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, Jul 03, 2008 at 09:48:49PM +0200, H.D. wrote: > Eric Marin wrote: >> a quick question for the filesystems experts : I'd like to mount an >> EXT3 partition with the 'data=journal' option, for some tests. This >> partition is in use by DRBD (cluster of two nodes). > > To my knowledge there is no reason to use data=journal. It does not > provide any (safety) benefits over data=ordered. and usually, there are performance hits, as all file data has to be written twice now as well, once to the journal, and then to the final location. but occasionally, there _may_ be performance benefits from using data=journal, e.g. if you have sporadic heavily radom write access (as this would be converted to basically sequential writes to the journal, and then moved to final location once the sporadic activity has stopped), or when you have many small short-lived (spool) files, like on a busy smtp relay for the spool file system, because many of the files are deleted before they ever reach their final location, so they would again only be written once, and meta data, file data and journal updates are localised again into the same "hot" section on disk. you want to use the maximum journal size in this case, which is 400MB for ext3 iirc. but for "normal" file server or data base usage, data=journal will cause a performance hit, and no gain in reliability. -- : Lars Ellenberg http://www.linbit.com : : DRBD/HA support and consulting sales at linbit.com : : LINBIT Information Technologies GmbH Tel +43-1-8178292-0 : : Vivenotgasse 48, A-1120 Vienna/Europe Fax +43-1-8178292-82 : __ please don't Cc me, but send to list -- I'm subscribed