Marc,

Thanks for your feedback!

Main question: What is an example of a "good" default configuration for a "hard drive" amanda backup server?

There's no general configuration for all kind of networks/server. But a good start is http://wiki.zmanda.com/index.php/How_To:Set_Up_Virtual_Tapes

4. Would this lay-out be OK for a server that would back-up clients to /backup, and also back its own root partition to /backup? Otherwise, what is a good default layout, or what are you using that works well for you?

/dev/md10   /                          (2x 1TB raid 1)
/dev/md20   /backup              (4x 1TB raid 5)
/dev/md30   /holdingdisk       (1x 500GB holding disk)

Why shouldn't it be OK? I mean, you are using softraid, so I guess you don't have a big server/network.

I would recommend having hardware raid. Get a 3Ware 9550SXU-8LP Sata Controller (here it costs 285,- Euro without tax), at least 4 Sata Disks, create a Raid5+Hotspare and put /backup and /holdingdisk on it. It's a cheap solution with redundancy and hardware raid.

5. When amanda finishes writing to the holding disk, does it stop all reads from all clients (including possibly itself), until it is finished writing to /backup, before resuming reading/writing to /holdingdisk?

You can configure amanda to run multiple backups in parallel (check out the inparallel parameter) and how many dumper processes max. run at the same time on each server (maxdumps parameter). Amanda read the data from the clients to the holdingdisk and from there at the same time writes data to the final (v)tape. Depending on the dumporder parameter, amanda decides which DLE is the next. So maybe sometimes a server is idle for some time, if all dumpers are busy at the moment.

--
Snorre Stamnes
Assistant System Architect
SRCIT@Stevens
srcit AT stevens DOT edu