Hi, There is a sync thread (sync_entry in FileStore.cc) which triggers periodically and executes sync_filesystem() to ensure that the data is consistent. The journal entries are trimmed only after a successful sync_filesystem() call
Thanks Viju >-----Original Message----- >From: [email protected] >[mailto:[email protected]] On Behalf Of Pawel Sadowski >Sent: Tuesday, December 30, 2014 1:52 PM >To: [email protected] >Subject: Ceph data consistency >Hi, >On our Ceph cluster from time to time we have some inconsistent PGs (after >deep-scrub). We have some issues with disk/sata cables/lsi controller causing >IO errors from time to time (but that's not the point in this case). >When IO error occurs on OSD journal partition everything works as is should -> >OSD is crashed and that's ok - Ceph will handle that. >But when IO error occurs on OSD data partition during journal flush OSD >continue to work. After calling *writev* (in buffer::list::write_fd) OSD does >check return code from this call but does NOT verify if write has been >successful to disk (data are still only >in memory and there is no fsync). >That way OSD thinks that data has been stored on disk but it might be >discarded (during sync dirty page will be reclaimed and you'll see "lost page >write due to I/O error" in dmesg). >Since there is no checksumming of data I just wanted to make sure that this is >by design. Maybe there is a way to tell OSD to call fsync after write and have >data consistent? >-- >Cheers, >PS >-- 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 ________________________________ PLEASE NOTE: The information contained in this electronic mail message is intended only for the use of the designated recipient(s) named above. If the reader of this message is not the intended recipient, you are hereby notified that you have received this message in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify the sender by telephone or e-mail (as shown above) immediately and destroy any and all copies of this message in your possession (whether hard copies or electronically stored copies). N�����r��y����b�X��ǧv�^�){.n�+���z�]z���{ay� ʇڙ�,j��f���h���z� �w��� ���j:+v���w�j�m��������zZ+�����ݢj"��!�i
