I agree that the hit you take with software RAID computation of
checksums etc is not that high for home with the systems that's common
these days. Spending a hundred or two extra bucks will get you a decent
enough system to run OpenNAS, or the like quite happily. I'm intrigued
by Coraid's ATA over Ethernet idea, www.coraid.com, but won't get a
chance to try it at work and it's too much dough for home.
I don't even bother with any RAID _at home_, the stuff that's really
important to me is backed up, more than one way. I suppose that I should
move more to a single volume for simplicity, but it's easier in some
ways to have a couple of disks NFS/SMB mounted up everywhere.
Work is another matter all together, we spend VERY large dough with
EMC for their "big box o disks" solution, Fibre channel, SAN, NAS, and
whatever the hell else they sell for centralized storage. For locally
attached disks to servers, we only use HP Proliants, their integrated
RAID controllers seldom give us problems, and frequently allow us to
replace disks on the fly, nobody knows but the person with the dead disk
in their hand, there's a price we pay for that....
It seems to me that Brian's goal is simplicity and cost efficiency, an
OpenNAS box, or the like with software RAID should do the trick. Have
plenty of RAM, and a halfway decent processor, you should be just fine.
Kevin
Brian Henning wrote:
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of Jason Tower
1. the bootloader is installed on the MBR of the first disk only.
if that
disk goes bye bye you're in trouble. sure, you can install lilo/grub on
multiple MBRs but that's a pita and an inelegant solution.
I didn't think of that straight away, but the easy solution would be to have
the OS not stored on the array. Separate itty-bitty cheap HD for the OS.
If it dies, who cares. Reinstall. Uptime is my bottom-most concern;
throughput (on read moreso than write) and data integrity/safety are top, in
that order.
2. some sata chipsets flat out don't work with software raid 5, they will
crash the system hard either during initialization or under heavy
i/o. i've
personally seen this happen on no less than three totally
different systems
with multiple distros.
I guess that would just point to a TIAS situation. I've heard Promise being
called a good name in HD controllers, at any rate.
3. if a disk dies suddenly, the system is gonna crash regardless of raid
because the kernel can no longer communicate with /dev/sdx, it just
disappears. go ahead, set up software raid with hot swap disks then yank
one out while the system is running, see what happens. the data
itself is
probably ok (you'll have a degraded array upon reboot) but
availability is
shot. plus your fstab may no longer be accurate once a disk is removed.
Yeah, but as I said in #1 above, uptime isn't nearly so big a concern. If
the machine crashes, oops. I don't imagine ever writing "live" to the array
(meaning any critical write operations, such as writing while sounds are
being recorded, will be to the workstation, then backed up to the RAID --
system crashes during write during backup, just copy the file again), and a
crash during a read would be a nuisance but less of a nuisance than losing
all the data. It's not like a sudden-death crash is going to (hopefully) be
any more frequent than the sudden-death itself.
there are probably workaround for these issues, or if they don't
bother you
then knock yourself out with software raid. i use it myself if
circumstances justify it. but i've built enough systems to know that
hardware raid exists for a reason. if you want to do the job right get a
3ware card and sleep peacefully.
If this were some kind of 4-9s corporate uber-important server, I'd do
exactly that. But $500 just for the RAID card for this application, I can't
justify. If some day I'm doing sound recording engineering for sufficiently
more people than myself, I might be able to justify it. (-:
Thanks for the input, still! That's just the kind of stuff I am looking to
hear. The good, bad, and ugly.
~B
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