The advantage is that your data is still being checksumed in zfs and not
using the pseudo-hardware raid. For example, (and it happened to one of
sun's engineers, IIRC) lets say your power supply starts to fail, only
rather then just powering off the machine, it gives wildly fluctuating
power. This causes the disks to not consistently write bits correctly. In
your "hardware" raid you do not have enough information to correct the
problem. Sure, you have a correct copy on one of the disks, but you don't
know WHICH one is the correct one. Using zfs you know which is bad (it will
fail checksum) and it can automatically be corrected.
There are a list of other situations that this type of data-corruption can
occur. Non-catostrophic drive failure, incoming cosmic rays, etc. Depending
on where the data is lost, the effect can be anything from none at all to a
non-useable kernel. Sure damage is unlikely, but possible, so why not
check?
Andrew Hettinger
http://Prominic.NET || [EMAIL PROTECTED]
Tel: 866.339.3169 (toll free) -or- +1.217.356.2888 x.110 (int'l)
Fax: 866.372.3356 (toll free) -or- +1.217.356.3356 (int'l)
Mobile direct: 1.217.621.2540
CompTIA A+, CompTIA Network+, MCP
[EMAIL PROTECTED] wrote on 09/11/2008 04:39:57 AM:
> 2008/9/9 Andrew M. Hettinger:
> > I agree with James Dean, there is no need (or indeed, benefit) to use
the
> > psudo-hardware raid. I'm not sure on indiana, but nevada will just
install
> > onto a mirrored zfs now (since snv_91 I think), or you can follow the
steps
> > he outlines:
>
> Thanks for that. I can see the advantage in using clever ZFS wizardy
> with raidz/2 methods, but when it comes to just a simple 2-disk mirror
> set for the operating system i'm struggling to see any advantage in
> not using hardware mirroring. It's a completely 'hands off' solution
> (apart from swapping a disk out)!
>
> If anyone is interested, from the discussions on this thread, I
> committed and ordered my SAN/NAS hardware last night :-
>
> Intel S3210SHLX Server Board (Dual intel gigE)
> Intel Dual Core E7200 (45nm) CPU
> 4GB DDR2 RAM
> AOC-SAT2-MV8 8-port SATA controller
> 8 x Samsung F1 1TB SATA HD's (for zfs pool)
> 2 x Seagate 40GB (for o/s)
>
> Hopefully this will all work perfectly :-)
> _______________________________________________
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