[DRBD-user] what does drbd do with fsync?

Nicolas Bouthors nbouthors at nbi.fr
Wed Dec 6 15:25:51 CET 2006

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

Le 06/12/2006 08:49, Joe Buehler écrivait  :
> I am using 0.7.21 with protocol C, if it matters.

Correct me if I'm wrong but I believe that the whole point of protocol C
is to wait to the IO on the secondary node to be complete before
returning success or failure to the local ap calling fsync (or any other
file operation for that matters).

Therefore YES, it may take longer than IO on a "normal disk". If you
want to avoid this, use protocol A, where DRBD will return success or
failure to the app when the LOCAL IO is finished (performances will be
very close to what you have on a single disk).

Happy DRBDing,

  Nicolas BOUTHORS

Nicolas Bouthors -=- Tel : 06 20 71 62 34 -=- Fax : 01 46 87 21 99
NBi SARL -=- http://nbi.fr -=- nbouthors at nbi.fr

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