[ale] Build-yer-own NAS server

[Robert Story]

On Thu, 8 Jun 2006 00:03:24 -0400 Sean wrote:
SK> On Wednesday 07 June 2006 22:59, Robert Story wrote:
SK> | Make sure your power supply has enough drive power cables and/or invest
SK> in | some splitters (4 drivers for raid, 1 boot, CD/DVD = 6 connectors).
SK> 
SK> Having been burned by power supplies that were _not_ capable
SK> of delivering their rated wattage, you might want to consider
SK> installing a bigger power supply. Extra drives and the extra
SK> fans to cool them can suck more power can expected.
SK> Stressed out power supplies can cause really flaky things 
SK> to occur.

True. There are some web pages out there that let you specify the
components you are planning on using, and calculate numbers to help with
sizing your power supply. I was surprised to find out that I didn't need a
monster powersupply, like I expected. I think I got numbers in the low 400s,
and ended up buying a 550W power supply.

Which reminds me of a few more issues. First, cooling can indeed be an issue,
so you are going to want a case than can handle 5 drives and a CD/DVD drive.
Don't cheap-out here an get a case that has just enough room, get a case that
can handle more drives. That will let you space the drives out, instead of
jamming them all together. Some of the cases that house lots of drives also
have extra mounting brackets for fans to cool the drives.

You may also want to consider a case that will let you mount then vertically,
instead of horizontally, so the bottom drives aren't adding heat to the top
ones.

Of course, 5 drives + case fan + drive fans + power-supply fan(s) can make a
lot of noice. You might want to look at some of the near-silent power
supplies, and get good quiet fans. Toms hardware has reviews of quiet power
supplies, and places like silent PC have quiet fans.

Also, cabling 6 IDE drives is a PITA. You might want to get some rounded IDE
cables, which are easier to work with (and also won't restrict air flow as
much). Unless you get a monster case, don't do what I did and think longer
cables are better, or you just end up trying to cram the extra length
somewhere inside the case.

Another really important point I forgot to mention in my original message:
MONITOR YOUR DRIVES AND RAID ARRAY. There are several reasons drives are
getting so cheap, and one of them is that quality is down. Drives are coming
with shorter warranties. And of course, anything with moving parts is bound to
fail eventually.

smartd will monitor the drives themselves, watching for the drive correcting
errors or finding bad sectors. Set it up to email you when problems are found.
I also have 5 cron scripts (1 per drive) that have smartd tell the drive to
run a self test (the long one, not the short one). I do one drive per day, so
each drive is tested at least once a week.

Also, monitor you RAID array status. If a drive fails and the spare is being
used, you'll want to know ASAP so you can replace the drive immediately. You
can recover from 1 drive failure, but not 2.


Finally, remember RAID is not a substitute for backing up. As you said you are
consolidating data from other machines, I'd leave the original data on those
machine as long as possible (maybe compressed to free up some space, if
needed). Also, once you get the raid built and sized, buy one more huge drive,
equal to the size of the array, as backup. put it in a different machine, and
use cron+rsync to back it up regularly. You might want to consider having that
drive off-site, say at a friend or relatives place. (It was here on the ale
list that I read about someone who was using a drive in another machine as a
backup, only to have both machines and their drives fried when lightning struck
right outside their office window.)