Red Hat Bugzilla – Bug 469290
Massive USB Slow Down after hours of computer use
Last modified: 2013-06-24 13:12:51 EDT
I backup to a Transcend JF110 USB thumb drive. It has a 25 MB/s write speed.
It is very fast. It backups up 940 MB in 1 minute and 32 seconds. Except
if I have been running my computer all day, in which case it takes 92 minutes.
I have been rebooting before doing my backups as a workaround. I get my speed
back after the reboot.
Programs that I run: firefox, thunderbird, gimp, open office 3, thunar, XFce,
Wine, Virtual Box 1.6.6 and 2.0.2 (Guest: XP Pro sp3: word pro, 123,
approach, Acrobat 8 pro, Go To Assist Express)
Bug has no I-T number, I'm working with the requestor out of band.
Steps to reproduce:
1) start a "dump" from my primary partition (/dev/sda1) to my removable
SATA (not eSata) backup drive (/dev/sdb2)
2) let "dump" run for about ten minutes (full dump takes 1hr 45min to run)
3) stop the "dump" with a <Ctrl><C>
After that, a 940 MB copy from /dev/sda2 to my USB stick will drop from
1 min 32 sec to 92 minutes. (Rebooting always fixes it.)
940 MB copy from /dev/sda2
It is doing it right now. I can not remember what test you wanted me to do when the symptom appears. Would you give me a list so as next time I can take some data for you?
Just got a posting over on CentOS forum:
The writer was checking out why rhel 3 and rhel 5 performed so differently on large file transfers. He found that the dirty_background_ratio and dirty_ratio were set to 50 under rhel3 and 2 and 8 respectively on rhel5. He set both rhel5's to 50 and problem solved. The is what he did:
root@ddb04>echo 50 > /proc/sys/vm/dirty_background_ratio
root@ddb04>echo 50 > /proc/sys/vm/dirty_ratio
Mine are set to:
# cat /proc/sys/vm/dirty_background_ratio
# cat /proc/sys/vm/dirty_ratio
Could this problem be solved just by changing these two values?
I can not reproduce this problem since upgrading to CentOS 5.4. Did you guys fix some USB bugs in 5.4?
Anyway, you can close this as "works in 5.4". (I tried, but it got mad at me.)
Many, many thanks,