[BBLISA] RE: storevault / netapp

[Edward Ned Harvey]

> > 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