[geeks] The Idea(tm)... Homebrew Terabytes Cheap

[Ken Hansen]

What are you saying, you have 5 drives, and each backup tape is 2 Gig? What about a bigger tape drive (can a 10 Gig drive be *that* expensive)?

As for the frequency of backups, what is the difference between this month's month-end and next months beginning backup?

Finally, IDE drives are not designed to be bounced around like a backup tape is, so you can expect some reliability issues. Also, IDE drives are not carranted/proven to have a given shelf life, like tapes are.

Do you have a legal requirement to retain these backups or simply a business reason? WHat if you lose a backup?

Take a look at the Plan 9 filesystem, and ponder a similar system for you network - less-freqently used file migrate from RAM to HD to Optical backup. The trick is only one copy of a given file is retained anywhere in the system.

A previous employer ran backups to optical drives, overwriting the previous backup, to lower media cost.

But, in the end, I think a large tape drive, maybe hanging off a box with a large enough work area on the local HD to buffer the backups would be a fine solution.
(e.g. if your backup set is 20 Gigabytes, get a cheap IDE RAID solution 2x 20+ Gig IDE drives, hanging off the IDE chain, with a 20 Gig tape drive hanging off a SCSI chain - backups flow from the workstations to the server HD RAID array, then the RAID array is read into the tape drive. The tape gets secured, the RAID array is for "hot" backups, and the total cost shold be a fraction of the $20 you estimated for a "wall" of IDE drives)

HTH,

Ken

-----Original Message-----
From: Jody Stephens [mailto:jodys at tatteredcover.com]
Sent: Friday, April 13, 2001 4:32 PM
To: geeks at sunhelp.org
Subject: [geeks] The Idea(tm)... Homebrew Terabytes Cheap


Here is the deal. Currently we have about 5 DDS-2 tape 
drives, media we get for ~$15 a pop. Problem, we have
to keep all of the tapes for 1 year, after that we
keep month beginnings and month ends. Each machine does
about 2GB uncompressed. 

So we've been trying to think of way to cut costs (we
seem to spend >$5000 yearly for tapes including about a 
%10 failure rate). Some of the things I've looked at are

1. Buying cheap IDE drives, writing to them, pulling them
storing them. Actually this works out to about the same
price, but we get better reliabilty (in theory), quicker
backups and restores. But we have to deal with HD's, which
are not exactlly durable. So that is out.

2. CD-R. Alright except each machine would span more than
1 disc, creating problems if one fails. And dealing with
all those CD's doesn't sound like fun.

3. Optical. Too bloody expensive.

Sooo... My thought.
10 IDE plex at ($460 each)
80 WD 40GB drives ($130 each)
put these in a group of rackmount cases.
Buy a decent machine with a bunch of memory.
Buy a couple of good SCSI cards.

Put these together with Linux (or OS of choice) and
a couple of big slices. Bingo. For less than $20,000
I just got 3.2TB max (probably would be less as 
I would want to make some hot spares and such). That
gets me ~3yrs data. If I'm feeling crazy, I put together
another one at the other store and let them mirror 
(safe from fire).

This wouldn't really need to be a high performance beast,
as data would basically be dribbling in. But I guess with
more busess and some striping it could be a decent performer.
If there is a way to get some drives to sleep, then power 
consumption would drop dramatically. It seems that the
same company also makes a IDE backplane which makes some
sort of hot swapping availble. WD gives a 5 year life span  
to the drive, but by then I'm sure you could just buy the 
new 300GB drives and stick them in (what is that... 240TB,
good lord).

For comparison Sun's A1000 gives 436GB for $22,220.00 or
a nickel a MB compared to $20,000 for this system at
6/10 of a penny per MB

Am I on crack? It just seems wrong.  Do I have some order 
of magnitude wrong here? 
What do you guys think of this?