[ovirt-users] Re: new cluster, 6 nodes

1) If you have a hardware RAID you want to use, you should just use NFS / Direct SCSI / FibreChannel on top of it and forgo Gluster. As it's been reported on the list that Gluster has latency issues when dealing with a hardware RAID. Makes sense considering that Gluster is essentially a software RAID. Using both is redundant, and counter productive. (As a bad write on Gluster won't be detected / show up on hardware and vice versa.) Throwing Gluster on top of LVM on top of a hardware RAID, is not something I'd recommend. You've got way to many layers of abstraction there and it will be a huge pain to debug, or perform data recovery, if something goes wrong later. Not to mention all of the resources spent trying to figure out what data block goes where. (Don't forget that each VM adds another layer of abstraction for it's virtual harddisk paritions / filesystem.) LVM and a hardware RAID perform virtually all of the tasks Gluster would offer you. If having a fail over node is important to you, I'd just drop the hardware RAID and use Gluster. I personally don't use LVM, as I find it to be the source of a lot of unnecessary headaches, but you can use it with Gluster without penalty. Gluster, in my opinion, tends to work best without abstraction layers underneath it. You can use LVM, but I personally would prefer physical partitions / disks for the bricks. As there is less chance of LVM grabbing the wrong partitions and causing a boot to emergency mode. (Which is reported on the list a lot.) Granted that's not fesible in many cases, but I consider it when Gluster is involved. 2) If you choose to use Gluster, the only thing you'll really lose by doing a 3 node pool to start with is the time to replicate to the new bricks after adding them. Although, if you want to test how things work with your hardware RAID you may want to start with all 6, so that you can get accurate measurements, especially latency, for real usage. -Patrick Hibbs On Tue, 2022-05-31 at 03:14 +0000, bpbp(a)fastmail.com wrote: