RAID can be implemented in hardware or software. Can't speak to all hardware RAID controllers, but NetApp does RAIDDP, and ZFS has RAIDZ2, both of which are double-parity-disk RAID (i.e. Survive 2 disk failures rather than 1).
At the moment ZFS cannot expand a storage pool by single disk increments. You could for example expand a RAIDZ pool by concatenating another RAIDZ set to it, but not by adding a single disk. On 2/27/08 11:44 AM, "Edward Ned Harvey" <[EMAIL PROTECTED]> wrote: >>> I know you can get snapshotting from sun, but can you do >>> dualparity or expand on the fly? >> >> Absolutely. ZFS. That is what we are moving everything to. > > The first one, snapshotting, I am fully convinced, is awesomely supported in > solaris with ZFS. > > The second one, what I'm referring to as "dualparity" is the ability to > sustain 2 simultaneous disk failures without data loss. This is a function > of the hardware raid controller, and not the filesystem. Am I making any > bad assumptions here? I am not aware of any hardware raid controllers that > can safely lose two disks at the same time, except the > netapp/storevault/other enterprise filers. What I'm saying is, it's not > supported like this on a sun xstore solaris zfs machine. Right? > > What I'm referring to as "volume expansion on the fly" is the ability to > incrementally add disks, without degradation of redundancy or downtime. If > I've got 6 disks in a dualparity configuration, controlled by hardware DP > raid (usable capacity of 4 disks assuming no hotspare), I just slap in one > more disk, and increase the size of my FS by 25%. No downtime, no > degradation of redundancy. Perhaps the system runs slow for a couple hours. > This too is not supported in the sun xstore solaris zfs configuration, > right? > > >> Try some xstore's with Solaris 10 + ZFS (x86 of course), we buy >> large batches of SAS 1TB spindles for around $280 and build them >> ourselves. ZFS is also now available on FreeBSD, Linux, and even Mac >> OSX >> if you have an aversion to Solaris > > As it happens, I have no aversion to solaris. It's pretty darn good. And > since I learned ZFS supports this snapshotting, I've been browsing around > and looking at ZFS all around. > > I don't think it's fair to say it's supported in OSX. In OSX, you cannot > format and create a ZFS filesystem, and you can only mount it read-only. > Although read/write variations exist, they are very immature at best. > > Same is true for Linux. Although it's open source, it can't be compiled in > the linux kernel any time soon. Because it's written under CDDL, which > conflicts with GPL. See here: http://en.wikipedia.org/wiki/ZFS#Platforms > > > > _______________________________________________ > bblisa mailing list > [email protected] > http://www.bblisa.org/mailman/listinfo/bblisa --Peter Blog: http://pbgalvin.wordpress.com _______________________________________________ bblisa mailing list [email protected] http://www.bblisa.org/mailman/listinfo/bblisa
