<div dir="ltr">Hi Nir thanks for the guidance<div><br></div><div>We started to use ovirt a good few years ago now (version 3.2). </div><div><br></div><div>At the time iscsi multipath wasn't supported, so we made our own modifications to vdsm and this worked well with direct lun.</div><div>We decided to go with direct lun in case things didn't work out with OVirt and in that case we would go back to using vanilla kvm / virt-manager.</div><div><br></div><div>At the time I don't believe that you could import iscsi data domains that had already been configured into a different installation, so we replicated each raw VM volume using the SAN to another server room for DR purposes.</div><div>We use Dell Equallogic and there is a documented limitation of 1024 iscsi connections and 256 volume replications. This isn't a problem at the moment, but the more VMs that we have the more conscious I am about us reaching those limits (we have around 300 VMs at the moment and we have a vdsm hook that closes off iscsi connections if a vm is migrated /powered off).</div><div><br></div><div>Moving to storage domains keeps the number of iscsi connections / replicated volumes down and we won't need to make custom changes to vdsm when we upgrade.</div><div>We can then use the SAN to replicate the storage domains to another data centre and bring that online with a different install of OVirt (we will have to use these arrays for at least the next 3 years).</div><div><br></div><div>I didn't realise that each storage domain contained the configuration details/metadata for the VMs.</div><div>This to me is an extra win as we can recover VMs faster than we can now if we have to move them to a different data centre in the event of a disaster.</div><div><br></div><div><br></div><div>Are there any maximum size / vm limits or recommendations for each storage domain ?</div><div>Does Ovirt support moving VM's between different storage domain type e.g. ISCSI to gluster ?</div><div><br></div><div><br></div><div>Many Thanks</div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><i>Gary Lloyd</i><div><span style="color:rgb(136,136,136)">______________________________</span><span style="color:rgb(136,136,136)">__________________</span><br><div><span style="color:rgb(136,136,136)">I.T. Systems:Keele University</span><br style="color:rgb(136,136,136)"><span style="color:rgb(136,136,136)">Finance & IT Directorate</span></div><div><span style="color:rgb(136,136,136)">Keele:Staffs:IC1 Building:ST5 5NB:UK</span><br style="color:rgb(136,136,136)"><a href="tel:%2B44%201782%20733073" value="+441782733073" style="color:rgb(17,85,204)" target="_blank">+44 1782 733063</a><br style="color:rgb(136,136,136)"><span style="color:rgb(136,136,136)">______________________________</span><span style="color:rgb(136,136,136)">__________________</span></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On 15 February 2017 at 18:56, Nir Soffer <span dir="ltr"><<a href="mailto:nsoffer@redhat.com" target="_blank">nsoffer@redhat.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Wed, Feb 15, 2017 at 2:32 PM, Gary Lloyd <<a href="mailto:g.lloyd@keele.ac.uk">g.lloyd@keele.ac.uk</a>> wrote:<br>
> Hi<br>
><br>
> We currently use direct lun for our virtual machines and I would like to<br>
> move away from doing this and move onto storage domains.<br>
><br>
> At the moment we are using an ISCSI SAN and we use on replicas created on<br>
> the SAN for disaster recovery.<br>
><br>
> As a test I thought I would replicate an existing storage domain's volume<br>
> (via the SAN) and try to mount again as a separate storage domain (This is<br>
> with ovirt 4.06 (cluster mode 3.6))<br>
<br>
Why do want to replicate a storage domain and connect to it?<br>
<br>
> I can log into the iscsi disk but then nothing gets listed under Storage<br>
> Name / Storage ID (VG Name)<br>
><br>
><br>
> Should this be possible or will it not work due the the uids being identical<br>
> ?<br>
<br>
Connecting 2 storage domains with same uid will not work. You can use either<br>
the old or the new, but not both at the same time.<br>
<br>
Can you explain how replicating the storage domain volume is related to<br>
moving from direct luns to storage domains?<br>
<br>
If you want to move from direct lun to storage domain, you need to create<br>
a new disk on the storage domain, and copy the direct lun data to the new<br>
disk.<br>
<br>
We don't support this yet, but you can copy manually like this:<br>
<br>
1. Find the lv of the new disk<br>
<br>
lvs -o name --select "{IU_<new-disk-uuid>} = lv_tags" vg-name<br>
<br>
2. Activate the lv<br>
<br>
lvchange -ay vg-name/lv-name<br>
<br>
3. Copy the data from the lun<br>
<br>
qemu-img convert -p -f raw -O raw -t none -T none<br>
/dev/mapper/xxxyyy /dev/vg-name/lv-name<br>
<br>
4. Deactivate the disk<br>
<br>
lvchange -an vg-name/lv-name<br>
<span class="HOEnZb"><font color="#888888"><br>
Nir<br>
</font></span></blockquote></div><br></div></div>