On Wed, Jan 03, 2018 at 01:08:37PM -0800, Chris Miller wrote: > Hi Winston, > > | I highly suggest a read of this FAQ: [ > | > http://wiki.zmanda.com/index.php/FAQ:How_are_backup_levels_defined_and_how_does_Amanda_use_them%3F > | ] ; particularly the section about Amanda's planning strategy. If you > "insist" > | on constraining Amanda to one-volume-per-backup, you are basically going > | against the strategy; without that capability, I don't think that Amanda's > | overhead gives you anything you can't do with tar and a cron job. > > I understand how Amanda wants to try to "smooth" the mix of backup > levels and filesystem sizes so that backup costs about the same amount > of time and storage each cycle, and that is a very worthwhile goal, > so I don't want to impede that. I also understand that tape discipline > is already built-in to Amanda at a fundamental level, so I don't want > to mess with that, either. So, I seek advice. > > Suppose "amanda.example.com" is backing-up "client.example.com" to > "NAS0.example.com". My level 0 backups are typically 120GB and my level 1 > backups are typically 5GB, and I have 2TB on NAS0. That's 120+6*5 = > 150GB/week, > meaning I have sufficient room for thirteen weeks of backup. This seems to me > like it might be a pretty common scenario and that there might be example > configs floating around that would size the vtapes for optimal use. Is there > one?
I'm not sure you do understand amanda's approach Chris. Amanda does not try to smooth things across a dump cycle, but across each run within a dump cycle. If your dumpcycle is 7 days with daily amdump runs, amanda's goal would be 5GB incrementals plus 120GB/7 (about 18GB) for a daily dump of about 23GB. That ideal might be achievable if you had about 14 DLE averaging about 5GB each. Then amanda could decide which 1,2,3, or 4 DLEs to do level 0 dumps each run. But in real life you have some small and some large DLEs and amanda can't meet that ideal. Assuming you have at least a few DLEs in those 120GB, some days might have a 60GB level 0 DLE to dump, other days maybe a 5 and a 10 GB, and still others maybe none and you will only have incrementals. In such a scenario I would try to size my vtapes so the largest (60GB in my example) would fit comfortably in about 3 tapes including a set of incrementals. So something like 25GB/vtape and tell amanda it can use up to 3 tapes per amdump run. The day that large DLE gets a full dump, 3 tapes will be used. Most other days probably only 1 tape will be needed. > I have some questions: Again, based on the questions below, you don't yet get the amanda scheme. There will not be A (as in "a single") level 0, each DLE will get its own schedule of level 0's. Amanda is nothing if not flexible. You can force it to do things in a "non-amanda" way. My comments after each question are about how you might achieve the goal, but then why use amanda? . > > 1. Can I make my vtapes all 150GB, and then instruct Amanda to put > one cycle (one level 0, and six level 1) on one vtape, meaning re-use a > vtape multiple time in a backup cycle? I like this approach quite a bit, > if it is possible. It "packages" one level 0 with all the attendant > level 1 differentials and eliminates my strongest reservations about > vtapes -- namely that I don't know where anything is. Amanda will not write a new amdump to the end of an existing tape containing a previous dump. I've not seen mention of a "holding disk" in this thread. If you are using one (strongly recommended) and it is sufficiently large, you could run each amdump with the option to not write to tape. The dumps will then collect on the holding disk. Then one day a week have your cronjob also do an amflush which will move all the dumps, full and incr., to one or more vtapes. You could even do your traditional all level 0's the same day if you want. Specify a dumptype of incremental only and on the day you choose specify a forced full dump. > 2. Failing that, should I make my vtapes 120GB, so I can fit a > level 0 backup on one vtape, but then will Amanda truncate level 1 backups, > so that the vtapes storage requirement is NOT 120G, but more like 5GB? You could make a 100 120GB or 150GB vtapes. They are just directories and take no space. Their size is the maximum amount of data amanda will write to a single vtape. So if only 10GB get written to each tape it those 100 tapes will only take 1/2 of your 2TB space on NAS0. Amanda will not truncate any dumps. Again assuming you are using a holding disk, any dumps that don't fit the available vtape(s) will remain on the holding disk until flushed to a vtape. This can happen automatically on the next amdump run. > 3. Alternatively, I could make my vtapes all 5GB and then Amanda will > have to span fourteen vtapes for the level 0? This might be optimal use of > storage, but it scares me with added complexity. I won't know where anything > is, meaning I will have to have Amanda tools to unpack a backup, and in the > case of a disaster, that may be really inconvenient. Hopefully you realize by now there is no "level 0". And no, you do not need amanda tools to unpack a backup. It is one of the things that attracted me to amanda. On one job I had been using a commercial backup system. During a hardware upgrade we also upgraded the backup software. After the old hardware and software was retired we found that the new version could not recover old backups. We had 2 years of unrecoverable backups. With amanda backups I just need ls, dd, tar, and gzip to recover things. This may not mollify your fear of "knowing where things are" but you get an email following each run telling you what went on. You can also have amanda send to a printer a listing of each file it created on which vtapes that run, i.e. a table of contents. But ls works also, here is a listing of my tape 13. # ls slot13 00000.DS1-013 00013.cyber.jgcomp.com.Vault-Monthly.1 00001.cyber.jgcomp.com.Photos-3.1 00014.cyber.jgcomp.com.Root.0 00002.cyber.jgcomp.com.Photos-1.1 00015.cyber.jgcomp.com.Root.0 00003.catwoman.jgcomp.com.E__Public.0 00016.mums.jgcomp.com.Root.0 00004.cyber.jgcomp.com.Photos-Misc.1 00017.mums.jgcomp.com.Root.0 00005.cyber.jgcomp.com.Photos-4.1 00018.cyber.jgcomp.com.Boot.0 00006.cyber.jgcomp.com.Photos-2.1 00019.mums.jgcomp.com.Boot.0 00007.cyberwin8.jgcomp.com.C__Users.1 00020.cyber.jgcomp.com.Var.1 00008.cyber.jgcomp.com.Home.1 00021.catwoman.jgcomp.com.C__Users.0 00009.cyber.jgcomp.com.JonMusic.1 00022.cyber.jgcomp.com.Vault-Daily.1 00010.cyber.jgcomp.com.Vault-Weekly.1 00023.cyber.jgcomp.com.Vault-Daily.1 00011.cyber.jgcomp.com.Vault-Current.1 00024.cyber.jgcomp.com.Local.0 00012.cyber.jgcomp.com.Vault-Monthly.1 00025.cyber.jgcomp.com.Opt.0 The format is: 00025. tape file number cyber.jgcomp.com. host that was backed up Opt. DLE name 0 Backup level I could peek in file 00000 to be certain when the dump was done, but probably the time stamps on the files or the directory are enough. # ls -Lld slot13 drwxr-xr-x. 2 amandabackup disk 4096 Dec 23 03:37 slot13 Tape 13 contains the backups from 2 days before Christmas. > > I sure would like to have option 1, if I could... As noted, you can. But then why use amanda? Jon -- Jon H. LaBadie j...@jgcomp.com 11226 South Shore Rd. (703) 787-0688 (H) Reston, VA 20190 (703) 935-6720 (C)
