Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Wed, 16 Jul 2008, Lars Marowsky-Bree wrote: > On 2008-07-10T14:46:43, Stefan Novak <stefan.novak at bnet.at> wrote: > >> Hello! >> >> I test the I/O Performance using dm and bonnie. I am confused that the >> drbd Performance is only the half than directly on the /dev/sda device. >> For testing purposes I've only one single node because i want to test >> the I/O of the SCSI Controller, not of DRBD. > > You're being hit by the internal metadata. Putting the metadata on > another spindle will make it quite fast. What is the metadata overhead in DRBD? I am seeing about 100 MB/s overhead with DRBD: [root at xen1 /]# sync ; dd if=/dev/drbd0 of=/dev/null bs=4096 count=1M 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB) copied, 14.6703 seconds, 293 MB/s [root at xen1 /]# sync ; dd if=/dev/sdb of=/dev/null bs=4096 count=1M 1048576+0 records in 1048576+0 records out 4294967296 bytes (4.3 GB) copied, 10.4422 seconds, 411 MB/s ><> Nathan Stratton CTO, BlinkMind, Inc. nathan at robotics.net nathan at blinkmind.com http://www.robotics.net http://www.blinkmind.com