Hey Brian The log device is not used and you're seeing high latency from iSCSI? I've actually seen that log devices can be a choke point for throughput oriented workloads if for example your disks in aggregate can stream data faster than your small number of log devices. This is why we created the logbias property..
Adam -- Adam Leventhal CTO, Delphix Sent from my mobile On Sep 3, 2014, at 8:51 AM, Brian Menges <[email protected]> wrote: > Are these dtrace tools available to FreeBSD? I'm trying to solve/improve some > throughput performance on zvol across iscsi. I have observed that the log > device isn't in use at all across iscsi... very sad indeed. > > Anyone have some other tuning and settings for a high-ram freebsd system? > We're running both fbsd9 and fbsd10. I'm trying to tune for random write > performance. > > Thanks for this article. It's a good read. > > - Brian Menges > > -----Original Message----- > From: Steven Hartland via illumos-zfs [mailto:[email protected]] > Sent: Wednesday, September 03, 2014 1:31 AM > To: Adam Leventhal; developer; [email protected] > Subject: [zfs] Re: [OpenZFS Developer] OpenZFS write throttle tuning > > ----- Original Message ----- > From: "Adam Leventhal" <[email protected]> > > >> Hey folks, >> >> I finished up a long-overdue post on tuning the OpenZFS write >> throttle. I hope this is a useful guide for those of you optimizing >> OpenZFS-based systems. >> >> http://dtrace.org/blogs/ahl/2014/08/31/openzfs-tuning/ > > Nice Adam thanks for this, very informative :) > > For those interested FreeBSD has one extension to this in that > it also min_active and max_active for TRIM specifically: > vfs.zfs.vdev.trim_min_active: 1 > vfs.zfs.vdev.trim_max_active: 64 > > The size of trim_max_active may seem high compared to the > others but this is due to the fact that up to 64 individual > TRIM requests can be combined at the CAM layer into a single > device request, hence the threshold at which it starts to > impact latency is higher than that for reads and writes. > > Regards > Steve > > > ------------------------------------------- > illumos-zfs > Archives: https://www.listbox.com/member/archive/182191/=now > RSS Feed: https://www.listbox.com/member/archive/rss/182191/24656803-110351fd > Modify Your Subscription: > https://www.listbox.com/member/?member_id=24656803&id_secret=24656803-8d47bc7a > Powered by Listbox: http://www.listbox.com > > ________________________________ > > The information contained in this message, and any attachments, may contain > confidential and legally privileged material. It is solely for the use of the > person or entity to which it is addressed. Any review, retransmission, > dissemination, or action taken in reliance upon this information by persons > or entities other than the intended recipient is prohibited. If you receive > this in error, please contact the sender and delete the material from any > computer. _______________________________________________ developer mailing list [email protected] http://lists.open-zfs.org/mailman/listinfo/developer
