On 2016-04-21 02:23, Satoru Takeuchi wrote:
On 2016/04/20 14:17, Matthias Bodenbinder wrote:
Am 18.04.2016 um 09:22 schrieb Qu Wenruo:
BTW, it would be better to post the dmesg for better debug.
So here we. I did the same test again. Here is a full log of what i
did. It seems to be mean like a bug in btrfs.
Sequenz of events:
1. mount the raid1 (2 disc with different size)
2. unplug the biggest drive (hotplug)
3. try to copy something to the degraded raid1
4. plugin the device again (hotplug)
This scenario does not work. The disc array is NOT redundant! I can
not work with it while a drive is missing and I can not reattach the
device so that everything works again.
The btrfs module crashes during the test.
I am using LMDE2 with backports:
btrfs-tools 4.4-1~bpo8+1
linux-image-4.4.0-0.bpo.1-amd64
Matthias
rakete - root - /root
1# mount /mnt/raid1/
Journal:
Apr 20 07:01:16 rakete kernel: BTRFS info (device sdi): enabling auto
defrag
Apr 20 07:01:16 rakete kernel: BTRFS info (device sdi): disk space
caching is enabled
Apr 20 07:01:16 rakete kernel: BTRFS: has skinny extents
rakete - root - /mnt/raid1
3# ll
insgesamt 0
drwxrwxr-x 1 root root 36 Nov 14 2014 AfterShot2(64-bit)
drwxrwxr-x 1 root root 5082 Apr 17 09:06 etc
drwxr-xr-x 1 root root 108 Mär 24 07:31 var
4# btrfs fi show
Label: none uuid: 16d5891f-5d52-4b29-8591-588ddf11e73d
Total devices 3 FS bytes used 1.60GiB
devid 1 size 698.64GiB used 3.03GiB path /dev/sdg
devid 2 size 465.76GiB used 3.03GiB path /dev/sdh
devid 3 size 232.88GiB used 0.00B path /dev/sdi
####
unplug device sdg:
Apr 20 07:03:05 rakete kernel: Buffer I/O error on dev sdf1, logical
block 243826688, lost sync page write
Apr 20 07:03:05 rakete kernel: JBD2: Error -5 detected when updating
journal superblock for sdf1-8.
Apr 20 07:03:05 rakete kernel: Aborting journal on device sdf1-8.
Apr 20 07:03:05 rakete kernel: Buffer I/O error on dev sdf1, logical
block 243826688, lost sync page write
Apr 20 07:03:05 rakete kernel: JBD2: Error -5 detected when updating
journal superblock for sdf1-8.
Apr 20 07:03:05 rakete umount[16405]: umount: /mnt/raid1: target is busy
Apr 20 07:03:05 rakete umount[16405]: (In some cases useful info about
processes that
Apr 20 07:03:05 rakete umount[16405]: use the device is found by
lsof(8) or fuser(1).)
Apr 20 07:03:05 rakete systemd[1]: mnt-raid1.mount mount process
exited, code=exited status=32
Apr 20 07:03:05 rakete systemd[1]: Failed unmounting /mnt/raid1.
Apr 20 07:03:24 rakete kernel: usb 3-1: new SuperSpeed USB device
number 3 using xhci_hcd
Apr 20 07:03:24 rakete kernel: usb 3-1: New USB device found,
idVendor=152d, idProduct=0567
Apr 20 07:03:24 rakete kernel: usb 3-1: New USB device strings:
Mfr=10, Product=11, SerialNumber=5
Apr 20 07:03:24 rakete kernel: usb 3-1: Product: USB to ATA/ATAPI Bridge
Apr 20 07:03:24 rakete kernel: usb 3-1: Manufacturer: JMicron
Apr 20 07:03:24 rakete kernel: usb 3-1: SerialNumber: 152D00539000
Apr 20 07:03:24 rakete kernel: usb-storage 3-1:1.0: USB Mass Storage
device detected
Apr 20 07:03:24 rakete kernel: usb-storage 3-1:1.0: Quirks match for
vid 152d pid 0567: 5000000
Apr 20 07:03:24 rakete kernel: scsi host9: usb-storage 3-1:1.0
Apr 20 07:03:24 rakete mtp-probe[16424]: checking bus 3, device 3:
"/sys/devices/pci0000:00/0000:00:1c.5/0000:04:00.0/usb3/3-1"
Apr 20 07:03:24 rakete mtp-probe[16424]: bus: 3, device: 3 was not an
MTP device
Apr 20 07:03:25 rakete kernel: scsi 9:0:0:0: Direct-Access WDC
WD20 02FAEX-007BA0 0125 PQ: 0 ANSI: 6
Apr 20 07:03:25 rakete kernel: scsi 9:0:0:1: Direct-Access WDC
WD50 01AALS-00L3B2 0125 PQ: 0 ANSI: 6
Apr 20 07:03:25 rakete kernel: scsi 9:0:0:2: Direct-Access
SAMSUNG SP2504C 0125 PQ: 0 ANSI: 6
Apr 20 07:03:25 rakete kernel: sd 9:0:0:0: Attached scsi generic sg6
type 0
Apr 20 07:03:25 rakete kernel: sd 9:0:0:1: Attached scsi generic sg7
type 0
Apr 20 07:03:25 rakete kernel: sd 9:0:0:0: [sdf] 3907029168 512-byte
logical blocks: (2.00 TB/1.82 TiB)
Apr 20 07:03:25 rakete kernel: sd 9:0:0:0: [sdf] Write Protect is off
Apr 20 07:03:25 rakete kernel: sd 9:0:0:0: [sdf] Mode Sense: 67 00 10 08
Apr 20 07:03:25 rakete kernel: sd 9:0:0:2: Attached scsi generic sg8
type 0
Apr 20 07:03:25 rakete kernel: sd 9:0:0:1: [sdj] 976773168 512-byte
logical blocks: (500 GB/466 GiB)
Apr 20 07:03:25 rakete kernel: sd 9:0:0:0: [sdf] No Caching mode page
found
Apr 20 07:03:25 rakete kernel: sd 9:0:0:0: [sdf] Assuming drive cache:
write through
Apr 20 07:03:25 rakete kernel: sd 9:0:0:1: [sdj] Write Protect is off
Apr 20 07:03:25 rakete kernel: sd 9:0:0:1: [sdj] Mode Sense: 67 00 10 08
Apr 20 07:03:25 rakete kernel: sd 9:0:0:2: [sdk] 488395055 512-byte
logical blocks: (250 GB/233 GiB)
Apr 20 07:03:25 rakete kernel: sd 9:0:0:1: [sdj] No Caching mode page
found
Apr 20 07:03:25 rakete kernel: sd 9:0:0:1: [sdj] Assuming drive cache:
write through
Apr 20 07:03:25 rakete kernel: sd 9:0:0:2: [sdk] Write Protect is off
Apr 20 07:03:25 rakete kernel: sd 9:0:0:2: [sdk] Mode Sense: 67 00 10 08
Apr 20 07:03:25 rakete kernel: sd 9:0:0:2: [sdk] No Caching mode page
found
Apr 20 07:03:25 rakete kernel: sd 9:0:0:2: [sdk] Assuming drive cache:
write through
Apr 20 07:03:25 rakete kernel: sdf: sdf1
Apr 20 07:03:25 rakete kernel: sd 9:0:0:0: [sdf] Attached SCSI disk
Apr 20 07:03:25 rakete kernel: sd 9:0:0:1: [sdj] Attached SCSI disk
Apr 20 07:03:25 rakete kernel: sd 9:0:0:2: [sdk] Attached SCSI disk
Apr 20 07:03:25 rakete kernel: EXT4-fs (sdf1): recovery complete
Apr 20 07:03:25 rakete kernel: EXT4-fs (sdf1): mounted filesystem with
ordered data mode. Opts: (null)
Apr 20 07:03:25 rakete udisksd[3671]: Error statting /dev/sdg: No such
file or directory
####
5# btrfs fi show
Label: none uuid: 16d5891f-5d52-4b29-8591-588ddf11e73d
Total devices 3 FS bytes used 1.60GiB
devid 2 size 465.76GiB used 3.03GiB path /dev/sdj
devid 3 size 232.88GiB used 0.00B path /dev/sdk
*** Some devices missing
####
Here the names of *online* devices are changed
(/dev/sdh => /dev/sdj, /dev/sdi => /dev/sdk) after just
offlining a device (/dev/sdf). It's odd regardless of
whether Btrfs works fine or not.
Can anyone explain this behavior?
It's a side effect of the reference counting done in the kernel. If
something is holding open references to the block device (for example,
if there's a mounted filesystem on one of it's partitions), then the
kernel has to keep the internal structures relating to that block device
around, even if the device isn't there anymore. This means that when
the disk reappears, the old name is still in use, so the kernel has to
allocate a new one (because it can't safely assume that the disk is the
same one that was there previously). It has some annoying side effects,
but it's still a whole lot better than the system crashing from a NULL
pointer reference.
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