RE: Diferential Backup
Hi Roberto, I don't believe so. Amanda uses either the vendor supplied dump program, or GNU tar to do the backup. I know GNU tar does not do differential backup and AFAIK none of the vendor supplied dump programs will do differential backup either (I'm pretty sure for Solaris, AIX, *BSD, and Linux derivatives). -Original Message- From: Roberto Samarone Araujo (RSA) [mailto:[EMAIL PROTECTED] Sent: Wednesday, June 25, 2003 7:31 AM To: [EMAIL PROTECTED] Subject: Diferential Backup Hi, It it possible to use amanda to do diferential backups ? Are there any specific configuration ? Thanks, Roberto Samarone Araujo
RE: Diferential Backup
-Original Message- On Wed, 25 Jun 2003 at 9:51am, Ean Kingston wrote I don't believe so. Amanda uses either the vendor supplied dump program, or GNU tar to do the backup. I know GNU tar does not do differential backup and AFAIK none of the vendor supplied dump programs will do differential backup either (I'm pretty sure for Solaris, AIX, *BSD, and Linux derivatives). The terminology here is a bit confusing. If by differential you mean only the bits (not whole files, but bits, like rsync) that have changed, then no, neither tar nor dump do that. But if Roberto meant incremental (as in the files that have changed), then of course amanda does that. Just trying to clarify for the archives. Good point. Since a 'differential backup' is 'just the bits that changed' (like rsync) for other backup software I've used, I assumed that Roberto meant that. Perhaps I should have been clearer.
Re: Diferential Backup
On Wednesday 25 June 2003 07:30, Roberto Samarone Araujo (RSA) wrote: Hi, It it possible to use amanda to do diferential backups ? Are there any specific configuration ? Amanda will do differentials AFTER amanda has done a full. This is so that there is a baseline reference date established for that disklist entry. But I think you mis-understand how amanda works. Unlike the other solutions, amanda tries to use about the same amount of tape every night. And amanda will juggle the schedule about, moving the dates of things up by sometimes as much as 5 days in trying to achieve that, and given enough time in dumpcycles, will do pretty well at this balanceing act. To recap: dumpcycle: The number of days (or weeks) that amanda has to do a full backup of each disklist entry in. A lot of folks run 7 days or 1 week. runspercycle: In case you are doing a monday to friday only run schedule, this tells amanda how many times amanda will be run in the above 'dumpcycle' number of days. Businesses often set this to 5 since theres not much going on over the weekends. runtapes: If you have a tape changer, this sets the number of tapes amanda will be allowed to use per run. tapecycle: The number of tapes in the rotating pool. Amanda will use every tape in the pool until it has used them all, and will then start to recycle them on an oldest first basis. This should be not less than 2x runspercycle*runtapes plus 2 or 3 for comfort in knowing that you have in fact at least 2 generations of full, level 0 backups on everything in the disklist. You wouldn't want to ever get in the situation where you were over-writing your only full backup of something, and have a power failure while doing that entry's lavel 0 again. Here at home, I'm useing 7, 7, 1, 28 settings. DDS2 tapes are cheap, and I actually have about twice that many in stock. Amanda has had enough time to arrive at a fairly consistent tape useage of above 90% fill each night. -- Cheers, Gene AMD [EMAIL PROTECTED] 320M [EMAIL PROTECTED] 512M 99.26% setiathome rank, not too shabby for a WV hillbilly Yahoo.com attornies please note, additions to this message by Gene Heskett are: Copyright 2003 by Maurice Eugene Heskett, all rights reserved.
RE: Diferential Backup
On Wed, 25 Jun 2003 at 9:51am, Ean Kingston wrote I don't believe so. Amanda uses either the vendor supplied dump program, or GNU tar to do the backup. I know GNU tar does not do differential backup and AFAIK none of the vendor supplied dump programs will do differential backup either (I'm pretty sure for Solaris, AIX, *BSD, and Linux derivatives). The terminology here is a bit confusing. If by differential you mean only the bits (not whole files, but bits, like rsync) that have changed, then no, neither tar nor dump do that. But if Roberto meant incremental (as in the files that have changed), then of course amanda does that. Just trying to clarify for the archives. -- Joshua Baker-LePain Department of Biomedical Engineering Duke University
Re: Diferential Backup
On Wednesday 25 June 2003 10:01, Ean Kingston wrote: -Original Message- On Wed, 25 Jun 2003 at 9:51am, Ean Kingston wrote I don't believe so. Amanda uses either the vendor supplied dump program, or GNU tar to do the backup. I know GNU tar does not do differential backup and AFAIK none of the vendor supplied dump programs will do differential backup either (I'm pretty sure for Solaris, AIX, *BSD, and Linux derivatives). The terminology here is a bit confusing. If by differential you mean only the bits (not whole files, but bits, like rsync) that have changed, then no, neither tar nor dump do that. But if Roberto meant incremental (as in the files that have changed), then of course amanda does that. Just trying to clarify for the archives. Good point. Since a 'differential backup' is 'just the bits that changed' (like rsync) for other backup software I've used, I assumed that Roberto meant that. Perhaps I should have been clearer. And I sinned also in that I automaticly made the assumption that he actually meant incremental, since unlike an rsync scenario, the filesystem to do the differential against exists only on a tape some days back in the scheduleing, which for amanda, may as well be in Marrakesh or Ulan Bator. Or maybe even on the moon. The point being that its not directly accessable. My bad. -- Cheers, Gene AMD [EMAIL PROTECTED] 320M [EMAIL PROTECTED] 512M 99.26% setiathome rank, not too shabby for a WV hillbilly Yahoo.com attornies please note, additions to this message by Gene Heskett are: Copyright 2003 by Maurice Eugene Heskett, all rights reserved.
Re: Diferential Backup [What does differential backup mean]
[This is a meta-answer, because I've heard people say differential backup, but I had no darn idea what it meant, and I figure there might be others out there in the same boat!] On Wed, Jun 25, 2003 at 08:30:41AM -0300, Roberto Samarone Araujo (RSA) wrote: It it possible to use amanda to do diferential backups ? Are there any specific configuration ? AFAICT, there are two meanings to differential when you're talking about backups. 1) Databases. For databases (e.g., Oracle, SQL) you are often backing up a small number of very large files (and sometimes not files at all, but raw partitions). In this context, differential means backing up only those blocks within a large file (or raw partition) that have changed. This is obviously the realm of a special-purpose backup program, Amanda itself definitely doesn't know anything about it. 2) Windows file systems. Files on (all?) Windows file systems have an archive bit. The intent is that this bit is set when a file is modified. The intent is that a full backup clears all the archive bits. In this context: An incremental backup gets files that have changed since the full or previous incremental, and re-clears the archive bits. A differential backup gets files that have changed since the full, and leaves the archive bits alone. So this is sort of a round-about way of getting the same differences in behavior you get my controlling level in dump. Strictly speaking, Amanda doesn't know anything about this either. Since you're apparently a Windows guy, I'm guessing you mean windows differential, not database differential. Is that correct? And then the answer to your question depends on what type of file system you're backing up and what underlying backup engine (e.g., tar, dump, smbclient) you're using. -- Jay Lessert [EMAIL PROTECTED] Accelerant Networks Inc. (voice)1.503.439.3461 Beaverton OR, USA(fax)1.503.466.9472
Re: Diferential Backup [What does differential backup mean]
I'm using Linux and dump. Roberto Samarone Araujo [This is a meta-answer, because I've heard people say differential backup, but I had no darn idea what it meant, and I figure there might be others out there in the same boat!] On Wed, Jun 25, 2003 at 08:30:41AM -0300, Roberto Samarone Araujo (RSA) wrote: It it possible to use amanda to do diferential backups ? Are there any specific configuration ? AFAICT, there are two meanings to differential when you're talking about backups. 1) Databases. For databases (e.g., Oracle, SQL) you are often backing up a small number of very large files (and sometimes not files at all, but raw partitions). In this context, differential means backing up only those blocks within a large file (or raw partition) that have changed. This is obviously the realm of a special-purpose backup program, Amanda itself definitely doesn't know anything about it. 2) Windows file systems. Files on (all?) Windows file systems have an archive bit. The intent is that this bit is set when a file is modified. The intent is that a full backup clears all the archive bits. In this context: An incremental backup gets files that have changed since the full or previous incremental, and re-clears the archive bits. A differential backup gets files that have changed since the full, and leaves the archive bits alone. So this is sort of a round-about way of getting the same differences in behavior you get my controlling level in dump. Strictly speaking, Amanda doesn't know anything about this either. Since you're apparently a Windows guy, I'm guessing you mean windows differential, not database differential. Is that correct? And then the answer to your question depends on what type of file system you're backing up and what underlying backup engine (e.g., tar, dump, smbclient) you're using. -- Jay Lessert [EMAIL PROTECTED] Accelerant Networks Inc. (voice)1.503.439.3461 Beaverton OR, USA(fax)1.503.466.9472
