Hi Steve, On Thu, 12 Mar 2026 at 19:16, Steve Yates <[email protected]> wrote:
> Hi Alwin, > > > > All VM disks are set as SSD with discard enabled. > > > > “Run guest-trim after a disk move or VM migration” was not checked. I > didn’t realize that was in there! I don’t think that applies though? Per > https://pve.proxmox.com/pve-docs/chapter-qm.html#qm_qemu_agent : > > “With this enabled, Proxmox VE will issue a trim command to the guest > after the following operations that have the potential to write out zeros > to the storage: > > - moving a disk to another storage > - live migrating a VM to another node with local storage” > > > > …and using Ceph the disk doesn’t move if we migrate a VM…? Plus trim is > being run weekly. Maybe I could stop a VM and move its disk to local > storage and back into Ceph again but that would take quite a lot of time > and seems like little to no gain except maybe a lower object count. > That's what I meant as an alternative. > > > That section also has this note on ext4, matching previous discussions: > “There is a caveat with ext4 on Linux, because it uses an in-memory > optimization to avoid issuing duplicate TRIM requests. Since the guest > doesn’t know about the change in the underlying storage, only the first > guest-trim will run as expected. Subsequent ones, until the next reboot, > will only consider parts of the filesystem that changed since then.” > Exactly that. Even if the in-memory bitmap disappears, the underlying misalignment issue will remain and affect any guest. Cheers, Alwin _______________________________________________ ceph-users mailing list -- [email protected] To unsubscribe send an email to [email protected]
