On Wed, Oct 09, 2002 at 09:20:44PM -0500, Craig Hancock [EMAIL PROTECTED] wrote: > > "tapes in my library are not full" is not a useful thing to say about > > amanda; amanda over-writes each tape, *never* appends. > > > > This message was from a previous message sent by Jay. > > I understand that amanda doesn't do appends of backups. > However I wasn't aware that a complete backup get overwritten. > The reason I ask this is because I thought that during backup > you have a brand new tape. If your first full backup excceds the > capcity of the tape amanda will report the area and amanda will > rewind the tape to the begining of the tape. > > So say if you have a tape with a few backups on it if the next backup exceeds > the capcity of the tape then is the statement above saying that once preexisting > backup reaches the end of the tape then will amanda rewind the tape and write over > the old backups? > > If this is the case how can this be changed
I am at a total lose as to where you are in understanding tape usage. Let me try a few statements and see where they lead you. A single tape will never hold more than one amdump run at a time. (I'm ignoring amflush situations for now) A single amdump run if larger than a single tape can be placed on multiple tapes if the runtapes parameter is > 1. Once it tries to use a tape, amanda will not attempt to reuse that tape until it uses tapecycle minus 1 more tapes, i.e. will not reuse a tape until it has gone through an entire tapecycle of tapes. When a tape is reused, it is completely overwritten, from the beginning of the tape, destroying whatever was on the tape. In another posting you asked about why it is recommended that tapecycle be at least 2x runspercycle. The problem is the possible overwriting of your only level 0 dump of a file system, or a bad dump of your only level 0. Considering a minimal situation, only 1 tape, doing full backups each night. Since todays dump overwrites your only dump, if a problem occurs, you have zero, zilch, nada backups on tape. The same thing could happen if your dumpcycle >= tapecycle. Your only level 0's could be overwritten with a bad dump and you would have nothing. Incrementals are not useful without the level 0 they are increments from. -- Jon H. LaBadie [EMAIL PROTECTED] JG Computing 4455 Province Line Road (609) 252-0159 Princeton, NJ 08540-4322 (609) 683-7220 (fax)
