Hi Bob, >> - “tank" is a raidz2 made up of spinning rust. >> - I want to add a ZIL/Slog comprised of SSDs (INTEL 3700s) >> - Being SSDs, "autotrim=on” should be set (right?) > > It seems to me that the ZIL is not like a filesystem (where data is > continually allocated and freed) and it should be expected to appear to write > to the same regions over and over. The FLASH should do wear-leveling as > erase areas start to wear out due to the number of writes. > > Doing a trim of the ZIL might be counter-productive. Doing a trim of normal > pool disks makes a lot more sense.
Interesting! But the I now have the opposite problem! ;) As there is another zpool that consists a number of SSD-based vdevs (using IronWolf 110s). As you say, this is a good case for "autotrim=on". This zpool also uses a ZIL/SLOG (using the same mirrored pair of Intel DC 3700 SSDs*). If what you say is true, than I’d want to have “autotrim=off” for the log vdev on this pool, right?, so I’m back to wanting to alter the “autotrim” value for specific vdevs. * FWIW, the Intel DC 3700 SSDs are 400 GB, and hence too big for a single ZIL/SLOG. Thus I partitioned each into six 60 GB partitions. I’m using one pair of 60 GB partitions for the SSD-based pool's slog, one pair for the HDD-based pool’s slog, and the remaining four GB partitions are held in reserve for when the first two wear out. Effectively, slog-specific spares. Kent ------------------------------------------ illumos: illumos-discuss Permalink: https://illumos.topicbox.com/groups/discuss/T6ef0a71646a80e63-M676ff95bcd1318cb2ab15b61 Delivery options: https://illumos.topicbox.com/groups/discuss/subscription
