Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
/ 2007-01-11 12:29:11 +0100 \ Ralf Schenk: > Ross S. W. Walker schrieb: > > As the subject says I want to know if it is possible to use DRBD and LVM > > snapshots to create a point-in-time replica? > > > > This would allow me to rotate snapshots in a pattern that would provide > > the best consistency/coverage for my needs. > > > > Hello ! > > I do this on a server pair with DRBD 8.0pre6 under XEN. I think you will > have to use DRBD 8.X because only later DRBD Versions claim to run > without problems on top of LVM Volumes. drbd 0.7 is also fine on top of lvm (thats our typical setup: md - lvm - drbd) or below lvm (as pv) or even (if you really want to have a headache) in some weird lower lv as storage of drbd as pv for some upper vg setup. > I snapshot the underlying LVM Volumes readonly and do rsync style > rotating Backups with the help of dirvish (http://www.dirvish.org/). you probably should snapshot them rw, so the file system is able to replay its journal. you obviously should mount them ro, of course. > To have consistent backups of my MySQL Databases I have a small perl-skript > that runs before the backup which commits a "FLUSH TABLES WITH READ > LOCK" to the MySQL Database. After the skript has taken the LVM Snapshot > via "system" calls I do "UNLOCK TABLES" so the tables are unlocked. right. so you know that at least the the mysql tables are consistent in the snapshot. > Usually this takes about 1-3 seconds and sessions that attempt to write > to MySQL wait longer for response so that only a short lock can be detected. -- : Lars Ellenberg Tel +43-1-8178292-0 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Vivenotgasse 48, A-1120 Vienna/Europe http://www.linbit.com : __ please use the "List-Reply" function of your email client.