Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On 06/20/2011 07:16 AM, Noah Mehl wrote: > > > On Jun 20, 2011, at 12:39 AM, Noah Mehl wrote: > >> On Jun 18, 2011, at 2:27 PM, Florian Haas wrote: >> >>> On 06/17/2011 05:04 PM, Noah Mehl wrote: >>>> Below is the script I ran to do the performance testing. I basically took the script from the user guide and removed the oflag=direct, >>> >>> ... which means that dd wrote to your page cache (read: RAM). At this >>> point, you started kidding yourself about your performance. >> >> I do have a question here: the total size of the dd write was 64GB, twice the amount of system RAM, does this still apply? >> >>> >>>> because when it was in there, it brought the performance down to 26MB/s (not really my focus here, but maybe related?). >>> >>> "Related" doesn't begin to describe it. >>> >>> Rerun the tests with oflag=direct and then repost them. >> >> Florian, >> >> I apologize for posting again without seeing your reply. I took the script directly from the user guide: >> >> #!/bin/bash >> TEST_RESOURCE=r0 >> TEST_DEVICE=$(drbdadm sh-dev $TEST_RESOURCE) >> TEST_LL_DEVICE=$(drbdadm sh-ll-dev $TEST_RESOURCE) >> drbdadm primary $TEST_RESOURCE >> for i in $(seq 5); do >> dd if=/dev/zero of=$TEST_DEVICE bs=512M count=1 oflag=direct >> done >> drbdadm down $TEST_RESOURCE >> for i in $(seq 5); do >> dd if=/dev/zero of=$TEST_LL_DEVICE bs=512M count=1 oflag=direct >> done >> >> Here are the results: >> >> 1+0 records in >> 1+0 records out >> 536870912 bytes (537 MB) copied, 0.911252 s, 589 MB/s [...] If your controller has a BBU change the write policy to writeback and disable flushes in your drbd.conf HTH -- Cristian Mammoli APRA SISTEMI srl Via Brodolini,6 Jesi (AN) tel dir. +390731719822 Web www.apra.it e-mail c.mammoli at apra.it