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| -rw-r--r-- | doc/src/sgml/backup.sgml | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml index 01d023aae0d..789e4a11e30 100644 --- a/doc/src/sgml/backup.sgml +++ b/doc/src/sgml/backup.sgml @@ -1,5 +1,5 @@ <!-- -$PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.58 2005/03/17 05:10:11 momjian Exp $ +$PostgreSQL: pgsql/doc/src/sgml/backup.sgml,v 2.59 2005/03/17 15:38:46 momjian Exp $ --> <chapter id="backup"> <title>Backup and Restore</title> @@ -364,9 +364,11 @@ tar -cf backup.tar /usr/local/pgsql/data </para> <para> - If your database is spread across multiple volumes (for example, - if you are using tablespaces) there may not be any way - to obtain exactly-simultaneous frozen snapshots of all the volumes. + If your database is spread across multiple file systems there may not + be any way to obtain exactly-simultaneous frozen snapshots of all + the volumes. For example, if your data files and WAL log on different + file disks, or if tablespaces are on different file systems, it might + not be possible to use snapshots because the snapshots must be simultaneous. Read your file system documentation very carefully before trusting to the consistent-snapshot technique in such situations. The safest approach is to shut down the database server for long enough to @@ -375,11 +377,12 @@ tar -cf backup.tar /usr/local/pgsql/data <para> Another option is to use <application>rsync</> to perform a file - system backup. First, while the database server is running, - run <application>rsync</>, then shut down the database - server and perform a second <application>rsync</>, then - restart the database server. This allows a file system backup to be - performed with minimal downtime. + system backup. This is done by first running <application>rsync</> + while the database server is running, then shutting down the database + server just long enough to do a second <application>rsync</>. The + second <application>rsync</> will be much quicker than the first, + but will be consistent because the server was down. This method + allows a file system backup to be performed with minimal downtime. </para> <para> |