From 0c5fbe59244eb47b97a452f7d7a27567fc105295 Mon Sep 17 00:00:00 2001 From: Giorgos Keramidas Date: Mon, 12 Dec 2005 15:16:03 +0000 Subject: [PATCH] Add a section that describes briefly various backup strategies available with FreeBSD, their relative merits and what the final choise of a backup strategy has to cover/support. PR: docs/89900 Submitted by: Lowell Gilbert --- .../books/handbook/disks/chapter.sgml | 91 +++++++++++++++++++ 1 file changed, 91 insertions(+) diff --git a/en_US.ISO8859-1/books/handbook/disks/chapter.sgml b/en_US.ISO8859-1/books/handbook/disks/chapter.sgml index 58eed9e5ba..f2228c14f8 100644 --- a/en_US.ISO8859-1/books/handbook/disks/chapter.sgml +++ b/en_US.ISO8859-1/books/handbook/disks/chapter.sgml @@ -2270,6 +2270,97 @@ sa0(ncr1:4:0): Logical unit is in process of becoming ready + + + + + Lowell + Gilbert + Original work by + + + + + + Backup Strategies + + The first requirement in devising a backup plan is to make sure that + all of the following problems are covered: + + + + Disk failure + + + Accidental file deletion + + + Random file corruption + + + Complete machine destruction (e.g. fire), including destruction + of any on-site backups. + + + + It is perfectly possible that some systems will be best served by + having each of these problems covered by a completely different + technique. Except for strictly personal systems with very low-value + data, it is unlikely that one technique would cover all of them. + + Some of the techniques in the toolbox are: + + + + Archives of the whole system, backed up onto permanent media + offsite. This actually provides protection against all of the + possible problems listed above, but is slow and inconvenient to + restore from. You can keep copies of the backups onsite and/or + online, but there will still be inconveniences in restoring files, + especially for non-privileged users. + + + + Filesystem snapshots. This is really only helpful in the + accidental file deletion scenario, but it can be + very helpful in that case, and is quick and + easy to deal with. + + + + Copies of whole filesystems and/or disks (e.g. periodic rsync of + the whole machine). This is generally most useful in networks with + unique requirements. For general protection against disk failure, + it is usually inferior to RAID. For restoring + accidentally deleted files, it can be comparable to + UFS snapshots, but that depends on your + preferences. + + + + RAID. Minimizes or avoids downtime when a + disk fails. At the expense of having to deal with disk failures + more often (because you have more disks), albeit at a much lower + urgency. + + + + Checking fingerprints of files. The &man.mtree.8; utility is + very useful for this. Although it is not a backup technique, it + helps guarantee that you will notice when you need to resort to your + backups. This is particularly important for offline backups, and + should be checked periodically. + + + + It is quite easy to come up with even more techniques, many of them + variations on the ones listed above. Specialized requirements will + usually lead to specialized techniques (for example, backing up a live + database usually requires a method particular to the database software + as an intermediate step). The important thing is to know what dangers + you want to protect against, and how you will handle each. + + Backup Basics