<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Jun 17, 2017 at 1:25 AM, Markus Stockhausen <span dir="ltr"><<a href="mailto:stockhausen@collogia.de" target="_blank">stockhausen@collogia.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div>Hi, </div>
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<div>we just set up a new 4.1.2 OVirt cluster. It is a quite normal</div>
<div>HDD/XFS/NFS stack that worked quit well with 4.0 in the past. </div>
<div>Inside the VMs we use XFS too.</div>
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<div>To our surprise we observe abysmal high IO during mkfs.xfs </div>
<div>and fstrim inside the VM. A simple example:</div>
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<div>Step 1: Create 100G Thin disk</div>
<div>Result 1: Disk occupies ~10M on storage</div>
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<div>Step 2: Format disk inside VM with mkfs.xfs</div>
<div>Result 2: Disk occupies 100G on storage</div>
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<div>Changing the discard flag on the disk does not have any effect.</div></div></div></div></div></div></div></div></div></blockquote><div><br></div><div>Are you sure it's discarding, at all?</div><div>1. NFS: only NFSv4.2 supports discard. Is that the case in your setup?</div><div>2. What's the value of /sys/block/<disk>/queue/discard_granularity ?</div><div>3. Can you share the mkfs.xfs command line?</div><div>4. Are you sure it's not a raw-sparse image?</div><div>Y.</div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="direction:ltr;font-family:Arial;color:rgb(0,0,0);font-size:10pt"><div style="font-family:Tahoma;font-size:13px"><div style="font-family:Tahoma;font-size:13px"><div style="font-family:Tahoma;font-size:13px"><div style="font-family:Tahoma;font-size:13px"><div style="font-family:Tahoma;font-size:13px"><div>
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<div>Am I missing something?</div>
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<div>Best regards.</div><span class="gmail-HOEnZb"><font color="#888888">
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<div>Markus</div>
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