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What swap is my system running on?


 
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# 1  
Old 03-29-2006
MySQL What swap is my system running on?

hi all,
i need to know what swap my system is running on...
Sun-Fire-880 is my system...
physical memory= 16GB (8 CPU's)

i know generally we keep swap 2 times of real memory...
i want to know what is current swap my system is running?

following is the o/p of swap -s:
Wed Mar 29 16:08:08 IST 2006
total: 4368952k bytes allocated + 2234496k reserved = 6603448k used, 23508432k available

thanks & regards
abhijeet
# 2  
Old 03-29-2006
Quote:
i need to know what swap my system is running on...
What is that you are actually looking for?

swap you are mentioning is the partition that you have on your IDE.
If it;s the file system that you are referrering to with respect to swap then it is the Linux Native Swap file system itself
# 3  
Old 03-29-2006
swap -l
will list the swap devices. Not sure if that is what you want, though... Smilie
# 4  
Old 03-31-2006
MySQL

Firstly,
i know my swap areas on disk.
i wanted to know "swap" in physical form of memory.

swap -l doen not include swap space in the form of physical
memory because this space is not associated with a particular
swap area.

but swap -s does include swap space from all configured
swap areas as listed by the -l option, as well swap
space in the form of physical memory.

thats what i had pasted o/p of "swap -s" ..
i am confused about those terms" allocated" ,"reserved","used" & "available"
what if i add up "used" & "available" values ,does it give my "swap" in form of physical memory?

mayb i m yet to understand concept of swap fully....!!!

regards
abhijeet
# 5  
Old 03-31-2006
Swap is only loosely associated with physical memory. You would be better off forgeting about physical memory while you look at those numbers. Those swap areas that you know about on disk...they add up to your total swap space. Some of your total swap space may be in use...if so, this is known as "used swap space". But you you may have some swap space not yet in use...if so, this is called "available swap space". The "used swap space" may actually have stuff written to it...that is "allocated swap space". The kernel know exactly where the allocated swap space is. There may be some stuff in physical memory that has never been swapped out, but is potentially swapable...some swap space has been "reserved" for this stuff. The kernel only has a counter for "reserved swap space". If and when "reserved swap space" is needed it will become "allocated swap space". Allocation takes some time and kernel delays it. Lots of stuff come into core and never really need to swap. So no allocation will ever be done.

You might have swap space equal to 3 times physical memory. And you can potentially run out of swap anyway.

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