** Andrew Savory lists@andrewsavory.com [2003-07-21 13:36]:
MJ Ray wrote:
Anyone like to comment on that compared to LVM, RAID or other normal backup methods?
Anyone else uncomfortable with the use of the words "LVM, RAID" in a sentence about normal backup methods?
Disk mirroring or striping is NOT backup - it's failover/redundancy.
** end quote [Andrew Savory]
Aboslutely, and never let a Compaq (oh, they don't exist anymore, I wonder if HP are the same) engineer near your server without very close supervision. I had a situation a few years back where a drive had gone on a server and another was on the way out, so as it was still under warranty the Compaq engineer came in to 'fix' it. This should have been very straightforward as it was hot-pluggable hardware RAID. The complication was that the engineer and server were in the US and we were in the UK.
It should have gone:
- Remove duff HD and wait for rebuild of drive - Once rebuild complete we notify the engineer rebuild complete - Remove flaky unit and let that rebuild
It actually went:
- Remove duff HD and wait for rebuild of drive - Lights stopped flashing on the front of the machine so the engineer decided it had finished - Remove flaky unit and let machine die horribly and corrupt all data
Now if he had waited for our confirmation all would have been fine - I mean surely he shouldn't have assumed that if the lights stopped flashing it was complete!
Hence we resorted to backup to rebuild the server - iirc the local support person put NT (spit) back on and we finished the config over the WAN, I don't think we ended up flying anyone out there!
Of course unless you have at least 20 levels of backup things can still go wrong - I've been unlucky enough to have 3 levels of backup fail on me at the same time:
local HD for quick recovery of deleted files - this drive died locally attached HD for backup - this drive also died, but differently tape backup - this was no longer readable as the index was on the dead HD and the new installation (Win2k I'm afraid) was unable to rebuild the contents because it couldn't read the tape (same drive, checked and verified backup, unable to read following rebuild and reinstall of server on new HD - no other hardware changed or in any way reconfigured). Thankfully apart from being significant in volume it wasn't significant in content - just requires a good amount of downloading to recover it when I need access again :-(