Hi, I think what's being suggested here is to create a good old LVM VG in a virtualized guest, from multiple RBDs, each accessed as a separate VirtIO SCSI device. As each storage device in the LVM VG has its own queues at the VirtIO / QEMU / RBD interface levels, that would allow for greater parallel performance. Loris Cuoghi On 21/01/21 15:15, huxiaoyu@horebdata.cn wrote:
Does Ceph now supports volume group of RBDs? From which version if any?
regards,
samuel
huxiaoyu@horebdata.cn
From: Robert Sander Date: 2021-01-21 10:57 To: ceph-users Subject: [ceph-users] Re: Large rbd Hi,
Am 21.01.21 um 05:42 schrieb Chris Dunlop:
Is there any particular reason for that MAX_OBJECT_MAP_OBJECT_COUNT, or it just "this is crazy large, if you're trying to go over this you're doing something wrong, rethink your life..."?
IMHO the limit is there because of the way deletion of RBDs work. "rbd rm" has to look for every object, not only the ones that were really created. This would make deleting a very very large RBD take a very very long time.
Rather than a single large rbd, should I be looking at multiple smaller rbds linked together using lvm or somesuch? What are the tradeoffs?
IMHO there are no tradeoffs, there could even be benefits creating a volume group with multiple physical volumes on RBD as the requests can be bettere parallelized (i.e. virtio-single SCSI controller for qemu).
Regards