Summary of Re: Experiences with 4D/2xx as timesharing systems?

[Jean-Francois Lamy]

In article <8904131500.AA20088 at adt.uucp> adt!madd at bu-it.bu.edu (jim frost) writes:
>>Nothing that goes through the filesystem (tar, cpio, bru) is an acceptable
>>backup program in a large installation.
>
>That's not so.  It is possible (even pretty easy) to build a very
>good, very reliable backup program which works through the filesystem.

Restoring access times properly is needed (without an additional system call
and losing the ctime information).  Dealing with files with holes is also
mildly tricky (you do want restores of a dumped fs to fit back :-).  But most
of all, I don't think incurring the overhead of going through the file system
is justifiable once you have large amounts of disk space.

We've had a very busy Sun 4 go down a couple of times a month, dragging with
it half of its partitions each time (bug in SunOS, that appears to have been
fixed now).  So we care *a lot* about backups. On all our machines we run a
home grown incremental backup program 3 times a day and an incremental dump to
disk every night, in addition to full tape dumps at least once a week.  And
believe us, all that paranoia has not been wasted...

Jean-Francois Lamy               lamy at ai.utoronto.ca, uunet!ai.utoronto.ca!lamy
AI Group, Department of Computer Science, University of Toronto, Canada M5S 1A4