Just for reference: I have tested an Intel DC 3500 SSD as an slog device today - from a CentOS KVM guest doing dd with 64k block size.
Average write speed 270MB/s - I think that speaks for itself. On Jan 19, 2015 8:18 PM, "Robert Mustacchi via smartos-discuss" < [email protected]> wrote: > On 1/18/15 23:16 , Robert Mustacchi via smartos-discuss wrote: > > On 1/18/15 19:52 , Greg Zartman via smartos-discuss wrote: > >> On Sun, Jan 18, 2015 at 5:36 PM, Ian Collins <[email protected]> wrote: > >> > >>> Are you using the 200G 3700s because of the increased performance over > the > >>>> 100G 3700s? > >>>> > >>> > >>> Yes, they have double the IOPs. > >> > >> > >> Thanks Ian. I'll add one of these SSDs to my zpool and report back. > The > >> current setup is 8x1TB western digital drives configured in 4 sets of > raid > >> 1 mirrors. I have twin SAS cards in this box cross-flashed to work well > >> with ZFS. This should be about the fastest config we can get. > > > > While it's obvious that if you're doing a lot of synchronous writes that > > doing disk I/O and waiting for it to synch to normal hard drives will be > > a bottleneck, you'll want to make sure that's actually the case. > > > > In general, the wins from a slog are worth it; however, it's important > > to always verify *where* your performance problems ultimately are coming > > from. So, just make sure you do do that. You'd have to be in a case > > where, for example, you set a cpu share or cap that was causing > > excessive throttling and LAT. > > Sigh, *hate to be in a case. > > But tl;dr, the slog will almost certainly help you, can't hurt you, but > don't forget to measure. > > Robert > > > > ------------------------------------------- > smartos-discuss > Archives: https://www.listbox.com/member/archive/184463/=now > RSS Feed: > https://www.listbox.com/member/archive/rss/184463/26861862-3392afaa > Modify Your Subscription: > https://www.listbox.com/member/?&; > Powered by Listbox: http://www.listbox.com > ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
