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ZFS trim when only some drives are SSDs
- Thread starter uOpt
- Start date
Christopher
Gawd
- Joined
- Sep 16, 2002
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- 634
If you are running FreeBSD 9.2 or later, I believe ZFS trim is enabled by default.
http://www.freebsd.org/releases/9.2R/relnotes.html
You can make sure its on by looking at the sysctl tree vfs.zfs.trim. If enabled is set to 1, it will send trim commands to all drives that support it.
http://www.freebsd.org/releases/9.2R/relnotes.html
You can make sure its on by looking at the sysctl tree vfs.zfs.trim. If enabled is set to 1, it will send trim commands to all drives that support it.
My understanding of this code is that it is only in FreeBSD, so it is not a 'general' question. 
That same understanding is that the code identifies what devices support TRIM (including some trickery to get around devices that claim support but don't actually), so my not-personally-verified opinion would be that yes, it would be fine here, because it is taking the time to identify which devices can do TRIM, which would imply it can handle ones that can't, too. Source of my understanding: http://src.illumos.org/source/xref/freebsd-head/sys/dev/isci/scil/sati_device.c
I hope by 'partially backed by SSD' you mean L2ARC/ZIL, not some SSD data vdevs and some HD data vdevs!
That same understanding is that the code identifies what devices support TRIM (including some trickery to get around devices that claim support but don't actually), so my not-personally-verified opinion would be that yes, it would be fine here, because it is taking the time to identify which devices can do TRIM, which would imply it can handle ones that can't, too. Source of my understanding: http://src.illumos.org/source/xref/freebsd-head/sys/dev/isci/scil/sati_device.cI hope by 'partially backed by SSD' you mean L2ARC/ZIL, not some SSD data vdevs and some HD data vdevs!