I observed something like this a while ago, but assumed it was something I did. (It usually is... ;)
Tell me - If you watch with an iostat -x 1, do you see bursts of I/O then periods of nothing, or just a slow stream of data? I was seeing intermittent stoppages in I/O, with bursts of data on occasion... Maybe it's not just me... Unfortunately, I'm still running old nv and xen bits, so I can't speak to the 'current' situation... Cheers. Nathan. Martin wrote: > Hello > > I've got Solaris Express Community Edition build 75 (75a) installed on an > Asus P5K-E/WiFI-AP (ip35/ICH9R based) board. CPU=Q6700, RAM=8Gb, > disk=Samsung HD501LJ and (older) Maxtor 6H500F0. > > When the O/S is running on bare metal, ie no xVM/Xen hypervisor, then > everything is fine. > > When it's booted up running xVM and the hypervisor, then unlike plain disk > I/O, and unlike svm volumes, zfs is around 20 time slower. > > Specifically, with either a plain ufs on a raw/block disk device, or ufs on a > svn meta device, a command such as dd if=/dev/zero of=2g.5ish.dat bs=16k > count=150000 takes less than a minute, with an I/O rate of around 30-50Mb/s. > > Similary, when running on bare metal, output to a zfs volume, as reported by > zpool iostat, shows a similar high output rate. (also takes less than a > minute to complete). > > But, when running under xVM and a hypervisor, although the ufs rates are > still good, the zfs rate drops after around 500Mb. > > For instance, if a window is left running zpool iostat 1 1000, then after the > "dd" command above has been run, there are about 7 lines showing a rate of > 70Mbs, then the rate drops to around 2.5Mb/s until the entire file is > written. Since the dd command initially completes and returns control back > to the shell in around 5 seconds, the 2 gig of data is cached and is being > written out. It's similar with either the Samsung or Maxtor disks (though > the Samsung are slightly faster). > > Although previous releases running on bare metal (with xVM/Xen) have been > fine, the same problem exists with the earlier b66-0624-xen drop of Open > Solaris > > > This message posted from opensolaris.org > _______________________________________________ > 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
