The FileJournal is also for data safety whenever we're using write ahead. To disable it we need a backing store that we know can provide us consistent checkpoints (i.e., we can use parallel journaling mode — so for the FileJournal, we're using btrfs, or maybe zfs someday). But for those systems you can already configure the system not to use a journal. -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com
On Thu, Jan 9, 2014 at 12:13 AM, Haomai Wang <[email protected]> wrote: > Hi all, > > We know FileJournal plays a important role in FileStore backend, it can > hugely reduce write latency and improve small write operations. > > But in practice, there exists exceptions such as we already use FlashCache or > cachepool(although it's not ready). > > If cachepool enabled, we may use use journal in cache_pool but may > not like to use journal in base_pool. The main reason why drop journal > in base_pool is that journal take over a single physical device and waste > too much in base_pool. > > Like above, if I enable FlashCache or other cache, I'd not like to enable > journal in OSD layer. > > So is it necessary to disable journal in special(not really special) case? > > Best regards, > Wheats > > > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
