VDI_IO_ERROR(Device I/O errors) when you run scheduled backup

shorian

Forgot to say - the duplicate referred to in the error is the “[Importing...BackupProcessName-timestamp] halted VM that the backup process itself creates - ie the remnants that I spoke of at the outset that needed to be removed that don’t show in the GUI but can be seen via CLI using

xe vm-list power-state=halted

shorian

Have just updated the hosts with the swathe of patches that came out this morning, and tested with a fresh build from master as of today.

Unfortunately still getting these VDI_IO_ERROR errors when running CR, be it from a trial XOA install or from the latest build from master (rebuilt this morning); nothing particularly helpful jumping out of the logs:

2021-01-23T15_43_13.502Z - backup NG.log.txt

Question to the community - are other people seeing the same VDI_IO_ERROR error occasionally, or is this a unique case? Even if you can't provide access to your logs for privacy reasons, it would be interesting to know if others are seeing it. Of course, that relies upon others seeing this message....

Thanks!

olivierlambert

Check the usual logs (SMlog and dmesg) to see if we can spot the root cause.

shorian

@olivierlambert Nothing jumps out from dmesg and nothing useful in SMlog when running the CR, however do get the following exceptions in SMlog upon boot (same error for each disk array):

 SMGC: [24044] *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
 SMGC: [24044]          ***********************
 SMGC: [24044]          *  E X C E P T I O N  *
 SMGC: [24044]          ***********************
 SMGC: [24044] gc: EXCEPTION <class 'util.SMException'>, SR 7e772759-f44e-af14-eb45-e839cc67689c not attached on this host
 SMGC: [24044]   File "/opt/xensource/sm/cleanup.py", line 3354, in gc
 SMGC: [24044]     _gc(None, srUuid, dryRun)
 SMGC: [24044]   File "/opt/xensource/sm/cleanup.py", line 3233, in _gc
 SMGC: [24044]     sr = SR.getInstance(srUuid, session)
 SMGC: [24044]   File "/opt/xensource/sm/cleanup.py", line 1552, in getInstance
 SMGC: [24044]     return FileSR(uuid, xapi, createLock, force)
 SMGC: [24044]   File "/opt/xensource/sm/cleanup.py", line 2330, in __init__
 SMGC: [24044]     SR.__init__(self, uuid, xapi, createLock, force)
 SMGC: [24044]   File "/opt/xensource/sm/cleanup.py", line 1582, in __init__
 SMGC: [24044]     raise util.SMException("SR %s not attached on this host" % uuid)
 SMGC: [24044]
 SMGC: [24044] *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
 SMGC: [24044] * * * * * SR 7e772759-f44e-af14-eb45-e839cc67689c: ERROR
 SMGC: [24044]
 SM: [24066] lock: opening lock file /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/sr
 SM: [24066] sr_update {'sr_uuid': '7e772759-f44e-af14-eb45-e839cc67689c', 'subtask_of': 'DummyRef:|ed453e0f-248d-403f-9499-ee7255fdf429|SR.stat', 'args': [], 'host_ref': 'OpaqueRef:c1b3f3e8-579b-4b35-9bb6-dcad830583c3', 'session_ref': 'OpaqueRef:dafc19b5-65af-4501-a151-1999d8e7f550', 'device_config': {'device': '/dev/disk/by-id/scsi-2ad3a730200d00000-part1', 'SRmaster': 'true'}, 'command': 'sr_update', 'sr_ref': 'OpaqueRef:bfd47d28-1be1-4dd6-8a7b-2c0a986b8d47', 'local_cache_sr': '34bd3a97-3562-75af-a24e-a266caf368e3'}
 SM: [24088] lock: opening lock file /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/sr
 SM: [24088] lock: acquired /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/sr
 SM: [24088] sr_scan {'sr_uuid': '7e772759-f44e-af14-eb45-e839cc67689c', 'subtask_of': 'DummyRef:|017c9f00-7289-4983-a942-f91c830fed33|SR.scan', 'args': [], 'host_ref': 'OpaqueRef:c1b3f3e8-579b-4b35-9bb6-dcad830583c3', 'session_ref': 'OpaqueRef:a907696c-b7cf-4ac8-b772-b22833073585', 'device_config': {'device': '/dev/disk/by-id/scsi-2ad3a730200d00000-part1', 'SRmaster': 'true'}, 'command': 'sr_scan', 'sr_ref': 'OpaqueRef:bfd47d28-1be1-4dd6-8a7b-2c0a986b8d47', 'local_cache_sr': '34bd3a97-3562-75af-a24e-a266caf368e3'}
 SM: [24088] ['/usr/bin/vhd-util', 'scan', '-f', '-m', '/var/run/sr-mount/7e772759-f44e-af14-eb45-e839cc67689c/*.vhd']
 SM: [24088]   pread SUCCESS
 SM: [24088] ['ls', '/var/run/sr-mount/7e772759-f44e-af14-eb45-e839cc67689c', '-1', '--color=never']
 SM: [24088]   pread SUCCESS
 SM: [24088] lock: opening lock file /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/running
 SM: [24088] lock: tried lock /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/running, acquired: True (exists: True)
 SM: [24088] lock: released /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/running
 SM: [24088] Kicking GC
 SMGC: [24088] === SR 7e772759-f44e-af14-eb45-e839cc67689c: gc ===
 SMGC: [24104] Will finish as PID [24105]
 SM: [24105] lock: opening lock file /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/running
 SMGC: [24088] New PID [24104]
 SM: [24105] lock: opening lock file /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/gc_active
 SM: [24088] lock: released /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/sr
 SM: [24105] lock: opening lock file /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/sr
 SMGC: [24105] Found 0 cache files
 SM: [24105] lock: tried lock /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/gc_active, acquired: True (exists: True)
 SM: [24105] lock: tried lock /var/lock/sm/7e772759-f44e-af14-eb45-e839cc67689c/sr, acquired: True (exists: True)
 SM: [24105] ['/usr/bin/vhd-util', 'scan', '-f', '-m', '/var/run/sr-mount/7e772759-f44e-af14-eb45-e839cc67689c/*.vhd']
 SM: [24105]   pread SUCCESS

Subsequent to above, found that get identical error when reattaching SR (after detaching it).

xapi-explore-sr does not show anything interesting

Thanks chap; v kind of you

olivierlambert

@shorian said in VDI_IO_ERROR(Device I/O errors) when you run scheduled backup:

SR 7e772759-f44e-af14-eb45-e839cc67689c not attached on this host

Weird. Is it a shared SR? If it's the case, the master node need to have access to the SR (because coalesce mechanism works on the master).

shorian

@olivierlambert Nope, not shared. Standalone box with two local disk arrays, both reporting the same error on boot / reattaching, yet seem performant for normal operations. We only get the exception error in SMlog when booting and frequent (but not always) VDI_IO_ERRORs when taking backups. VMs themselves seem to be fine. Quite strange

Both SRs are ext4 in RAID1, one array of 2xSSD and one of 2xSATA.

Should I try reinstalling the host?

olivierlambert

That's weird. Can you double check there's no "ghost" host that have been there bore? Eg with xe host-list.

Also a xe sr-param-list uuid=7e772759-f44e-af14-eb45-e839cc67689c to see if we can spot anything.

shorian

@olivierlambert Afraid nothing interesting:

# xe host-list
uuid ( RO)                : 3d60f1d4-595e-4428-9c24-6409db9593bc
          name-label ( RW): xen11
    name-description ( RW): ABC

# xe sr-param-list uuid=7e772759-f44e-af14-eb45-e839cc67689c

uuid ( RO)                    : 7e772759-f44e-af14-eb45-e839cc67689c
              name-label ( RW): Xen11 SSD
        name-description ( RW): Xen11 SSD
                    host ( RO): xen11
      allowed-operations (SRO): VDI.enable_cbt; VDI.list_changed_blocks; unplug; plug; PBD.create; VDI.disable_cbt; update; PBD.destroy; VDI.resize; VDI.clone; VDI.data_destroy; scan; VDI.snapshot; VDI.mirror; VDI.create; VDI.destroy; VDI.set_on_boot
      current-operations (SRO):
                    VDIs (SRO):
                    PBDs (SRO): 9e967e89-7263-40b5-5706-cd2d449b7192
      virtual-allocation ( RO): 0
    physical-utilisation ( RO): 75665408
           physical-size ( RO): 491294261248
                    type ( RO): ext
            content-type ( RO): user
                  shared ( RW): false
           introduced-by ( RO): <not in database>
             is-tools-sr ( RO): false
            other-config (MRW):
               sm-config (MRO): devserial: scsi-2ad3a730200d00000
                   blobs ( RO):
     local-cache-enabled ( RO): false
                    tags (SRW):
               clustered ( RO): false

olivierlambert

What about xe pbd-param-list uuid=9e967e89-7263-40b5-5706-cd2d449b7192?

shorian

# xe pbd-param-list uuid=9e967e89-7263-40b5-5706-cd2d449b7192
uuid ( RO)                  : 9e967e89-7263-40b5-5706-cd2d449b7192
     host ( RO) [DEPRECATED]: 3d60f1d4-595e-4428-9c24-6409db9593bc
             host-uuid ( RO): 3d60f1d4-595e-4428-9c24-6409db9593bc
       host-name-label ( RO): xen11
               sr-uuid ( RO): 7e772759-f44e-af14-eb45-e839cc67689c
         sr-name-label ( RO): Xen11 SSD
         device-config (MRO): device: /dev/disk/by-id/scsi-2ad3a730200d00000-part1
    currently-attached ( RO): true
          other-config (MRW): storage_driver_domain: OpaqueRef:ce759085-6e0d-4484-9f8a-abf75b822f75

olivierlambert

Indeed, nothing special here.

shorian

I'll try a fresh install over the next couple of days and see if it reoccurs. Looking at the other boxes, I have the same error on one of the other hosts, but it's not across all of them despite identical installs and hardware.

Thanks for your efforts and help, shame there wasn't an easy answer but let's see if it reoccurs after a completely fresh install.

olivierlambert

Please keep us posted

shorian

Have just run a clean install - identical error in SMlog

Following was the last message in dmesg which seems counter to the SMlog error

EXT4-fs (dm-0): mounted filesystem with ordered data mode. Opts: (null)

Can send full SMlog and anything else you can think of - but it's either a hardware error (in which case why identical error accross two hosts?) or an incorrect setting in the install process. I'm at a loss

shorian

Have tried reformatting disks after changing the boot record - previously was GPT with ext4, have tried using MBR instead but no difference, even after another fresh install.

I'm going through a comparison with another machine that is identical kit but doesn't have those errors, but can't see any differences whatsoever

olivierlambert

Do you have a 4K sector disk?

shorian

The (large) SATA drives are, but the SSDs are not; problem is reported for both.

# parted /dev/sdb print

Model: AVAGO MR9363-4i (scsi)
Disk /dev/sdb: 6001GB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt
Disk Flags:

Number  Start   End     Size    File system     Name  Flags
 5      1049kB  4296MB  4295MB  ext3
 2      4296MB  23.6GB  19.3GB
 1      23.6GB  43.0GB  19.3GB  ext3
 4      43.0GB  43.5GB  537MB   fat16                 boot
 6      43.5GB  44.6GB  1074MB  linux-swap(v1)
 3      44.6GB  6001GB  5956GB                        lvm

# parted /dev/sda print

Model: AVAGO MR9363-4i (scsi)
Disk /dev/sda: 500GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number  Start   End    Size   File system  Name              Flags
 1      1049kB  500GB  500GB               Linux filesystem

Also contrary to my thoughts above - the other machines do have the same errors in SMlog, only they've not been rebooted for many moons so it was in the archived off logs rather than current. So the problem is consistent across the entire estate.

olivierlambert

Before refocusing on the original issue, the SMlog error you have on reboot/boot, is it preventing you to use the SR?

shorian

No, everything seems to work just fine, except for the failure errors when running CR backups, and the messages in the logs when booting / attaching. The VMs themselves are performant, can be migrated on and off the host, and are handling production loads. If it wasn't for the CR errors, I would never have noticed them.

Meanwhile I've dug through the old Xen bug lists and found some similar SR issues but they seem to result in failure to mount but nothing that matches our specific situation.

olivierlambert

Hmm that's weird. I don't know what's causing this. Can you try with a local LVM SR and see if you have the exact same issue? (trying to see if it's related to the storage driver)