On Oct 16, 2011, at 3:56 AM, Jim Klimov wrote: > 2011-09-29 17:15, Zaeem Arshad пишет: >> >> >> On Thu, Sep 29, 2011 at 11:33 AM, Garrett D'Amore <garrett.dam...@gmail.com> >> wrote: >> >> >> I think he means, resilver faster. >> >> SSDs can be driven harder, and have more IOPs so we can hit them harder with >> less impact on the overall performance. The reason we throttle at all is to >> avoid saturating the bandwidth of the drive with resilver which would >> prevent regular operations from making progress. Generally I believe >> resilver operations are not "bandwidth bound" in the sense of pure >> throughput, but are IOPs bound. As SSDs have no seek time, they can handle >> a lot more of these little operations than a regular hard disk. >> >> - Garrett >> >> >> >> What's the throttling rate if I may call it that? >> > > IIRC about 7MBps, and I guess it is hardcoded since the value > is so well known as to have been reported several times.
No, the resilver throttling is more based on IOPS than bandwidth. > I think another rationale for SSD throttling was with L2ARC tasks - > to reduce probable effects of write overdriving in SSD hardwares > (less efficient and more wear on SSD cells). L2ARC fill rate is, by default in most distros, 16MB/sec until full, then 8MB/sec. -- richard -- ZFS and performance consulting http://www.RichardElling.com VMworld Copenhagen, October 17-20 OpenStorage Summit, San Jose, CA, October 24-27 LISA '11, Boston, MA, December 4-9 _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
