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View Full Version : dumpcycle, runspercycle, tapecycle interactions in moderate backup installation?



Andrew Rakowski
March 20th, 2007, 03:13 PM
Hi folks, I'm running Amanda-2.5.1p3 on a 4 CPU Linux system with 4GB of RAM and a couple of RAID-5 storage arrays with about 7.2TB of space split into four 1.8TB ext3 filesystems. I'm backing up 473 DLEs across 190 systems at the moment (not counting intermittent downed systems, etc.)

I'm still confused about the various interactions of the dumpcycle, runspercycle, and tapecycle settings in then amanda.conf file. My current settings for these parameters are:

....
[amandabackup@amanda01 XXXXset1]$ egrep dumpcyc\|runspercyc\|tapecyc amanda.conf
dumpcycle 4 weeks # the # of days in normal dump cycle (fulls this often at least)
runspercycle 0 # the number of amdump runs in dumpcycle days
tapecycle 80 tapes # the number of tapes in rotation
[amandabackup@amanda01 XXXXset1]$
....

I actually have 120 virtual tapes (~48GB in size) defined in the "changer.conf" file, with the settings in that file being:

....
[amandabackup@amanda01 XXXXset1]$ egrep -v file:\|eject changer.conf
gravity 0
statefile /etc/amanda/XXXXset1/changerstatus
firstslot 1
lastslot 120
[amandabackup@amanda01 XXXXset1]$
....

What I want to know is if I should make that "tapecycle 80 tapes" into a "tapecycle 120 tapes" or not.

I was under the impression that by setting the tapecycle less than the total number of tapes, I might have a "buffer" of spare tapes where I will have the ability to hold some of the old tapes. For instance, I would be able to keep around ("amadmin ... no-reuse" an old level-0 on a tape when a system is down for repair and its next "time for a level 0" time approaches (every 28 days).

Does that make any sense, or should I just make tapecycle in amanda.conf and "lastslot" in changer.conf match and call it good?

Given that I've been working this way for over a month, is there any downside of suddenly changing the tapecycle setting in amanda.conf (perhaps running out of tapes if I manage to fill them all in less than tapecycle days of backups...I'm currently running 3 to 5 tapes per day...obviously aiming for an average of 4 or less to avoid that situation.) I could see definite downsides of lowering the tapecycle value (backups all of a sudden "expiring").

Thanks for any advice you might have for me...

-Andrew