[PVE-User] LVM over ISCSI issue

Yannis Milios yannis.milios at gmail.com
Tue Aug 11 18:19:53 CEST 2020


Just out of curiosity, can you temporarily disable discard support on the
target VM disk to see if that will make a difference?


On Tue, 11 Aug 2020 at 11:52, Amin Vakil via pve-user <
pve-user at lists.proxmox.com> wrote:

>
>
>
> ---------- Forwarded message ----------
> From: Amin Vakil <info at aminvakil.com>
> To: pve-user at lists.proxmox.com
> Cc:
> Bcc:
> Date: Tue, 11 Aug 2020 15:22:02 +0430
> Subject: [PVE-User] LVM over ISCSI issue
> Sorry, I just realized I've send my previous email with wrong subject.
>
> > Looks like you are trying to clone an existing VM stored on the NFS
> server
> > to the iSCSI target. Problem is that both the NFS server and iSCSI target
> > are served by the same machine, so my best guess is that the I/O on the
> > storage server is getting saturated. Have you tried creating a new VM on
> > iSCSI instead ? Can you also try setting bandwidth limits at "Datacenter
> ->
> > Options -> Bandwidth Limits" and then retry cloning operation ?
> >
>
> I cloned to nfs to make sure it's ok, it doesn't make any difference
> when cloning from local or nfs to iscsi. the problem is the same, here
> is the log cloning from local to iscsi: http://ix.io/2tRX
>
> Also sometimes it errors in the middle of cloning process:
> http://ix.io/2tRV
>
> Creating a vm and adding a disk on iscsi to an existing vm is fine.
>
> I have set bandwidth limits and it didn't make any difference.
>
> >>> kernel: blk_update_request: I/O error, dev sdb, sector 1762240503 op
> > 0x9:(WRITE_ZEROES) flags 0x0 phys_seg 0 prio class 0
> >
> > Is this on the storage server or the PVE host ? What does /dev/sdb
> > represent in this case ? if it's a hard drive, it looks like it's having
> > some hw issues ? Better to test with smartctl if that's the case.
>
> The storage server is a qnap NAS, and it's health and smart is
> constantly monitored. Of course faulty hardware can never be ruled out
> completely, but I doubt that would be the case, because qnap smart
> status and hard health is ok and none of the running VMs on iscsi are
> facing any issue.
>
> fdisk -l:
> ...
> Disk /dev/sdb: 3.9 TiB, 4294967296000 bytes, 8388608000 sectors
> Disk model: iSCSI Storage
> ...
>
> iscsiadm -m session -P 2:
> http://ix.io/2tRY (ip address and username have been changed, everything
> else are unchanged)
>
> Although I have cloned to iscsi now, but it succeed after trying many
> times, the error seems to be random.
>
> Also if it helps someone on ##proxmox IRC told me this:
> it basically fails at the sparse scsi command
> WRITE_ZEROES
> that is _usually_ an array issue
>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Amin Vakil via pve-user <pve-user at lists.proxmox.com>
> To: pve-user at lists.proxmox.com
> Cc: Amin Vakil <info at aminvakil.com>
> Bcc:
> Date: Tue, 11 Aug 2020 15:22:02 +0430
> Subject: [PVE-User] LVM over ISCSI issue
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