[no Sun folks replying to this? ok, let me do more spam then...] Scott, thank you so much for the testing spirit and sharing the result with the list! -- We architects can be talking all day long and still don't have any idea how the open things would work on "any box", not just the poster-boy kind of expensive boxes with tons of hardware.
However, I would just like to suggest that the SSD performance gain would be mostly in rates (IOPS), but not throughput (MB/s). If you measure the gain in light of rates, you might be (actually should be, by our architecting theory) much more impressed. [well, only if you care about database applications, beyond just our personal digital media files on company network... :-) ] Please see the testing below, done before the 10/2008 Sun official 7000 SSD availability annoucement, as well as the tech talk by Brendan, a bit long (and less fun than my spam), but I am sure it is worth the time to study. http://blogs.sun.com/brendan/entry/test Best, z ----- Original Message ----- From: "Scott Laird" <sc...@sigkill.org> To: "Richard Elling" <richard.ell...@sun.com> Cc: <zfs-discuss@opensolaris.org>; "Akhilesh Mritunjai" <mritun+opensola...@gmail.com> Sent: Saturday, January 03, 2009 12:02 AM Subject: Re: [zfs-discuss] Unable to add cache device > On Fri, Jan 2, 2009 at 8:54 PM, Richard Elling <richard.ell...@sun.com> > wrote: >> Scott Laird wrote: >>> >>> On Fri, Jan 2, 2009 at 4:52 PM, Akhilesh Mritunjai >>> <mritun+opensola...@gmail.com> wrote: >>> >>>> >>>> As for source, here you go :) >>>> >>>> >>>> http://cvs.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/cmd/zpool/zpool_vdev.c#650 >>>> >>> >>> Thanks. It's in the middle of get_replication, so I suspect it's a >>> bug--zpool tries to check on the replication status of existing vdevs >>> and croaks in the process. As it turns out, I was able to add the >>> cache devices just fine once the resilver completed. >>> >> >> It is a bug because the assertion failed. Please file one. >> http://en.wikipedia.org/wiki/Assertion_(computing) >> http://bugs.opensolaris.org >> >>> Out of curiosity, what's the easiest way to shove a file into the >>> L2ARC? Repeated reads with dd if=file of=/dev/null doesn't appear to >>> do the trick. >>> >> >> To put something in the L2ARC, it has to be purged from the ARC. >> So until you run out of space in the ARC, nothing will be placed into >> the L2ARC. > > I have a ~50G working set and 8 GB of RAM, so I'm out of space in my > ARC. My read rate is low enough for the disks to keep up, but I'd > like to see lower latency. Also, 30G SSDs were cheap last week :-). > > My big problem is that dd if=file of=/dev/null doesn't appear to > actually read the whole file--I can loop over 50G of data in about 20 > seconds while doing under 100 MB/sec of disk I/O. Does Solaris's dd > have some sort of of=/dev/null optimization? Adding conv=swab seems > to be making it work better, but I'm still only seeing write rates of > ~1 MB/sec per SSD, even though they're mostly empty. > > > Scott > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
