On Feb 10, 2008 9:06 AM, Jonathan Loran <[EMAIL PROTECTED]> wrote: > > > Richard Elling wrote: > > Nick wrote: > > > Using the RAID cards capability for RAID6 sounds attractive? > > > > Assuming the card works well with Solaris, this sounds like a > reasonable solution. > > > > Careful here. If your workload is unpredictable, RAID 6 (and RAID 5) for > that matter will break down under highly randomized write loads. There's a > lot of trickery done with hardware RAID cards that can do some read-ahead > caching magic, improving the read-paritycalc-paritycalc-write cycle, but you > can't beat out the laws of physics. If you do *know* you'll be streaming > more than writing random small number of blocks, RAID 6 hardware can work. > But with transaction like loads, performance will suck. > > Jon >
I would like to echo Jon's sentiments and add the following: If you are going to have a mix of workload types or if your IO pattern is unknown, then I would suggest that you configure the array as a JBOD and use raidz. Raid 5 or Raid 6 works best for predictable IOs with well controlled IO unit sizes. How you lay it out depends on whether you need (or want) hot spares. What are your objectives here? Maximum throughput, lowest latencies, maximum space, best redundancy, serviceability/portability, or .... ? Cheers, _J
_______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
