--On Wednesday, April 24, 2002 13:23:08 -0700 John Koenig <[EMAIL PROTECTED]> wrote:
> Can those with experience with changers elucidate some details for me? > > What is the AMANDA/amtape policy when "rolling over" from the last > tape to the first tape in my "Backup Set"? My config specifies the > following: > > dumpcycle 2 weeks > runspercycle 5 > tapecycle 10 tapes > > In my changer the slot numbering is zero-based. So I have tapes in > slots 0 thru 9. > > Since I do not have a working changer script between amtape and my > tape library manager sw layer, I am manually running robot load > commands (etc...). I have three general questions: > > 1) Will amtape manage the rollover from tape slot 9 to slot 0, and, > in general, do the right thing? Is there any manual intervention on > tape slot rollover? For example. must the admin tell AMANDA that it > is OK to write over a tape (tape "00")? Yes, it knows to roll over from the last tape to the first, but see #3 below. > 2) Is there any important information omitted from the document, > "AMANDA Tape Changer Support"? Can it generally be trusted to specify > the correct interfaces? I have found that some of the tape changer > implementations in the AMANDA distribution do not correctly follow > the API specifications in that document. I'll pass on this one. > > 3) Do people with single tape robots use multiple tape magazines; > swapping them out after one tapecycle... as in Magazine A then > Magazine B, then back to A? Or do some people just keep running > tapes through the magazine, ad infinitum? Or do most people leave > the same magazine installed until the tapes wear out? I presume > this last question (3) is largely dependent upon one's goals... > So if anybody cares to elaborate on changer methodologies used to > achieve particular goals, then I would be grateful. Other will > surely benefit as this is not an area that is discussed in much depth. You need at least a couple more tapes, since with your current setup if you ever have a tape error or an extra-large backup and need to amflush, it would need to overwrite an active tape. The other answer is, as you suspect, 'it depends'. If you do offsite rotations of your tapes, it is easier to do it a magazine at a time. If your robot holds several magazines you might want to cycle through one set for onsite backups and have a different Amanda config do offsite backups on another magazine that you replace each time. Even if you don't do offsite, swapping tapes a magazine at a time is much safer than swapping tapes. The tapes will last longer in a magazine (less likely to get banged around, dropped, dirtied, etc.), and you have fewer chances to get the tapes out of order. Magazines also stack better and are easier to store. I'm assuming your magazines can be swapped easily, if not then it might not be as favorable to swap them. Unfortunately, some vendors see magazines as an income opportunity and charge way too much for them. Also, do you need archival backups (to retrieve a file that was only around last June), or only the ability to restore what was there in the last few days or weeks. With your config, if a backup fails for some reason, and a file you need wasn't on the system in the last week, you may not have it (as you are just now about to overwrite your first tape, and whatever fulls it contains cannot be recreated with the following 4 incrementals so all you can recover from those filesytems of that week is the changed files. If the full of those filesystems can't be read from the one this week (due to a bad tape or whatever) you are SOL. I would recommend making sure you always have at least two full backups of everything, even if there are a couple of errors during your cycle. Good luck, Frank -- Frank Smith [EMAIL PROTECTED] Systems Administrator Voice: 512-374-4673 Hoover's Online Fax: 512-374-4501
