Hi Bob, On 2/15/08 12:13 PM, "Bob Friesenhahn" <[EMAIL PROTECTED]> wrote:
> I only managed to get 200 MB/s write when I did RAID 0 across all > drives using the 2540's RAID controller and with ZFS on top. Ridiculously bad. You should max out both FC-AL links and get 800 MB/s. > While I agree that data is sent twice (actually up to 8X if striping > across four mirrors) Still only twice the data that would otherwise be sent, in other words: the mirroring causes a duplicate set of data to be written. > it seems to me that the load balancing should > still work for one application write since ZFS is what does the > multiple device I/Os. Depends on how the LUNs are used within the pool, but yes that's what you should expect in which case you should get 400 MB/s writes on one file using RAID10. >> If you do the mirroring on the RAID hardware you¹ll get double that speed on >> writing, or 400MB/s and the bottleneck is still the single FC-AL interface. > > I didn't see that level of performance. Perhaps there is something I > should be investigating? Yes, if it weren't for the slow FC-AL in your data path you should be able to sustain 20 x 130 MB/s = 2,600 MB/s based on the drive speeds. Given that you're not even saturating the FC-AL links, the problem is in the hardware RAID. I suggest disabling read and write caching in the hardware RAID. - Luke _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
