Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi all I was testing the performances of CLVM over DRBD and I found that the write speed on a logical volume is quite slow (15.1 MB/s) compared to the write speed on the raw drbd0 device (47.2 MB/s). Is this a known issue or there might be something wrong in my configuration? I'm using a Smart Array E200 (128Mb BBWC with cache enabled) which normally writes at ~50MB/s. I've a plain drbd.conf configuration (the parameters: al-extents, sndbuf-size, max-buffers, max-epoch-size, unplug-watermark, no-disk-barrier, no-disk-flushes, no-md-flushes are set to the default values). The connection between the nodes is done with two BCM5722 Gigabit Ethernet (tg3) with default mtu (1500). I think my setup shouldn't be the problem since writing on the drbd device is performing quite well (47.2 MB/s). Test: # sync && dd if=/dev/zero of=/dev/drbd0 bs=1M count=100 oflag=direct 100+0 records in 100+0 records out 104857600 bytes (105 MB) copied, 2.22116 seconds, 47.2 MB/s # pvcreate /dev/drbd0 Physical volume "/dev/drbd0" successfully created # vgcreate -cy TestGroup00 /dev/drbd0 Clustered volume group "TestGroup00" successfully created # vgs VG #PV #LV #SN Attr VSize VFree TestGroup00 1 0 0 wz--nc 465.71G 465.71G VolGroup00 1 2 0 wz--n- 148.94G 0 # lvcreate -n SpeedTest00 -L 4G TestGroup00 Logical volume "SpeedTest00" created # sync && dd if=/dev/zero of=/dev/TestGroup00/SpeedTest00 bs=1M count=100 oflag=direct 100+0 records in 100+0 records out 104857600 bytes (105 MB) copied, 6.96609 seconds, 15.1 MB/s -- Federico.