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selig
Guru
Joined: 31 Jul 2005
Posts: 425
Location: Prague, Czech Republic
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 Posted: Sun Feb 25, 2007 3:00 pm Post subject: Obscure disk activity [SOLVED] |
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Greetings,
I am trying to persuade hda to spin down... but I am unsuccessful. My setup:
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/dev/md/0 on / type ext3 (rw,noatime,commit=600)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec)
udev on /dev type tmpfs (rw,nosuid)
devpts on /dev/pts type devpts (rw,nosuid,noexec)
/dev/hdc7 on /home type ext3 (rw,noatime)
/dev/hda3 on /opt type ext3 (rw,noatime,commit=600)
none on /dev/shm type tmpfs (rw,mode=777,size=128m)
temp on /tmp type tmpfs (rw,mode=1777,size=256m,nr_inodes=8k)
kompajl on /var/tmp type tmpfs (rw,mode=1777,size=1152m,nr_inodes=128k)
usbfs on /proc/bus/usb type usbfs (rw,noexec,nosuid,devmode=0664,devgid=85)
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I have got 2GB of RAM, swap is on /dev/hdc6. md/0 is made of hda2 and hdc5.
The problem is, that when using lm-profiler, it does not show any process accessing the disk - however, when I look at the output of dstat, I can see that on hda there is a 4096B read every about 30 seconds, even when there is no write activity. What is this?  I have absolutely no idea how to prevent this. Maybe there is some setting in /proc or somewhere that could help me? Thank you for any suggestions!
Last edited by selig on Sun Mar 04, 2007 11:58 am; edited 1 time in total |
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Janne Pikkarainen
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Joined: 29 Jul 2003
Posts: 1143
Location: Helsinki, Finland
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| Posted: Sun Feb 25, 2007 6:50 pm Post subject: |
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Have you tried to enable laptop_mode? It instructs the kernel delay disk access if possible.
You might want to try it with echo 1 >/proc/sys/vm/laptop_mode and if it works, a permanent change is possible if you put line
to /etc/sysctl.conf.
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selig
Guru
Joined: 31 Jul 2005
Posts: 425
Location: Prague, Czech Republic
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| Posted: Thu Mar 01, 2007 9:54 am Post subject: |
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| Thank you for the suggestion, I will try this and post the results. The truth is that I have also tried using the laptop-mode-tools and after configuring them and starting, the disks seemed to be getting more activity than before. I will try setting this manually and see if it helps. |
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selig
Guru
Joined: 31 Jul 2005
Posts: 425
Location: Prague, Czech Republic
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| Posted: Thu Mar 01, 2007 6:46 pm Post subject: |
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I have tried setting the laptop_mode manually to 1 - it did reduce the writes to disk further, but the 4096B read still persists. Now the only thing that comes to my mind is kernel checking if hda is all right since it is a part of a RAID (md) array. On the other hand, since this is RAID-0, checking whether the disk is or is not online is rather pointless, since the system would crash anyway. But I do not believe that I can change the kernel code to get rid of this myself.  |
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KH
n00b
Joined: 28 Jun 2003
Posts: 26
Location: Canada
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| Posted: Sat Mar 03, 2007 1:41 am Post subject: |
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A good bet it's the HD temperature being read, or a SMART test being run.
If you want it to spin down, put your spindown time less than your SMART test/log time, and set the smartd daemon to not wake the drive out of sleep in the /etc/smartd.conf or /etc/conf.d/smartd files. |
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selig
Guru
Joined: 31 Jul 2005
Posts: 425
Location: Prague, Czech Republic
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| Posted: Sat Mar 03, 2007 9:37 pm Post subject: |
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| Thank you very much, it really was smartd! I tried stopping it and then the disk could spin down. I did not think of this before, I thought that smartd only queries the electronics on the drive and does no reads from the disk itself. I will change the polling interval in the config and it should be all right now. |
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Hypnos
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Joined: 18 Jul 2002
Posts: 2889
Location: Omnipresent
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| Posted: Sat Mar 03, 2007 11:14 pm Post subject: |
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The package "laptop-mode-tools" contains a tool called "lm-profiler" that reports all disk activity (file, active process) over a specified time interval.
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selig
Guru
Joined: 31 Jul 2005
Posts: 425
Location: Prague, Czech Republic
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| Posted: Sun Mar 04, 2007 11:57 am Post subject: |
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| I know... but the lm-profiler did not show smartd for some reason. It was not showing anything accessing the disk but smartd obviously was. I wonder how that is possible though. |
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Hypnos
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Location: Omnipresent
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| Posted: Sun Mar 04, 2007 12:05 pm Post subject: |
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The lm-profiler reports all activity from the Linux kernel's VFS layer. Perhaps smartd is at a lower level.
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