] md/raid10:md124: Disk
failure on sdf2, disabling device.
Aug 21 17:41:02 mach1 kernel: [255336.912859] md/raid10:md124: Operation
continuing on 2 devices.

This is from syslog

Aug 21 17:41:02 mach1 kernel: [255336.720913] usb 2-7: USB disconnect,
device number 14
Aug 21 17:41:02 mach1 kernel: [255336.724544] sd 6:0:0:0: [sde]
Synchronizing SCSI cache
Aug 21 17:41:02 mach1 kernel: [255336.725244] md: super_written gets
error=10
Aug 21 17:41:02 mach1 kernel: [255336.725246] md/raid10:md125: Disk
failure on sde1, disabling device.
Aug 21 17:41:02 mach1 kernel: [255336.725246] md/raid10:md125: Operation
continuing on 3 devices.
Aug 21 17:41:02 mach1 kernel: [255336.725332] md: super_written gets
error=10
Aug 21 17:41:02 mach1 kernel: [255336.725333] md/raid10:md124: Disk
failure on sde2, disabling device.
Aug 21 17:41:02 mach1 kernel: [255336.725333] md/raid10:md124: Operation
continuing on 3 devices.
Aug 21 17:41:02 mach1 kernel: [255336.812856] sd 6:0:0:1: [sdf] tag#25
FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
Aug 21 17:41:02 mach1 kernel: [255336.812858] sd 6:0:0:1: [sdf] tag#25
CDB: Synchronize Cache(10) 35 00 00 00 00 00 00 00 00 00
Aug 21 17:41:02 mach1 kernel: [255336.812875] print_req_error: I/O
error, dev sdf, sector 2064 flags 20801
Aug 21 17:41:02 mach1 kernel: [255336.812878] md: super_written gets
error=10
Aug 21 17:41:02 mach1 kernel: [255336.812880] md/raid10:md125: Disk
failure on sdf1, disabling device.
Aug 21 17:41:02 mach1 kernel: [255336.812880] md/raid10:md125: Operation
continuing on 2 devices.
Aug 21 17:41:02 mach1 kernel: [255336.912850] sd 6:0:0:1: [sdf] tag#27
FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
Aug 21 17:41:02 mach1 kernel: [255336.912852] sd 6:0:0:1: [sdf] tag#27
CDB: Synchronize Cache(10) 35 00 00 00 00 00 00 00 00 00
Aug 21 17:41:02 mach1 kernel: [255336.912855] print_req_error: I/O
error, dev sdf, sector 1953515536 flags 20801
Aug 21 17:41:02 mach1 kernel: [255336.912857] md: super_written gets
error=10
Aug 21 17:41:02 mach1 kernel: [255336.912859] md/raid10:md124: Disk
failure on sdf2, disabling device.
Aug 21 17:41:02 mach1 kernel: [255336.912859] md/raid10:md124: Operation
continuing on 2 devices.

Before failure:

$ cat /proc/mdstat
Personalities : [raid0] [linear] [multipath] [raid1] [raid6] [raid5]
[raid4] [raid10]
md124 : active raid10 sdf2[5] sde2[4] sdc2[6] sdd2[7]
       1953251328 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
       bitmap: 0/15 pages [0KB], 65536KB chunk

md125 : active raid10 sdf1[3] sde1[1] sdd1[5] sdc1[4]
       1953251328 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
       bitmap: 0/15 pages [0KB], 65536KB chunk

unused devices: <none>

After failure

$ cat /proc/mdstat
Personalities : [raid0] [linear] [multipath] [raid1] [raid6] [raid5]
[raid4] [raid10]
md124 : active (auto-read-only) raid10 sdc2[6] sdd2[7]
       1953251328 blocks super 1.2 512K chunks 2 near-copies [4/2] [U_U_]
       bitmap: 0/15 pages [0KB], 65536KB chunk

md125 : active (auto-read-only) raid10 sdd1[5] sdc1[4]
       1953251328 blocks super 1.2 512K chunks 2 near-copies [4/2] [U_U_]
       bitmap: 0/15 pages [0KB], 65536KB chunk

unused devices: <none>

On 8/21/19 4:25 PM, Jeff Frontz wrote:
>
> Thanks, Judd -- when the raid failed, were there any syslog/journald
> messages indicating such?
>
>
> On Wed, Aug 21, 2019 at 2:41 PM Judd Montgomery <judd at engineer.com
> <mailto:judd at engineer.com>> wrote:
>
>      I setup md with raid-0, 5 and 10 (tried them all, just playing)
>     with 4 drives.  It would occasionally get corrupted.  I tracked it
>     down to when the 2 docks were turned on in a certain order the
>     kernel would bounce one of them and cause the raid to fail.
>
>
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> colug-432 at colug.net
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