I am using Debian 8.0 x64 with 72 GB of RAM with 4 drives configured as software RAID 0.
Linux s1 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt11-1 (2015-05-24) x86_64 GNU/Linux
I tried setting dirty pages to 2GB cache before actual writing. I also tried setting the "dirty_ratio" and "dirty_background_ratio" settings to use 50% of RAM but that didn't work either. The pdflush daemon should start every minute and expire time for dirty pages was set to 10 minutes.
I checked the disk I/O using "iotop" and it showed disk a high writing activity. Also "cat /proc/meminfo" showed that the "Dirty" value is getting smaller (probably due to writing). Before checking I ran "sync" and "drop_caches". I tested using the "dd" command writing a 1GB file of zeroes.
- Here are the settings:
echo 0 > /proc/sys/vm/dirty_background_ratio
echo 2147483648 > /proc/sys/vm/dirty_background_bytes
echo 0 > /proc/sys/vm/dirty_ratio
echo 2147483648 > /proc/sys/vm/dirty_bytes
echo 6000 > /proc/sys/vm/dirty_writeback_centisecs
echo 30000 > /proc/sys/vm/dirty_expire_centisecs
- Mount options:
/dev/md0 on /test type ext4 (rw,noatime,nodiratime,nobarrier,stripe=512)