On Thursday 28 November 2002 19:22, Joffer wrote: >I just got 7 tapes and an old scsi tape streamer from a friend. I > will be installing Amanda and was thinking I would use the > following backup scheme. > >The 7 tapes are "devided" into: >2 Tapes OFF-Site >4 tapes = 4 weeks , mon-sat = incred, sun = full dump >1 - backup tape just in case > >The backup-scheme would be like this. > >First I run a full backup using the 1st of 2 OFF-SIte tapes. I > think I should create a second config for manuel archiving, > wouldn't that be the best solution? > >Then, I'd let the backupcycle begin: >1st of 4 Cycle tapes: Midnight each Monday to saturday - >changed/new files only Midnight Sunday - Full backup - >Eject backup - insert 2nd of 4 Cycle tapes > >2nd of 4 Cycle tapes: same schedule as 1st tape of course. > >3... same as 2nd etc >4.... etc >1..... etc >2...... etc > >and when my schedule or my instincts tell me it's time for a new > full off-site backup I do a manual full backup on 2nd of 2 > OFF-Site tapes while my normal cycle goes as normal (if I > remember to insert the cycle tape again after I've done a manual > one :) > >Since I've never used a tape streamer before and not very much > into the backup-scheme, I'm asking for comments on my > backup-scheme. I'de also very much like to get input on how to > achieve this.. can't say I understand the runspercycle and > typecycles etc just yet..
Hoo boy, here we go again, somebody wants to mold amanda to their way of thinking. :-) Note the smiley please as you read on. I think your last paragraph is maybe the most accurate. You're going to have 4 problems I'd suspect. 1. That drive isn't big enough to backup anything much more complex than a floppy based firewall. You've got 90 meter tapes which will hold 1 gig (uncompressed) on a really really good day. How big did you say your hard drive was? 2. That drive, if it has any real use on it, probably has a headwheel thats on its last legs, with an accompanying high error rate. I hate to toss water on your fire, but those drives go for less than a 5 dollar bill on ebay when they do sell, and I suspect many of them cost the seller the sales fee and still go unsold. With proper use of the cleaning tape, it may go for 2500-3000 running hours, and that can pile up in a couple of years if its been doing anything like a daily backup of what must have been a pretty small system. ISTR its data rate isn't more than 200kb a second, pretty slow in todays world. 3. You want to bend amanda to run things your way, and thats quite difficult for a newbie. Amanda's philosophy is to take what you give her, and do the maximum she can with it. That means amanda will want to be run every night, but its amanda who will decide the scheduleing, and amanda attempts to spread the backups out and adjust things on a day to day basis that will in time result in each nightly backup using about the same average amount of tape. To that end you have 4 variables to control the outsides of the envelope amanda can use. 1st is the tapetype defined size of the tape, in your case maybe 950 megs uncompressed. Turning any hardware compression the drive has off is the general recommendation because with it on, amanda can't get a clear view of how big the drive is and you have to fudge that value, sometimes a lot depending on the compressability of the data you backup, an unknown. Besides, a software compressor can usually do a better job, sometimes by amazing ratios. Amanda will develop a history of how each disklist entry compresses, and can after a few runs, have a very good idea of how much raw data she can put thru the compressor (usually gzip) and still make it fit the tape. 2nd is the 'dumpcycle' in amanda.conf. This defines to amanda how many realtime days she has to fit all the stuff you want backed up into the schedule. 3rd is the 'runspercycle' in amanda.conf. This tells amanda how many runs she actually has in the time defined by dumpcycle to do her job. 4th is the 'tapecycle' defined in amanda.conf. This tells amanda how many tapes she has to use, and indirectly how quick she can re-use a given tape. Now, to give you an idea, and I'm just a 2 machine home network guy who doesn't backup the second machine directly, but maintains on this machine, a set of rsync'd 'important' directorys that are backed up. Thats a total of about 150 gigs worth of drives, none of which is even remotely close to half full after my last re-arrangement. My drive is a changer, a 4 tape changer that I leave a cleaning tape in the bottom of the magazine, so it has 3 tapes available, which are DDS2's at nominally 3.85 gigs per tape uncompressed. I practically stole it on ebay about a year ago, 135 USD, brand new. I'm currently waiting for the schedule to settle a bit, having reduced dumpcycle and runspercycle from 7 days to 5 days over the last week. And I've added a few more tapes to the rotation so there are now 28 tapes in the 'tapecycle'. It shelved a full in favor of an incremental last night because the tape would have hit EOT and I haven't given it permission to 'runtapes' more than 1. So in that 5 nights running, I have the ability to fully backup 5x3.9 or about 17.5 gigs in that 5 days. With your tape stock, .95 gig x 7 tapes=6.65 gigs if all were used in the dumpcycle. However, this is not a very good arrangment because with every tape change, you will be overwriting the last good fulls of something or other. This is why I have what to you looks like way too many tapes, but if the 5,5,28 schedule actually works, I will have 5.3 full level 0 copies of everything here. If not, then I go back to 6 and 6, giving me 4.4 copies of everything on the shelf, actually a smallish solid oak pigeonhole rack I made in the shop. We have lots of oak trees here in WV, USA. :-) You need at least 2 full copies so that if one fails, you haven't destroyed your only good, but slightly older backup of that partition. This is what backing up is supposed to do, give you nearly bulletproof recovery. Also, be aware that amanda cannot, and possibly never will, have the ability to append to an already written tape, again the idea is bulletproof data security. No one knows who might eject a tape during the day and reinsert it, thereby rewinding it and destroying the location knowledge of where it is on the tape. When that happens, then the next nights incremental goes on the headend of the tape and everything beyond it on the tape from previous writes is then beyond recovery. Amanda rewinds the tape before she starts, and reads the tape ident label you put on the tape, and if its not due in the tapecycle, then amanda won't use it. However, if you have holding disk space enough, you can leave the drive empty for several days and then 'amflush' whats there to one tape provided it will fit. When using a holding disk area, be sure and leave it out of the disklist, or exclude it in amanda.conf, no use backing up what you've already backed up. Amanda can stand guard over your data like a vicious dog, but she would much rather she was allowed to do it her way. If thats not to your liking, then you should probably investigate other software, it would be easier for you in the long view. I also don't think the other software and methods will be as dependable but that one mans opinion. However, picking up a newer, bigger drive, and its tapes from ebay will no doubt ease the road ahead. Tape changers are also nice, but not a requirement. 120 meter DDS2 tapes are, when available, very reasonable, I don't think I've ever paid over 4 USD per tape when buying them in sealed tenpacks, brand new. I've NDI how that translates to Norwegian money though, sorry. Good luck! -- Cheers, Gene AMD K6-III@500mhz 320M Athlon1600XP@1400mhz 512M 99.19% setiathome rank, not too shabby for a WV hillbilly