[K12OSN] Need Help

"Terrell Prudé Jr." microman at cmosnetworks.com
Tue Jul 10 06:40:25 UTC 2007

Krsnendu dasa wrote:
>> 6)Please use RAID 1 on your server. This is slower for writes
>> (installation and saving files) but allows simultaneous seeks for
>> simultaneous users/pocesses. Hard drives are about 25 cents a gB for
>> 500 gB.
>>   RAID 1 certainly works, but if he can afford it, RAID 5 will be
>> even quicker due to more spindles.
> Are you sure? I have heard that RAID 5 is no good.
> http://www.baarf.com/ 

I just looked at this.  Whoever these people are, they look to me to be
ranting.  It seems that, to them, nothing short of a multi-node cluster
filesystem would be enough for your average small-office file server! 
How easy it is to spend other people's money, eh?  :-)

The only time I've ever heard of a RAID 5 having any problems is when
the sysadmin didn't set it up right, in which case he gets what he
deserves.  The problem of drives failing is an issue with *any* array,
even an "array" of one.  That's why we do parity checking.  At work, we
routinely run 14-disk arrays in a RAID 5 configuration, and we've yet to
have a problem related to running in RAID 5.  And as for the "slows
things down" issue, I'll say this:  nothing--NOTHING--beats RAID 0 for
speed.  That said, RAID 5 kicks RAID 1 in the delicate parts when it
comes to performance.  Again, we're back to, say, six or eight spindles
vs. two spindles; no contest.  I've run many 14-disk SCSI RAID 5 setups,
and my God, they were quick!!  Yes, I'm assuming a real hardware RAID
card here; I generally don't recommend software RAID, no matter which
RAID level you use.

Throughout my years of being a sysadmin, I've found RAID 5 to be the
best all-around RAID level to use.  Reliability, cost, performance--it's
all there.  Now, I've had a couple of RAID *cards* fail on me...but
that's irrespective of your chosen RAID level.  Swap the card and keep

Now, if you want to start getting really fancy, for example, to RAID 10
or 50, you'd better get a *whole* lot more disks and a *whole* lot more
physical space to put them.  Oh, and it'll therefore cost a lot more
coin, too.  The only folks who need that are folks running massive
databases--or really huge file/Web servers--that need, say, 99.9999%
uptime, e. g. www.dell.com or www.orbitz.com.


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