On Mon, Sep 23, 2019 at 2:29 PM <[email protected]> wrote: > Jerry, just some thoughts regarding this important subject. > > TRIM is for SATA disks and UNMAP for SAS / SCSI ? >
Yes, that's right, however, this is exposed at the ZFS CLI as the "trim" subcommand for all types. Currently, we only have sd driver support for UNMAP. As far as I know, we don't have any support for SATA TRIM right now, but that is something someone could add. If anyone is particularly interested in this, it would be great to see them do that work. > There are also some SSD SAS disks which, as it seems, work very fine with > or without periodic garbage collection. > For exemple the HGST HUSSL40x0BSS60x, cf. > https://www.storagereview.com/hitachi_ultrastar_ssd400sb_enterprise_ssd_review > Here, Hitachi has implemented a couple of technologies (huge internal > overprovisioning, if my understanding is right) in order to make these > disks work under any OS and in any situation. > Do you have any information about this ? I have heard that trim is not an issue for most modern enterprise-class SSDs, but is mostly useful for commercial-grade parts. However, I am not an expert on this. My understanding is also, that Oracle recommends at the moment not to > activate the periodical garbage collection algorithm (based on unmap) on > Solaris 11.x. > > And finally, it seems that ESXi 6.7 implements such an algorithm which is > reported to work well. > It seems even to be possible to clean older disks SATA/SAS SSD under ESXi > in order to restore their original performance. Once I have a better understanding of all of the issues with the ZFS trim code path, I'll get bugs filed and work on getting those fixed. I'm out of the office this week though, so there won't be any progress until at least next week. Thanks, Jerry Permali > <https://illumos.topicbox.com/groups/developer/Tcbded5fafc0f4724-Mbe79e75a6c86c035dd9d3775> > ------------------------------------------ illumos: illumos-discuss Permalink: https://illumos.topicbox.com/groups/discuss/Tcbded5fafc0f4724-M3775b4f7e66f6212444c6750 Delivery options: https://illumos.topicbox.com/groups/discuss/subscription
