Hi everyone,
as some of you already know I run a non-typical configuration that involves external USB drives assembled as raid1 array. I'm still smoothing out the edges of my setup because of all the challenges associated with not so perfect pm-utils/combination of software and hardware I have.
Anyway, I've been successfully resuming from sleep for a while now but this morning something new happened, namely this:
% cat /proc/mdstat
Personalities : [raid1]
md0 : inactive sdc1[1](S)
1953276928 blocks super 1.2
unused devices: <none>
which made me realize I have no clue what this message mean and what inactive, [1] and (S) mean in "md0 : inactive sdc1[1](S)".
So, I was wondering if somebody could possibly explain how to read this particular instance of mdstat output, and if there is chance there is a documentation somewhere out there that will let me do this myself?
If you're curious (like myself lol) this is what I observed had happened in dmesg/kernel log prior to cat /proc/mdstat
Nov 15 08:25:52 localhost kernel: [29863.901108] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.901115] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.901328] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.901335] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.904392] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.904400] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.905078] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.905086] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.905690] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.905697] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:52 localhost kernel: [29863.918128] md: bind<sdc1>
Nov 15 08:25:58 localhost kernel: [29869.976304] scsi_verify_blk_ioctl: 30 callbacks suppressed
Nov 15 08:25:58 localhost kernel: [29869.976309] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:25:58 localhost kernel: [29869.976314] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:25:58 localhost kernel: [29869.976323] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:58 localhost kernel: [29869.976325] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:59 localhost kernel: [29870.115516] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:25:59 localhost kernel: [29870.115528] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:25:59 localhost kernel: [29870.115543] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:25:59 localhost kernel: [29870.115549] mdadm: sending ioctl 1261 to a partition!
So at this point the system resumed from sleep, and I ran cat /proc/mdstat. Realized that something went wrong and I did not know what to do, so I disconnected the drives, plugged them back in:
Nov 15 08:28:34 localhost kernel: [30025.749558] usb 1-1: USB disconnect, device number 7
Nov 15 08:28:37 localhost kernel: [30028.112008] usb 1-2: USB disconnect, device number 5
Nov 15 08:28:57 localhost kernel: [30048.990409] usb 1-2: new high-speed USB device number 8 using ehci_hcd
Nov 15 08:28:58 localhost kernel: [30049.117229] scsi11 : usb-storage 1-2:1.0
Nov 15 08:28:59 localhost kernel: [30050.121248] scsi 11:0:0:0: Direct-Access WD Elements 1048 1022 PQ: 0 ANSI: 6
Nov 15 08:29:00 localhost kernel: [30050.126571] sd 11:0:0:0: [sdb] Spinning up disk....
Nov 15 08:29:00 localhost kernel: [30051.187081] usb 1-1: new high-speed USB device number 9 using ehci_hcd
Nov 15 08:29:00 localhost kernel: [30051.312832] scsi12 : usb-storage 1-1:1.0
Nov 15 08:29:01 localhost kernel: [30052.133739] .
Nov 15 08:29:01 localhost kernel: [30052.314419] scsi 12:0:0:0: Direct-Access WD Elements 1048 1022 PQ: 0 ANSI: 6
Nov 15 08:29:04 localhost kernel: [30052.320765] sd 12:0:0:0: [sde] Spinning up disk........ready
Nov 15 08:29:04 localhost kernel: [30055.144571] sd 11:0:0:0: [sdb] 3907024896 512-byte logical blocks: (2.00 TB/1.81 TiB)
Nov 15 08:29:04 localhost kernel: [30055.144581] sd 11:0:0:0: [sdb] 4096-byte physical blocks
Nov 15 08:29:04 localhost kernel: [30055.145433] sd 11:0:0:0: [sdb] Write Protect is off
Nov 15 08:29:04 localhost kernel: [30055.145442] sd 11:0:0:0: [sdb] Mode Sense: 47 00 10 08
Nov 15 08:29:04 localhost kernel: [30055.146305] sd 11:0:0:0: [sdb] No Caching mode page present
Nov 15 08:29:04 localhost kernel: [30055.146314] sd 11:0:0:0: [sdb] Assuming drive cache: write through
Nov 15 08:29:04 localhost kernel: [30055.149807] sd 11:0:0:0: [sdb] No Caching mode page present
Nov 15 08:29:04 localhost kernel: [30055.149816] sd 11:0:0:0: [sdb] Assuming drive cache: write through
Nov 15 08:29:04 localhost kernel: [30055.163711] sdb: sdb1
Nov 15 08:29:04 localhost kernel: [30055.169937] sd 11:0:0:0: [sdb] No Caching mode page present
Nov 15 08:29:04 localhost kernel: [30055.169948] sd 11:0:0:0: [sdb] Assuming drive cache: write through
Nov 15 08:29:04 localhost kernel: [30055.169957] sd 11:0:0:0: [sdb] Attached SCSI disk
Nov 15 08:29:04 localhost kernel: [30055.330370] .
Nov 15 08:29:04 localhost kernel: [30055.345968] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:29:04 localhost kernel: [30055.345978] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:29:04 localhost kernel: [30055.346186] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:29:04 localhost kernel: [30055.347627] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:29:04 localhost kernel: [30055.348234] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:29:04 localhost kernel: [30055.348242] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:29:04 localhost kernel: [30055.348838] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:29:04 localhost kernel: [30055.348845] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:29:04 localhost kernel: [30055.360590] md: bind<sdb1>
Nov 15 08:29:06 localhost kernel: [30056.333730] ..ready
Nov 15 08:29:06 localhost kernel: [30057.337894] sd 12:0:0:0: [sde] 3907024896 512-byte logical blocks: (2.00 TB/1.81 TiB)
Nov 15 08:29:06 localhost kernel: [30057.337904] sd 12:0:0:0: [sde] 4096-byte physical blocks
Nov 15 08:29:06 localhost kernel: [30057.338753] sd 12:0:0:0: [sde] Write Protect is off
Nov 15 08:29:06 localhost kernel: [30057.338762] sd 12:0:0:0: [sde] Mode Sense: 47 00 10 08
Nov 15 08:29:06 localhost kernel: [30057.339502] sd 12:0:0:0: [sde] No Caching mode page present
Nov 15 08:29:06 localhost kernel: [30057.339511] sd 12:0:0:0: [sde] Assuming drive cache: write through
Nov 15 08:29:06 localhost kernel: [30057.342516] sd 12:0:0:0: [sde] No Caching mode page present
Nov 15 08:29:06 localhost kernel: [30057.342525] sd 12:0:0:0: [sde] Assuming drive cache: write through
Nov 15 08:29:06 localhost kernel: [30057.354130] sde: sde1
Nov 15 08:29:06 localhost kernel: [30057.359369] sd 12:0:0:0: [sde] No Caching mode page present
Nov 15 08:29:06 localhost kernel: [30057.359381] sd 12:0:0:0: [sde] Assuming drive cache: write through
Nov 15 08:29:06 localhost kernel: [30057.359369] sd 12:0:0:0: [sde] No Caching mode page present
Nov 15 08:29:06 localhost kernel: [30057.359381] sd 12:0:0:0: [sde] Assuming drive cache: write through
Nov 15 08:29:06 localhost kernel: [30057.359390] sd 12:0:0:0: [sde] Attached SCSI disk
Nov 15 08:29:06 localhost kernel: [30057.565248] md: export_rdev(sde1)
Nov 15 08:29:06 localhost kernel: [30057.566615] md: export_rdev(sde1)
Nov 15 08:30:57 localhost kernel: [30168.336551] md: md0 stopped.
Nov 15 08:30:57 localhost kernel: [30168.336562] md: unbind<sdb1>
Nov 15 08:30:57 localhost kernel: [30168.336669] md: export_rdev(sdb1)
Nov 15 08:30:57 localhost kernel: [30168.336689] md: unbind<sdc1>
Nov 15 08:30:57 localhost kernel: [30168.340361] md: export_rdev(sdc1)
The array did not assemble automatically this time either, and mdstat showed the same state. So, this time I decided to run
% mdadm --stop --scan
mdadm: stopped /dev/md0
% mdadm --assemble --scan
mdadm: /dev/md0 has been started with 2 drives.
and it assembled just fine
% cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sdb1[2] sde1[1]
1953276736 blocks super 1.2 [2/2] [UU]
bitmap: 0/15 pages [0KB], 65536KB chunk
unused devices: <none>
Here's the corresponding kernel log
Nov 15 08:31:06 localhost kernel: [30177.083700] scsi_verify_blk_ioctl: 48 callbacks suppressed
Nov 15 08:31:06 localhost kernel: [30177.083709] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.083717] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.083737] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.083743] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.086150] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.086158] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.086168] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.086174] mdadm: sending ioctl 1261 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.087982] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.087992] mdadm: sending ioctl 800c0910 to a partition!
Nov 15 08:31:06 localhost kernel: [30177.923752] md: md0 stopped.
Nov 15 08:31:07 localhost kernel: [30177.936426] md: bind<sde1>
Nov 15 08:31:07 localhost kernel: [30177.937166] md: bind<sdb1>
Nov 15 08:31:07 localhost kernel: [30178.382401] md/raid1:md0: active with 2 out of 2 mirrors
Nov 15 08:31:07 localhost kernel: [30178.463060] created bitmap (15 pages) for device md0
Nov 15 08:31:07 localhost kernel: [30178.470165] md0: bitmap initialized from disk: read 1/1 pages, set 0 of 29805 bits
Nov 15 08:31:07 localhost kernel: [30178.959261] md0: detected capacity change from 0 to 2000155377664
Nov 15 08:31:08 localhost kernel: [30179.019629] md0: unknown partition table
So, I think these messages are the gist of it all:
Nov 15 08:29:06 localhost kernel: [30057.565248] md: export_rdev(sde1)
Nov 15 08:29:06 localhost kernel: [30057.566615] md: export_rdev(sde1)
Nov 15 08:30:57 localhost kernel: [30168.336551] md: md0 stopped.
Nov 15 08:30:57 localhost kernel: [30168.336562] md: unbind<sdb1>
Nov 15 08:30:57 localhost kernel: [30168.336669] md: export_rdev(sdb1)
Nov 15 08:30:57 localhost kernel: [30168.336689] md: unbind<sdc1>
Nov 15 08:30:57 localhost kernel: [30168.340361] md: export_rdev(sdc1)
What do they mean? What is export of rdev? What kind of device is considered to be an rdev? What does this sequence of message tell me in human language? :)
I know, some of you feel very strongly about using USB for this sort of thing, but so far I've been enjoying my ride. Both in terms of stability and how it is pushing me to learn more about mdadm and RAID technology in general. Yes, the stability is far from enterprise grade systems, but I'm an enthusiast like perhaps many of you here and this has proven to be a very good training wheels. Besides, even though it is a bumpy ride, it is kinda fun, you know? ;D
Ivan--
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