> I have a setup with a T2000 SAN attached to 90 500GB SATA drives > presented as individual luns to the host. We will be sending mostly > large streaming writes to the filesystems over the network (~2GB/file) > in 5/6 streams per filesystem. Data protection is pretty important, but > we need to have at most 25% overhead for redundancy. > > Some options I'm considering are: > 10 x 7+2 RAIDZ2 w/ no hotspares > 7 x 10+2 RAIDZ2 w/ 6 spares > > Does any one have advice relating to the performance or reliability to > either of these? We typically would swap out a bad drive in 4-6 hrs and > we expect the drives to be fairly full most of the time ~70-75% fs > utilization.
What drive manufacturer & model? What is the SAN configuration? More nodes on a loop can significantly reduce performance as loop arbitration begins to dominate. This problem can be reduced by using multiple loops or switched fabric, assuming the drives support fabrics. The data availability should be pretty good with raidz2. Having hot spares will be better than not, but with a 4-6 hour (assuming 24x7 operations) replacement time there isn't an overwhelming need for hot spares -- double parity and fast repair time is a good combination. We do worry more about spares when the operations are not managed 24x7 or if you wish to save money by deferring repairs to a regularly scheduled service window. In my blog about this, I used a 24 hour logistical response time and see about an order of magnitude difference in the MTTDL. http://blogs.sun.com/relling/entry/zfs_raid_recommendations_space_performance In general, you will have better performance with more sets, so the 10-set config will outperform the 7-set config. -- richard This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
