NateroniPizza
Dabbler
- Joined
- Dec 19, 2022
- Messages
- 14
I keep seeing metadata-only L2ARC being offhandedly thrown around as a safe alternative to metadata VDEVs, but I've never seen anyone actually post comparisons about their performance or behavior. I've tried both over the last week or so (switching back and forth a few times, rebuilding the pool as necessary), and I've not been able to get L2ARC to work as an actual replacement for a metadata special VDEV. Note that I've got a pair of Optane P1600X drives I had purchased specifically for the purpose of a metadata special VDEV mirror, but given the advantages I've more recently read (safer + ability to remove it), I'd really like to get it working as metadata-only L2ARC if at all possible.
When I do a "/bin/ls -lahR /mnt/", I get a sub-2 minute list time when I have a metadata special VDEV set up. However, regardless how I configure it, I cannot get the persistent L2ARC to get under 18 minutes on a fresh boot (subsequent times running it before the next reboot is extremely fast, of course, as it is then cached in ARC).
I've tried both secondarycache=all and secondarycache=metadata.
I have both l2arc_noprefetch=0 and l2arc_headroom=0. Also, as I am running TrueNAS Scale, l2arc_rebuild_enabled is enabled by default.
I've verified after a reboot that these settings took, using arc_summary and zfs get secondarycache {poolname}.
How does one get this so-often-recommended metadata special VDEV-alternative to actually work as a metadata special VDEV alternative? It's very possible I'm doing something wrong, but given how often this is mentioned without any caveats, I would have thought it would work without any additional configuration.
When I do a "/bin/ls -lahR /mnt/", I get a sub-2 minute list time when I have a metadata special VDEV set up. However, regardless how I configure it, I cannot get the persistent L2ARC to get under 18 minutes on a fresh boot (subsequent times running it before the next reboot is extremely fast, of course, as it is then cached in ARC).
I've tried both secondarycache=all and secondarycache=metadata.
I have both l2arc_noprefetch=0 and l2arc_headroom=0. Also, as I am running TrueNAS Scale, l2arc_rebuild_enabled is enabled by default.
I've verified after a reboot that these settings took, using arc_summary and zfs get secondarycache {poolname}.
How does one get this so-often-recommended metadata special VDEV-alternative to actually work as a metadata special VDEV alternative? It's very possible I'm doing something wrong, but given how often this is mentioned without any caveats, I would have thought it would work without any additional configuration.