[ovirt-users] Re: oVirt + TrueNAS: Unable to create iSCSI domain - I am missing something obvious

David do yourself a favor a move away from NFS on TrueNAS for VM hosting. As a personal experience hosting VMs on NFS may cause your entire infrastructure to be down if you change something on TrueNAS, even adding a new NFS share may trigger a NFS server restart and suddenly all your VMs will be trashed. Emphasis on _may_. I’ve been using the product since FreeNAS 8, which was 2012 and that’s observed behavior. Also oVirt has its quirks with iSCSI, mainly on MPIO (Multipath I/O) but as for the combination with TrueNAS just stick with iSCSI. Sent from my iPhone On 3 Mar 2022, at 00:02, David Johnson <djohnson(a)maxistechnology.com&gt; wrote:  The cluster is on nfs today, with 500gb NVME SiLOG. Under heavy IO the vm's are thrown into paused state instead of iowait. A prior email chain identified a code error in qemu, with a repro using nothing more than DD to set 2 gb on the virtual disk to 0's . Since the point of the system is to handle massive IO workloads, this is obviously not acceptable. If there is a way to make the nfs Mount more robust I'm all for it over the headaches that go with managing block io. On Wed, Mar 2, 2022, 8:46 AM Nir Soffer <nsoffer(a)redhat.com&gt; wrote: > On Wed, Mar 2, 2022 at 3:01 PM David Johnson < > djohnson(a)maxistechnology.com&gt; wrote: > >> Good morning folks, and thank you in advance. >> >> I am working on migrating my oVirt backing store from NFS to iSCSI. >> >> *oVirt Environment:* >> >> oVirt Open Virtualization Manager >> Software Version:4.4.4.7-1.el8 >> >> *TrueNAS environment:* >> >> FreeBSD truenas.local 12.2-RELEASE-p11 75566f060d4(HEAD) TRUENAS amd64 >> >> >> The iSCSI share is on a TrueNAS server, exposed to user VDSM and group >> 36. >> >> oVirt sees the targeted share, but is unable to make use of it. >> >> The latest issue is "Error while executing action New SAN Storage >> Domain: Volume Group block size error, please check your Volume Group >> configuration, Supported block size is 512 bytes." >> >> As near as I can tell, oVirt does not support any block size other than >> 512 bytes, while TrueNAS's smallest OOB block size is 4k. >> > > This is correct, oVirt does not support 4k block storage. > > >> >> I know that oVirt on TrueNAS is a common configuration, so I expect I am >> missing something really obvious here, probably a TrueNAS configuration >> needed to make TrueNAS work with 512 byte blocks. >> >> Any advice would be helpful. >> > > You can use NFS exported by TrueNAS. With NFS the underlying block size > is hidden > since direct I/O on NFS does not perform direct I/O on the server. > > Another way is to use Managed Block Storage (MBS) - if there a Cinder > driver that can manage > your storage server, you can use MBS disks with any block size. The block > size limit comes from > the traditional lvm based storage domain code. When using MBS, you use > one LUN per disk, and > qemu does not have any issue working with such LUNs. > > Check with TrueNAS if they support emulating 512 block size of have > another way to > support clients that do not support 4k storage. > > Nir > _______________________________________________ Users mailing list -- users(a)ovirt.org To unsubscribe send an email to users-leave(a)ovirt.org Privacy Statement: https://www.ovirt.org/privacy-policy.html oVirt Code of Conduct: https://www.ovirt.org/community/about/community-guidelines/ List Archives: https://lists.ovirt.org/archives/list/users@ovirt.org/message/6NLGE4Q2ABJ...