readd cloud@ list

On Wed, Dec 18, 2019 at 5:32 AM Martin Kolman mkolman@redhat.com wrote:

On Wed, 2019-12-18 at 13:11 +0100, Martin Pitt wrote:

...

Hello Chris,

Chris Murphy [2019-12-17 22:23 -0700]:

...

This desktop@ thread [1] about a slow device restored by enabling fstrim.service, got me thinking about enabling fstrim.timer [2] by default in Fedora Workstation. But I'm curious if it might be desirable in other Fedora Editions, and making it a system-wide change?

This is a function/property of hardware, so it's IMO not desktop specific at all. Servers suffer just as well from hard disks becoming slower.

This will also trim thin LVs on thin pools (if any), right ?

Correct.

So not just hardware, it can even make "software" storage layouts faster & potentially even avoid pool exhaustion in some cases. :)

Maybe. I'm not sure either way if someone would actually notice performance improvements, but it wouldn't make them worse. And yes, potentially avoid pool exhaustion, in particular in under provisioned cases.

I forgot to mention: with qemu/kvm/libvirt VM's, the trim would not get passed down to the backing storage due to default settings. The discard mode "unmap" is supported with a SCSI disk using virtio SCSI controller; I see some curious works/doesn't work with "plain" virtio disk. But when it works, it does pass down to underlying thinp LV and raw files. If anyone is doing raw file backups, or otherwise paying for storage, it could save them some coins. And when it doesn't work, literally nothing happens: the file doesn't get holes punched out, but there's also no corruption (I test these things with a Btrfs scrub; it will consistently always complain if a single metadata or data checksum mismatches).

Anyway, it's an optimization. Pretty well tested elsewhere at this point. And offhand not aware of any liabilities, but thought I'd ask about it before writing up a system wide change proposal.

One thing I see in the Ubuntu fstrim.service unit file that I'm not seeing in the Fedora fstrim.service unit file, is a conditional for containers (line 4). I'm not sure where to ask about that. Maybe upstream systemd?

$ cat /lib/systemd/system/fstrim.service [Unit] Description=Discard unused blocks on filesystems from /etc/fstab Documentation=man:fstrim(8) ConditionVirtualization=!container

[Service] Type=oneshot ExecStart=/sbin/fstrim --fstab --verbose --quiet ProtectSystem=strict ProtectHome=yes PrivateDevices=no PrivateNetwork=yes PrivateUsers=no ProtectKernelTunables=yes ProtectKernelModules=yes ProtectControlGroups=yes MemoryDenyWriteExecute=yes SystemCallFilter=@default @file-system @basic-io @system-service chris@chris-Standard-PC-Q35-ICH9-2009:~$