On Jan 12, 2010, at 2:54 PM, Ed Spencer wrote: > We have a zpool made of 4 512g iscsi luns located on a network appliance. > We are seeing poor read performance from the zfs pool. > The release of solaris we are using is: > Solaris 10 10/09 s10s_u8wos_08a SPARC > > The server itself is a T2000 > > I was wondering how we can tell if the zfs_vdev_max_pending setting is > impeding read performance of the zfs pool? (The pool consists of lots of > small files).
zfs_vdev_max_pending is the queue depth for each vdev. ZFS will issue up to 35 I/Os to the vdev [1]. You can check the average queue depth by observing the number of entries in the actv and wait queues in iostat. If the actv+wait << 35, then don't worry about it. [1] changed in b127 to 4-10 with an adjusting algorithm. > And if it is impeding read performance, how do we go about finding a new > value for this parameter? This can be changed on the fly, so it is reasonable to experiment. > > Of course I may misunderstand this parameter entirely and would be quite > happy for an proper explanation! This is rarely the cause of slow response for fast devices, such as NetApp servers. -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
