Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Stefan Seifert-3 wrote: > > On Wednesday 14 April 2010 13:46:38 loopx wrote: > >> http://www.drbd.org/docs/introduction/ : >> Protocol C. Synchronous replication protocol. Local write operations >> on >> the primary node are considered completed only after both the local and >> the >> remote disk write have been confirmed. As a result, loss of a single node >> is guaranteed not to lead to any data loss. Data loss is, of course, >> inevitable even with this replication protocol if both nodes (or their >> storage subsystems) are irreversibly destroyed at the same time. By far, >> the most commonly used replication protocol in DRBD setups is protocol >> C. >> ------------- >> >> But, when using 8.3.2 (on both side), and copy a 10Gb (9.6 in fact) file >> from LOCAL (/) to DRBD0 (mounted under /mnt/), I see that the local copy >> is >> finished, but the network transfert is not yet finished and didn't >> receive >> the complete file (see the amount of date received by using "iftop") ... > > The solution is very simple: while drbd waits for the remote side to > complete > writing before signaling a write completed, cp itself does not wait! cp > just > issues the write request, but does not wait for it to complete. So the > missing > data is still in your local write cache waiting to be processed by drbd > and > your disks. > > You can see the same with pure local writes, although it's harder to see > because a local disk is writing quicker: cp is finished while your disk is > still working. To be sure that the write is completed, issue a sync after > your > cp or use something a bit more sophisticated for your tests like dd as has > been explained quite a few times on this list. > > Regards, > Stefan Seifert > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > > Thanks you very much for you answer and sorry about the already know "behavior". I successfully completed some test with "cp + sync" and "dd + fsync" and all is now fine when I broke the network after the command return to the shell ;-). Regards, Laurent -- View this message in context: http://old.nabble.com/Strange-replication-using-DRBD-8.3.2-tp28241563p28256672.html Sent from the DRBD - User mailing list archive at Nabble.com.