Avoiding disk access

Avoiding disk access

Post by Sean Hamilto » Sun, 23 Jun 2002 19:02:46



Greetings,

I have a file server with a number of noisy drives. It sits idle most of the
day, so I set the BIOS to turn off the drives after a few minutes. This
works pretty well, except sometimes they will randomly spin up, or worse,
stay on for hours.

# ps -ax
  PID  TT  STAT      TIME COMMAND
    0  ??  DLs    0:00.00  (swapper)
    1  ??  ILs    0:00.01 /sbin/init --
    2  ??  DL     0:00.01  (pagedaemon)
    3  ??  DL     0:00.00  (vmdaemon)
    4  ??  DL     0:00.03  (bufdaemon)
    5  ??  DL     0:02.17  (syncer)
    6  ??  DL     0:00.03  (vnlru)
   71  ??  Is     0:01.28 /usr/sbin/sshd

  172  p0  Ss     0:00.09 -csh (csh)
  180  p0  R+     0:00.00 ps -ax
#

If I log out, as I typically am, I imagine it looks something more along the
lines of

# ps -ax
  PID  TT  STAT      TIME COMMAND
    0  ??  DLs    0:00.00  (swapper)
    1  ??  ILs    0:00.01 /sbin/init --
    2  ??  DL     0:00.01  (pagedaemon)
    3  ??  DL     0:00.00  (vmdaemon)
    4  ??  DL     0:00.03  (bufdaemon)
    5  ??  DL     0:02.17  (syncer)
    6  ??  DL     0:00.03  (vnlru)
   71  ??  Is     0:01.28 /usr/sbin/sshd
#

What might be causing this? I've completely disabled the swap partition, am
I likely to benefit from this, or does FreeBSD not touch swap unless it
absolutely needs to?

thanks,

sh

 
 
 

Avoiding disk access

Post by <poohb.. » Sun, 23 Jun 2002 19:15:21



> Greetings,

> I have a file server with a number of noisy drives. It sits idle most of
the
> day, so I set the BIOS to turn off the drives after a few minutes. This
> works pretty well, except sometimes they will randomly spin up, or worse,
> stay on for hours.

> # ps -ax
>   PID  TT  STAT      TIME COMMAND
>     0  ??  DLs    0:00.00  (swapper)
>     1  ??  ILs    0:00.01 /sbin/init --
>     2  ??  DL     0:00.01  (pagedaemon)
>     3  ??  DL     0:00.00  (vmdaemon)
>     4  ??  DL     0:00.03  (bufdaemon)
>     5  ??  DL     0:02.17  (syncer)
>     6  ??  DL     0:00.03  (vnlru)
>    71  ??  Is     0:01.28 /usr/sbin/sshd

>   172  p0  Ss     0:00.09 -csh (csh)
>   180  p0  R+     0:00.00 ps -ax
> #

> If I log out, as I typically am, I imagine it looks something more along
the
> lines of

> # ps -ax
>   PID  TT  STAT      TIME COMMAND
>     0  ??  DLs    0:00.00  (swapper)
>     1  ??  ILs    0:00.01 /sbin/init --
>     2  ??  DL     0:00.01  (pagedaemon)
>     3  ??  DL     0:00.00  (vmdaemon)
>     4  ??  DL     0:00.03  (bufdaemon)
>     5  ??  DL     0:02.17  (syncer)
>     6  ??  DL     0:00.03  (vnlru)
>    71  ??  Is     0:01.28 /usr/sbin/sshd
> #

> What might be causing this? I've completely disabled the swap partition,
am
> I likely to benefit from this, or does FreeBSD not touch swap unless it
> absolutely needs to?

> thanks,

> sh

I suppose I can't say for sure, expect what I have experienced. With a gig
and a half of RAM my machine does not touch the 2GB SWAP partition. It may
have been overkill at the beginning but precautions are important to me. :)

Top output:
Mem: 60M Active, 1020M Inact, 117M Wired, 55M Cache, 137M Buf, 2000K Free
Swap: 2048M Total, 2048M Free

 
 
 

Avoiding disk access

Post by Sven Hazejage » Mon, 24 Jun 2002 16:36:51



> I have a file server with a number of noisy drives. It sits idle most of the
> day, so I set the BIOS to turn off the drives after a few minutes. This
> works pretty well, except sometimes they will randomly spin up, or worse,
> stay on for hours.
> What might be causing this? I've completely disabled the swap partition, am
> I likely to benefit from this, or does FreeBSD not touch swap unless it
> absolutely needs to?

Check /etc/crontab, esp. the atrun line. You might want to comment that
one out if you're not using at anyway.

Good luck!

Sven

 
 
 

Avoiding disk access

Post by Dan Fost » Mon, 12 Aug 2002 12:49:20




>I have a file server with a number of noisy drives. It sits idle most of the
>day, so I set the BIOS to turn off the drives after a few minutes. This
>works pretty well, except sometimes they will randomly spin up, or worse,
>stay on for hours.

Play detective:

        a) note day of week and time of each occurence, for about two weeks
        b) enable process accounting
        c) find out if anything started around the time of each occurence
           via process accounting

My offhand guess is that for the 'long time' stuff, may be a daily job
like updatedb or something that involves hitting the disk a lot such as
find / or equivalent.

That's only a guess, though. Process accounting will probably help nail the
culprit. Cron or at jobs are typically things that will result in some
disk activity at different times of the day. Also, file server hints that
end user activity may trigger file I/O such as FTP'ing to/from it, or
accessing a NFS/AFS/DFS/SMB volume or whatever cause I/O on the file server.
But, process accounting to the rescue. ;)

-Dan

(email sent to original poster as a courtesy and posted to USENET.)

 
 
 

Avoiding disk access

Post by Bill Vermilli » Mon, 12 Aug 2002 23:27:23






>>I have a file server with a number of noisy drives. It sits idle most of the
>>day, so I set the BIOS to turn off the drives after a few minutes. This
>>works pretty well, except sometimes they will randomly spin up, or worse,
>>stay on for hours.
>Play detective:
>    a) note day of week and time of each occurence, for about two weeks
>    b) enable process accounting
>    c) find out if anything started around the time of each occurence
>       via process accounting

Well if it's the root drive it will be updating regulary.  The
other drives may remain quiescent - but I don't know if the
automatic processes affect them or only the boot drive.  I remember
tuning the sync processes in older machines a long time ago to
wring a bit more performance out of them by cutting down the time
from every 10 seconds to every 15-20 seconds.

Bill

--

 
 
 

Avoiding disk access

Post by Igor Sobrad » Fri, 16 Aug 2002 18:15:47



> I have a file server with a number of noisy drives. It sits idle most of the
> day, so I set the BIOS to turn off the drives after a few minutes. This
> works pretty well, except sometimes they will randomly spin up, or worse,
> stay on for hours.

I have the same problem (a noisy disk) on my laptop.  Worst of all is
that I need to use it in places like libraries.

I doubt that a like in the crontab will explain it.  The disk spin up
if I change something on a file using vi too (of course, without saving
the changes to disk!) or five to ten seconds after doing an "ls -l".
In both cases, there is a small delay between the action and the disk
spin up.

I am very interested in a fix for this problem too.  It does not happens,
for example, with Solaris.

Igor.

--

 
 
 

Avoiding disk access

Post by Frank Shu » Mon, 26 Aug 2002 18:22:48




>> I have a file server with a number of noisy drives. It sits idle most of the
>> day, so I set the BIOS to turn off the drives after a few minutes. This
>> works pretty well, except sometimes they will randomly spin up, or worse,
>> stay on for hours.

> I have the same problem (a noisy disk) on my laptop.  Worst of all is
> that I need to use it in places like libraries.

> I doubt that a like in the crontab will explain it.  The disk spin up
> if I change something on a file using vi too (of course, without saving
> the changes to disk!) or five to ten seconds after doing an "ls -l".
> In both cases, there is a small delay between the action and the disk
> spin up.

> I am very interested in a fix for this problem too.  It does not happens,
> for example, with Solaris.

I don't know how vanilla vi works but vim uses a swap file which it
writes to during editing. In vim you can turn it off using the -n
option when invoking vim which should stop it writing to disk unless
asked to.

I don't know about ls accessing the disk 5-10 secs after being
run....weird!

--

 Frank

*-*-*-*-*-*-*-*-*-*-*
   Boroughbridge.
     ---------
PGP keyID: 0xC0B341A3
*-*-*-*-*-*-*-*-*-*-*

 
 
 

1. avoid disk access

Hello!

I use linux machine to play mp3's at home.

The machine has 2 HDD's. On the 1st HDD Linux is installed. There are mp3's on
2nd.

While playing 1st HDD has no work and spins down (configured with hdparm).

But when I change volume 1st HDD wakes up. The same thing happens when I go to
the next mp3 file.

When changing volume my mp3 player calls open("/dev/mixer",...)
When changing file it does open("/mnt/hdd2/music/bla-bla.mp3")
(checked with strace)

I'm looking for the way to completely (or almost completely) avoid 1st HDD
access.

I'd really appreciate it if someone could help.

--
Best wishes,    Anton Osennikov.

ps mp3 player is irmp3 (which uses mpg123 to play).

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