Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi, > DRBD version, LVM version, Device mapper version (kernel version), > distribution? DRBD version 8.3.10(we noticed this with 8.3.5 at first, and update DRBD after that) LVM version LVM2(included RHEL in 5.2) kernel version 2.6.18-92.EL5 (x86_64） distribution RHEL 5.2 > What about oflag=dsync instead of direct? > What about not specifying any oflag, but doing > # dd if=/dev/zero of=/mnt/dd/10GB.dat bs=1M count=10000 conv=notrunc,fsync OK, I'll try it. > What about reads? > With iflag=direct? We just felt that reads were also slow, but we didn't record them as mathematical values. > Without without iflag, but still cache cold, > after an echo 3 > /proc/sys/vm/drop_caches? yes, we went clear the drop_caches, and also did "mount/unmount" the device. > Do you have an other data point with more recent (all of it), > especially with more recent LVM + upstream kernel? We tried the same test on RHEL 5.2、5.5、6.1, but the results was the same. Thanks, Junko IKEDA