Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On 2009-07-02 15:28, Raoul Bhatia [IPAX] wrote: > hi, > > Federico Simoncelli wrote: >> On Thu, Jul 2, 2009 at 10:39 AM, Florian Haas<florian.haas at linbit.com> wrote: >>> Federico, >>> >>> out of curiosity: does this throughput drop also occur when you activate >>> your "TestGroup00" VG in exclusive mode? >> Hi Florian, >> I did the tests again using just LVM: What do you mean, you changed back to locking_type = 1? > just for the records, i do not think that testing disk-speed with a > ~100MB file when your controller has 128MB cache is a good indicator. Nonetheless 50 MB/s write speed per disk is a reasonable expectation on current hardware, and 14.2 MB/s would be way too slow. Still, it's probably wise to rerun the test writing one big chunk that fits into memory (RAM), but not into the on-controller cache. Something like bs=1G count=1 (assuming you have more than 2G or so RAM). > moreover, the protocol in use might have a big impac there. quoting > from my commented drbd.conf > >> # C: write IO is reported as completed, if we know it has >> # reached _both_ local and remote DISK. >> # * for critical transactional data. > > *maybe* this is the issue. drbd waits for an ack from the disk subsystem > requesting the controller to write the data to the disks whereas (c)lvm > is happy as soon as the data hits the controller cache. > > of course, i might be wrong ;) You are, because the original intention was to use DRBD together with CLVM, which requires running DRBD in dual-Primary mode, which in turn necessitates protocol C. Florian -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 260 bytes Desc: OpenPGP digital signature URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20090702/0dbc113b/attachment.pgp>