[SATLUG] lvm2 and raid again

John Pappas j at jvpappas.net
Tue Jan 22 20:33:17 CST 2008

On Jan 21, 2008 10:21 PM, Chris Lemire <good_bye300 at yahoo.com> wrote:

> I wish people would stop suggesting the impossible to me. I'm not going to
> go buy a very expensive raid controller when I haven't got the money
> together yet to pay a ticket. I'm a computer science college student and
> taking calculus 2. I don't have time to earn the money for things that
> everyone tells me to buy.

Understand the irony here: you have very limited resources, but are asking
for a no-holds-barred screamer.  The Disk IO bottleneck is only addressed by
more spindles and/or faster bus, as is disk-based data protection.  You
don't have the ability to add spindles, so I hope that we are talking SATA
at least, if not 3Gb SATA to minimize data bus issues.

You need to consider the cost to replace your data, if your data is worth
more to you than a slight speed increase, then mirror.  Otherwise stripe and
burn critical data to DVDs and stripe.  I was lucky, I ran a stripe for
years with no issues, but I backed my critical data to CDR/DVDR, and now use
Amazon S3.

> What's in striping may fail or corrupt if I understand correctly, but my
> data could be backed up onto non striping partitions. I have 2 disks, and
> I'm not getting more any time soon.

This sentence infers that you are going to be backing up to the same
spindles, so what would be the benefit of having a stripe backup to a
partition on the same spindle as the stripe?  Why not just mirror and be
done with it?

Your read speed increases from mirroring will more than likely offset any
write penalties resulting from the mirroring.

Well, it looks like you have gotten a great deal of input, and now have to
decide for yourself.

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