And am I reading that right, that after a reboot of an ext4 server TRIM will work again just fine, once?
That still seems unrelated to the core issue of the incorrect USED space estimate since that wouldn't apply to Windows, ZFS, etc. Thanks, Steve -----Original Message----- From: Alwin Antreich via ceph-users <[email protected]> Sent: Friday, March 13, 2026 8:52 AM To: Steve Yates <[email protected]> Cc: [email protected] Subject: [ceph-users] Re: Can rbd sparsify be run on a running VM's disk? 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] ------------------------------------ This email has been scanned for spam & viruses. If you believe this email should have been stopped by our filters, click the following link to report it (https://portal.mailanyone.net/index.html#/outer/reportspam?token=dXNlcj1zdGV2ZUB0ZWFtaXRzLmNvbTt0cz0xNzczNDA5OTA1O3V1aWQ9NjlCNDE2NzFEQTIwMDY4QTYzQTRBQzcyNTE2Qzg5NDg7dG9rZW49ZGE4MTczMzFlOWZiYzIyZTQyMjQ3NzYxNDExMWFjOGRlZmJjYTg2Njs%3D). _______________________________________________ ceph-users mailing list -- [email protected] To unsubscribe send an email to [email protected]
