On Sat, Jun 17, 2017 at 1:25 AM, Markus Stockhausen <stockhau...@collogia.de > wrote:
> Hi, > > we just set up a new 4.1.2 OVirt cluster. It is a quite normal > HDD/XFS/NFS stack that worked quit well with 4.0 in the past. > Inside the VMs we use XFS too. > > To our surprise we observe abysmal high IO during mkfs.xfs > and fstrim inside the VM. A simple example: > > Step 1: Create 100G Thin disk > Result 1: Disk occupies ~10M on storage > > Step 2: Format disk inside VM with mkfs.xfs > Result 2: Disk occupies 100G on storage > > Changing the discard flag on the disk does not have any effect. > Are you sure it's discarding, at all? 1. NFS: only NFSv4.2 supports discard. Is that the case in your setup? 2. What's the value of /sys/block/<disk>/queue/discard_granularity ? 3. Can you share the mkfs.xfs command line? 4. Are you sure it's not a raw-sparse image? Y. > Am I missing something? > > Best regards. > > Markus > > _______________________________________________ > Users mailing list > Users@ovirt.org > http://lists.ovirt.org/mailman/listinfo/users > >
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