SWAP space not accessed by OS

[ajitup]

Hi!

I have SuSe Linux 10.1 installed on a dual processor (Intel Xeon - No.s) server with 4GB RAM. I have put 2GB of swap space (I also tried 12GB SWAP space but the problem was same).

The swap space is shown by

system-> monitor-> memory
as well as by "free" comand. It is also there in /etc/fstab and is shown in "fdisk -l"

BUT this swap space is not acceessed by the code I am running.

e.g.

I have another system (P-IV, -1GB RAM, 2GB SWAP space) with same OS and when I run my code for a large data set, this system shows a full "Physical Memory" and then "SWAP" space is also used (upto 70%)


When I run my code with the same data-set on 4GB-RAM machine, it gives an error "insufficient memory" and exists. When run with a slightly smaller data set, it shows 74% usage of "Physical Memory" and 100% free SWAP space. BUT when I increase data-set, OS does not access swap, rater exits the program.

I have checked swap space, it is ON (swapon) and still not accessible!

Plesae provide me help on this issue !

a lot of thanks in advance

ajit,
indore

[techieMoe]

Swap space is only used when the system runs out of physical RAM. You will likely never need more than around 512MB of swap space. More is just a waste of your harddrive.

[ajitup]

Hi!

Please pay attention to the following lines and then give your suggestion ---->>

I have another system (P-IV, -1GB RAM, 2GB SWAP space) with same OS and when I run my code for a large data set, this system shows a full "Physical Memory" and then "SWAP" space is also used (upto 70%)


When I run my code with the same data-set on 4GB-RAM machine, it gives an error "insufficient memory" and exists. When run with a slightly smaller data set, it shows 74% usage of "Physical Memory" and 100% free SWAP space. BUT when I increase data-set, OS does not access swap, rater exits the program.

I have checked swap space, it is ON (swapon) and still not accessible!

Plesae provide me help on this issue !

a lot of thanks in advance

ajit,
indore

[gogalthorp]

Hi!

Please pay attention to the following lines and then give your suggestion ---->>

I have another system (P-IV, -1GB RAM, 2GB SWAP space) with same OS and when I run my code for a large data set, this system shows a full "Physical Memory" and then "SWAP" space is also used (upto 70%)


When I run my code with the same data-set on 4GB-RAM machine, it gives an error "insufficient memory" and exists. When run with a slightly smaller data set, it shows 74% usage of "Physical Memory" and 100% free SWAP space. BUT when I increase data-set, OS does not access swap, rater exits the program.

I have checked swap space, it is ON (swapon) and still not accessible!

Plesae provide me help on this issue !

a lot of thanks in advance

ajit,
indore

What processor on the new system?? Which version of SUSE??

This sounds like a problem that should be bumped up to the kernel guys.

[ajitup]

Hi!

thanks for your interest!

It has two Intel Xeon Processors - 3GHz on an Intel 7520 motherboard with 4GB - 400MHz ECC RAM. One 73 GB SCSI HDD and two 250 GB SATA. OS is installed on SCSI (i.e. root & swap or on same scsi disk).

SuSe Linux 10.1 (x86_64) is installed (I have tried with 32 bit version of SuSe 10.1 & RedHat EL4 too, but the problem is same on these OS too).

thanks again,
ajit

[pavlo_7]

what does:

cat /proc/swaps

show?

[ajitup]

what does:

cat /proc/swaps

show?

it shows:

/dev/sdc2 partition 2064344 148 -1


at present I have 2GB of swap space. "free" also gives the same swap usage profile.

ajit

[pavlo_7]

it shows:

/dev/sdc2 partition 2064344 148 -1

So it does mount the swap partition. At this point I do not know why it is not using it. Maybe someone who knows will reply. You could try to use swap file instead of swap partition
( http://www.europe.redhat.com/documen...ap-adding.php3), but I doubt it would make a difference.

[gogalthorp]

Hi!

thanks for your interest!

It has two Intel Xeon Processors - 3GHz on an Intel 7520 motherboard with 4GB - 400MHz ECC RAM. One 73 GB SCSI HDD and two 250 GB SATA. OS is installed on SCSI (i.e. root & swap or on same scsi disk).

SuSe Linux 10.1 (x86_64) is installed (I have tried with 32 bit version of SuSe 10.1 & RedHat EL4 too, but the problem is same on these OS too).

thanks again,
ajit

Was the old processir on which things worked also a Xeon?

Since you get the same results on both Suse and RH. It sounds like it's a processor issue with the Kernel. Have you tried a Kernel compiled for the Xeon rather then one for the x86 family? The x86 instruction set is emulated on a Xeon processer.

[ajitup]

So it does mount the swap partition. At this point I do not know why it is not using it. Maybe someone who knows will reply. You could try to use swap file instead of swap partition
( http://www.europe.redhat.com/documen...ap-adding.php3), but I doubt it would make a difference.

Hi!

I tired this too ... did not solve the problem!

ajit