Hi Eff, There are a significant number of variables to work through with dedup and compression enabled. So the first suggestion I have is to disable those features for now so your not working with too many elements.
With those features set aside an NTFS cluster operation does not = a 64k raw I/O block. As well the ZFS 64k blocksize does not = one I/O operation. We may also need to consider the overall network performance behavior and iSCSI protocol characteristics and the Windows network stack. iperf is a good tool to rule that out. What I primarily suspect the issue may be is that write I/O operations are not aligned and are waiting for a I/O completion over multiple vdevs. Alignment is important for write I/O optimization and how the I/O maps at the software raid mode will make a significant impact to the DMU and SPA operations on a specific vdev layout. You may also have an issue with write cache operations, by default large I/O calls such as 64K will not use a ZIL cache vdev, if you have one defined, but will be written directly to your array vdevs which will also include a transaction group write operation. To ensure ZIL log usage with 64k I/O's you can apply the following: edit the /etc/system file with set zfs:zfs_immediate_write_sz = 131071 a reboot is required to activate the system file You have also not indicated what your zpool configuration looks like, that would helpful in the discussion area. It appears that your applying the x4500 as a backup target which means you should (if not already) enable write caching on the COMSTAR LU properties for this type of application. e.g stmfadm modify-lu -p wcd=false 600144F02F22800000004C1D62010001 To help triage the perf issue further you could post 2 'kstat zfs' + 2 'kstat stmf' outputs on a 5 min interval and a 'zpool iostat -v 30 5' which would help visualize the I/O behavior. Regards, Mike http://blog.laspina.ca/ -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
