On Thu, Feb 27, 2014 at 07:19:24PM -0500, Michael Stauffer wrote: > Amanda 3.3.4 > > Hi, > > Another long post from me - thanks to anyone who has time to read it. > > I've been reading various docs and posts about dumpcycle, runspercycle, > tapecycle, runtapes online, but still can't figure out how I should set > things up for my needs. > > I've got: > - ca. 30TB of data to backup > - I'll try to split this into 500GB or 1TB DLE's, but some will be much > easier to leave as 2-4TB DLE's > - I'm fine with a level 0 only every 30 days, especially considering a full > backup will take 8-10 days. > - I've got 1.5TB tapes that hold about 2TB of data with hardware > compression from testing > - my changer holds 35 tapes
First question, will you be using more than 35 tapes. I.e. will you periodically pull some recently used and replace with less recently used tapes? If not, I think you are short on tapes. A full dump will take 15 tapes. You really want a MINIMUM of two full dumps. I prefer more. So 2x15 is two full dumps leaving only 5 tapes for incrementals. I don't think that will be enough. > I'd like to have the changer always hold a level 0 dump and then the set of > subseuqent incrementals. So it should take about 15-20 tapes for a level 0 > of all DLE's, and then the incrementals over a month should easily fit > within 2-4 tapes, judging from experience here. When the next level 0 dump > starts, I'd like amanda to use as many of the remaining 10 or so tapes > before overwriting tapes from the old level 0 dump (overwriting only tapes > of DLE's that have just had a new level 0, of course). (I will periodically > do a level 0 dump to a different tape set for offset archiving) > Do you plan to let amanda do the scheduling? Or are you going to force her kicking and screaming into the traditional schedule of one monster full dump followed by all incrementals. Then another monster. Blech. > How do I setup dumpcycle, runspercycle, tapecycle, runtapes to achieve this? > > >From the docs, it seems I'd want: > dumpcycle 30 days > runspercycle 15 #15, for running amdump every other day > runtapes 2 # to allow for DLE's that can get up to 4TB > tapecycle 34 # at least (runspercycle + 1) * runtapes - per docs > suggestion > # and leave one extra as a spare > > Is this right? > > Does this mean that when I run amdump, it will at most write two > tapes-worth of DLE's, and then stop? Then the next run will pick up from > there? I think so, but would like to make sure. I'm used to the manual > paradigm of "run a full backup" and then do incrementals. But this seems > that it will level out to be the same in the end as that? > > HOWEVER, I'd rather have runtapes at 3 or 4 to minimize tape waste and make > it less critical to have evenly-sized DLE's, which will be difficult to > maintain. But if runtapes is 3, the recommended value of tapecycle would be > >= 48, more than my # of tapes. But in practice, 35 should still plenty of > tapes to do what I want without overwriting level 0's prematurely. It seems > like tapecycle minimum should be more like '# of tapes per full backup + # > of tapes for incrementals over dumpcycle + 2 * runtapes', plus one or two > as a buffer. The following sentence shows you are still thinking the "non-amanda way. > The formula in the docs of "(runspercycle + 1) * runtapes" > plays it very safe when you consider many incremental dumps will go to > holding disk and be collected onto one tape periodically. There are not going to be a bunch of incrementls to collect onto one tape. Each amdump run will be a mix of level 0's for some DLEs and incrementals for the others. With 15 runspercycle you will AVERAGE 2TB of level 0 plus ??GB of incrementals. But remember you said some DLEs will be 4 or more TB. When they get level 0's you'll need more than 2 tapes. Jon -- Jon H. LaBadie j...@jgcomp.com 11226 South Shore Rd. (703) 787-0688 (H) Reston, VA 20190 (609) 477-8330 (C)
