Ok, makes sense. What other kind of indicators can I look at? I get decent results from DD but still feels a bit slow...
Compression lz4 should not slow it down right? Cpu is not doing much when copying data over, maybe 15% busy or so... Sync=always, block size 1M 204800000000 bytes (205 GB) copied, 296.379 s, 691 MB/s real 4m56.382s user 0m0.461s sys 3m12.662s Sync=disabled, block size 1M 204800000000 bytes (205 GB) copied, 117.774 s, 1.7 GB/s real 1m57.777s user 0m0.237s sys 1m57.466s ... while doing this I was looking at my FIO cards, I think the reason is that the SLC's need more power to deliver higher performance, they are supposed to deliver 1.5GB/sec but only delivers around 350MB/sec each.... Now looking for aux power cables and will retest... Br, Rune -----Original Message----- From: Richard Elling [mailto:richard.ell...@richardelling.com] Sent: Friday, October 31, 2014 9:03 AM To: Eric Sproul Cc: Rune Tipsmark; omnios-discuss@lists.omniti.com Subject: Re: [OmniOS-discuss] zfs pool 100% busy, disks less than 10% On Oct 31, 2014, at 7:14 AM, Eric Sproul <eric.spr...@circonus.com> wrote: > On Fri, Oct 31, 2014 at 2:33 AM, Rune Tipsmark <r...@steait.net> wrote: > >> Why is this pool showing near 100% busy when the underlying disks are >> doing nothing at all.... > > Simply put, it's just how the accounting works in iostat. It treats > the pool like any other device, so if there is even one outstanding > request to the pool, it counts towards the busy%. Keith W. from > Joyent explained this recently on the illumos-zfs list: > http://www.listbox.com/member/archive/182191/2014/10/sort/time_rev/pag > e/3/entry/18:93/20141017161955:F3E11AB2-563A-11E4-8EDC-D0C677981E2F/ > > The TL;DR is: if your pool has more than one disk in it, the pool-wide > busy% is useless. FWIW, we use %busy as an indicator that we can ignore a device/subsystem when looking for performance problems. We don't use it as an indicator of problems. In other words, if the device isn't > 10% busy, forgetabouddit. If it is more busy, look in more detail at the meaningful performance indicators. -- richard _______________________________________________ OmniOS-discuss mailing list OmniOS-discuss@lists.omniti.com http://lists.omniti.com/mailman/listinfo/omnios-discuss