On Thu, Nov 2, 2017 at 5:48 PM, 陶冬冬 <tdd21151186@xxxxxxxxx> wrote: > 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? > when handling caps flush for multiple client, mds never set mtime of inode back to an old time > 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
