[DRBD-user] Snapshot with DRBD

drbd at bobich.net drbd at bobich.net
Thu Feb 14 12:42:19 CET 2008

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On Thu, 14 Feb 2008, Leroy van Logchem wrote:

>> Here, it tells LVM2 can be used for creating snapshots.
>
> Caution: LVM2 snapshots become very slow if the amount of changes increases 
> due copy-on-write. Add the additional seeks and you have a much lower write 
> speed left.
> The last time I tried it reduced the write speed to 15% of the normal 
> throughput.

Indeed, and the more snapshots you have, the worse it gets, because the 
overwritten data has to be copied to each of the snapshots, since they 
are just sparse undo logs.

Gordan



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