[SATLUG] Personal RAID 6 array/ LED Monitor

travis+ml-satlug at subspacefield.org travis+ml-satlug at subspacefield.org
Mon Jul 5 17:46:00 CDT 2010

On Mon, Jul 05, 2010 at 03:12:07PM -0700, dondavis at reglue.org wrote:
> > I'm using a 3Ware card - it works wonderfully, much more reliable than
> > software RAID.  I had one problem with it; on soft reboots sometimes
> > it doesn't reset properly.  But lately that hasn't been a problem,
> > and the fix was always a simple power-off and back on.
> How many ports does it have? how many drives did you attach?

At first I got the 4-port:


Later I regretted that and got the 8-port:


I think I have 6 1.5TB drives in there now.

> > I personally use RAID 10 for important data, and I do rsync backups
> > to a RAID 0 partition.  So in a way, I have two layers of redundancy.
> Using a different card? External storage?

Actually, on a "backup file server".  I've got a primary and secondary,
which both do DHCP and DNS as well, so having two suits me well.

Of course nothing really functions without the primary NFS server,
given that /home is located on it, so it's kinda not necessary - you
could use external storage if you wanted, but if you're doing
maintenance it's nice for DHCP leases not to expire, DNS not to fail,
and I configure a non-root user with a home directory on / just in
case I really need to use a computer when NFS /home is down.

You may be tempted to make multiple RAID arrays, or partitions; my
opinion is don't bother, you just end up filling one up and then not
having storage to repartition or reshuffle.  I make exceptions for /,
/var/log, and subversion repo.  Of course if any of the file systems
is a backup file system, you don't need redundancy so it makes sense
to make it RAID 0, and thus, a seperate RAID array, PV, VG and LV (in
LVM terminology).

You wouldn't actually need a RAID controller for RAID 0; LVM does
what you need, as long as you don't need to boot off it.  I use mine
anyway, since it's already there.

Also, reiserfs is much faster to reboot than ext2/3, which tends to
sit there and fsck the disks sometimes at bootup, which is super slow
for multi-TB file systems and annoying when your whole network is
useless until its up.  I use it for _everything_ and it's rock solid.
XFS was unstable last time I checked; it would hang the system during
reboots sometimes with a message about timestamps.

Also consider getting a UPS for your precious data.  I use APC, you
can get them at Office Depot (too heavy to be worth shipping), have a
USB interface, and there is a Linux package for doing clean shutdowns
automatically - this is VERY important if you care about your data.

I personally shifted long ago from RH/FC to Ubuntu for desktops, and
there's a Ubuntu "server edition" (no X11/Xorg) which is perfect for
servers.  Plus, like any Debian derivative, you can upgrade the OS
between major revisions without reinstalling.  In fact, it can be done
remotely, if you don't need to enter a disk crypto password at boot
time.  This makes it ideal for servers IMHO, where you want
availability and recent updates for security purposes.

I also have a "kickstart" script that I can post, I update it every
time I upgrade a system to a new release, and it makes
post-installation configuration automatic... it takes maybe 30 minutes of
my time (about 1-1.5 hrs real time) to reinstall a system from scratch,
so if something gets hosed, the cost of fixing it is small.  At present
all it _doesn't_ do is edit config files (postfix, DNS, DHCP).  The latter
two are in SVN already, so installing them is no big deal.

I personally have my mythbuntu server just a small single-disk
machine, and serve video from the NFS server.  It's not a big deal,
since mythbuntu is quite stable now, but some people care about
fan/HDD noise in their TV room, and I care about stability; my NFS
server does little else.  Some have even gone so far as to use SSDs or
PXE netbooting, so it's completely silent, but I haven't bothered.

Whew!  Lots of typing :-)
A Weapon of Mass Construction
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