On Fri, Jan 10, 2014 at 1:28 AM, Gregory Farnum <greg@xxxxxxxxxxx> wrote: > > 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. Yes, it depends on backend. For example, FileStore can write a object with sync to sure consistent. If adding a disable FileJournal option, we need some works on FileStore to implement it. > -Greg > Software Engineer #42 @ http://inktank.com | http://ceph.com > > > On Thu, Jan 9, 2014 at 12:13 AM, Haomai Wang <haomaiwang@xxxxxxxxx> 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 majordomo@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Best Regards, Wheat -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
