Need some email/colo service -- recommedations?

[Johannes B. Ullrich]

> Yeah, but hard drives are fragile things

not too bad if (a) they are not used too much and (b) well cooled.
and RAID/mirroring will help (ok. that increases the cost).

>  optical media (cd/dvd) tend
> to be read-only (a minor point, I know -- yes I've heard of cd-rw). 

read only can be an advantage. But for example, my desktop /home is
just 4 Gig and I write it to a DVD-RW each night.

> but are they proven to be as reliable as plain old-fashioned tapes yet?

I know everybody quote the proven reliability of tapes. I had bad
experiences with tapes in the past. These where mostly cheap 'Travan' 
drives. But first of all, retrieving a single file took for ever, and
frequently it failed. I think tapes are considered more reliable because
they are usually used by people that treat them well ;-). I don't see
too many DAT tapes on car dashboards, but plenty of CDs.

Another issue with tapes is that they appear to be changing the
cartridge format every 6 months. I wonder how easy it will be to find a
drive to read a ten year old tape (even if the tape is still in perfect
condition).

NIST came out with a nice guide recently about how to store CDs and DVDs
properly. I have yet to read all the details, but they did identify a
couple of simple things to extend the durability of CDs (e.g.: don't use
stick on labels)

What I am really looking for (and may be I will spend some time working
on): A wrapper around rsync/rcs that will keep various versions so you
can easily retrieve backups for a particular date while saving disk
space (maybe compress everything to save even more space). A colleague
of mine wrote a little perl script to go through our backup system and
replace identical files with links. Works very nice. Also: if anybody
know of good linux software to do incremental backups to CDs/DVDs (given
that usually only less then 1 GByte of your data changes each day. In
particular on a desktop)


-- 
CTO SANS Internet Storm Center               http://isc.sans.org
phone: (617) 837 2807                          jullrich at sans.org 

contact details: http://johannes.homepc.org/contact.htm
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