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Old 01-14-2004, 03:20 AM   #1
MarkBurke
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flux capacitor, why swap is not being used


Am a newbie. Help! a question I've been working on, I trying to figure out why swap is not being used on the Mandrake 9.2 machine below.

(A popular database software is reporting that shared memory cannot be created, because 330meg of memory cannot be allocated.)

Have run ls / -lR and let the memory fill up, eventually got to the result of the free command below.

uname -a reports the following

Linux cxhome 2.4.22-21mdkcustom #1 Mon Jan 5 21:12:02 PST 2004 i686 unknown unknown GNU/Linux

Other command out is as follows:


[root@cxhome dbserver]# swapon /dev/hda5
[root@cxhome dbserver]# swapon -s
Filename Type Size Used Priority
/dev/ide/host0/bus0/target0/lun0/part5 partition 130748 0 1
[root@cxhome dbserver]# ls / -lR > /dev/null 2>&1 &
[root@cxhome dbserver]# free
total used free shared buffers cached
Mem: 515136 510112 5024 0 80092 160940
-/+ buffers/cache: 269080 246056
Swap: 130748 0 130748
[root@cxhome dbserver]# cat /etc/fstab
/dev/hda1 / ext3 defaults 1 1
none /mnt/cdrom supermount dev=/dev/scd0,fs=udf:iso9660,ro,--,iocharset=iso8859-1 0 0
none /mnt/floppy supermount dev=/dev/fd0,fs=ext2:vfat,--,umask=0,iocharset=iso8859-1,codepage=850,sync 0 0
/dev/sda1 /mnt/win_c2 vfat noauto,umask=0,iocharset=iso8859-1,codepage=850 0 0
none /proc proc defaults 0 0
/dev/hda5 swap swap defaults 0 0
[root@cxhome dbserver]#
 
Old 01-14-2004, 10:41 AM   #2
jailbait
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"A popular database software is reporting that shared memory cannot be created, because 330meg of memory cannot be allocated."

I am not sure but I think that you need to make your swap partition larger. I think that both memory and swap are full and your applicaion still needs more memory.

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Old 01-17-2004, 02:45 PM   #3
MarkBurke
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I've considered putting more swap. Actually the total swap currently is a combination of my original swap (2xmem) and an additional file of swap (1gig)

The system guard program shows that swap is never being used during the time of the install, or the boot of the database software. The "free" command posted in the original command shows that the swap used at that time is zero. swap is continually zero, and is zero presently on the same computer.

I think zero swap is normal usually, until heavy memory usage, in that swap would only be used if determined if needed (i.e. more efficient regular memory is all full.) However during the error message, I see that swap is not used significantly, but I get the error message below (the one I'm trying to determine why it occurred and is block the db server from starting) during the database startup (in the log file):
os_create_region: can't allocate 37445632 bytes

The current normal memory used before the install, plus the number above, is greater than the regular memory. But no swap was attempted. During the time of the error message, swap was zero.

I've read up on swapon (man), and the swapon -s currently states the following:


Filename Type Size Used Priority
/dev/ide/host0/bus0/target0/lun0/part5 partition 130748 0 -1
/dev/ide/host0/bus0/target0/lun0/part3 partition 8032492 0 -2


I'm not sure why Priority is -1 and -2.

Mostly, just wondering why the error message os_create_region occurred, if I have plenty of swap. same result on the db startup.
 
Old 01-17-2004, 02:46 PM   #4
MarkBurke
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The free command in the original note

Mem: 515136 510112 5024 0 80092 160940
-/+ buffers/cache: 269080 246056
Swap: 130748 0 130748

Since mem is 510 meg of 515 meg, wouldn't the computer start swapping about that time? All I saw was it bumping up against the 515meg limit, and then freeing up about 5 meg, and approaching the limit again. kept doing this.
 
Old 01-17-2004, 03:08 PM   #5
jailbait
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" All I saw was it bumping up against the 515meg limit, and then freeing up about 5 meg, and approaching the limit again. kept doing this."

Yes. I think that your computer is acing like it is looking for more memory and it cannot find it in either RAM or swap.

"However during the error message, I see that swap is not used significantly"

Maybe the error occurs because even though you have set up a lot of swap space there is some logic error to where only a small portion of your swap space is being used. Are you sure that the swap file is being recognized as being part of swap space? I don't know whether the kernel swap logic can accomodate a mixture of partition swap space and file swap space. Also file swap is slower than partition swapping. I suggest that you rearrange things so that you have a large swap partition and no swap file. That may solve the problem either by fixing the swap logic or speeding up swap.

___________________________________
Be prepared. Create a LifeBoat CD.
http://users.rcn.com/srstites/LifeBo...home.page.html

Steve Stites
 
  


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