> > I think the point is to say: ZFS software raid is both faster and > more > > reliable than your hardware raid. Surprising though it may be for a > > newcomer, I have statistics to back that up, > > Can you share it?
Sure. Just go to http://nedharvey.com and you'll see four links on the left side, "RAID Benchmarks." The simplest comparison is to look at Bob's Method Summary. You'll see statistics for example: raidz-5disks raid5-5disks-hardware You'll see that it's not a 100% victory for either one - the hardware raid is able to do sequential writes faster, and stride reads faster, but all the other categories, the raidz is faster, and by a larger margin. If all categories are equally important in your usage scenario, then the average is 3.53 vs 2.47 in favor of zfs raidz. But if your usage characteristics don't weight the various operations equally ... Most people care about random reads and random writes more than they care about other operations ... then the results are 2.18 vs 1.52 in favor of zfs raidz. As for "more reliable" ... Here's my justification for saying that. For starters, one fewer single point of failure. If you're doing RAID with your HBA, and if it dies, then you risk losing your whole data set, regardless of raid and the fact that the disks are still good. Also, you can't attach your disks to some other system to recover your data; you need to replace your HBA with an identical HBA to even stand a chance. But if you're doing ZFS raid, there is no HBA that can die. Suppose if you needed to, you could attach your disks to another system and simply import the zfs datasets. > > You will do best if you configure the raid controller to JBOD. > > Problem: HP's storage controller doesn't support that mode. Sure it does. You just make a RAID0 or RAID1 with a single disk in it. And make another. And make another. Etc. This is how I do it on a Dell PERC. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
