I did some measurements to check how often my nilfs2 drives are in standby during one day (24h), during this time only a daily backup script has been accessing the disks (rsync from some other directories on /dev/sda1). For comparison I have also included an ext4 partition on /dev/sdc. Note: there are no other partitions on these disks so there should basically be no activity. (I am running Ubuntu 9.10 so an occassional updatedb or similar can be expected, besides my daily backup script.) The nilfs2 settings used during measurement (where I am trying to force the drives to standby as much as possible, hence, it is not a typical use of nilfs2): protection_period = 86400 nsegments_per_clean = 20 cleaning_interval = 86400 (86400 seconds correspond to 24h) Results: nilfs2 /dev/sdb spindown 34 %, count 18, max 2340 sec, spindown time accumulated 29430 sec nilfs2 /dev/sdd spindown 47 %, count 26, max 2370 sec, spindown time accumulated 41220 sec ext4 /dev/sdc spindown 89 %, count 5, max 53580 sec, spindown time accumulated 77430 sec Same measurement, but this time with no cleanerd running for sdb and sdd; still the result is in the same range. nilfs2 /dev/sdb spindown 23 %, count 11, max 2340 sec, spindown time accumulated 20580 sec nilfs2 /dev/sdd spindown 47 %, count 23, max 2340 sec, spindown time accumulated 41190 sec ext4 /dev/sdc spindown 87 %, count 3, max 55200 sec, spindown time accumulated 75870 sec ['count' refers to the number of times the disk has been spun down, 'max' refers to the maximum time the disk has been in the spun down state] I was quite surprised to see that the nilfs2 disk where quite rarely in the spun down state, at least when compared to the ext4 disk, nilfs2 23-47% vs. ext3 ~87%. Also, stopping the cleanerd seamed to have little effect on disk spinning down. Could anyone explain what is being done to the nilfs disks during this time (or provide a reference)? I would have expected the disks to be spun down much more of the time, for example, on par with the ext4 disk (~87% spun down). What can I do to reduce disk activity on the nilfs2 partitions further? For example, should I be using other settings? Markus ps. I have set the standby timeout on these disk using hdparm; hdparm -S 30 /dev/xx. hdparm -B did not work for me. In my measurements I am checking the disks state using 'hdparm -C', each disk sampled every 30 seconds. The measurements are done using a bash script. -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
