Hi Patrick, sorry to dig out this old email. you said two clients may write same file at same time only if no any clients got “buffer/cache” capability. here my question is: the two client would got two different “mtime” of that inode, since they can make “Fw” cap dirty. how would mds behave when the two client flushes the dirty caps? Regards, Dongdong > 在 2017年7月22日，上午2:55，Patrick Donnelly <pdonnell@xxxxxxxxxx> 写道： > > Hi Sheng, > > Sorry I misspoke in my previous email. The clients may all have the > capability to read and write but none of them will be able to > **cache** reads/writes or **buffer** writes. They rely on synchronous > read/write with the OSDs for consistency/atomicity. > > On Fri, Jul 21, 2017 at 9:19 AM, sheng qiu <herbert1984106@xxxxxxxxx> wrote: >> so when multiple write clients or a mix of read and write clients >> accessing same file, the previous cached data of this file on all >> clients will be revoked. > > Yes. > >> And the following multi-clients' write or mixed read and write >> accessing to that file will become synchronous. > > Writes/reads are become synchronous, yes. > >> On Tue, Jul 18, 2017 at 9:41 AM, Patrick Donnelly <pdonnell@xxxxxxxxxx> wrote: >>> On Tue, Jul 18, 2017 at 9:17 AM, sheng qiu <herbert1984106@xxxxxxxxx> wrote: >>>> Hi Patrick, >>>> >>>> thanks for your quick response. >>>> just one concern, if disable direct I/O, multiple clients access same >>>> file via different mount point on different machines, will it cause >>>> data inconsistency? >>> >>> No, but you'll still effectively have synchronous I/O because only one >>> writer will have write capabilities from the MDS. >>> >>> -- >>> Patrick Donnelly > > > > -- > Patrick Donnelly > -- > 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 -- 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
