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Home > Archive > Red Hat Topics > September 2005 > Optimum swap partition
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Optimum swap partition
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| Stan Brown 2005-09-13, 2:46 am |
| The FC3 install (which I aborted for other reasons) griped at me
about not having a swap partition, but one of the local LUG members
said it wasn't necessary since I'm not planning to run zillions of
programs at once.
I've seen advice elsewhere that a swap partition should be double the
size of RAM; I've got a gigabyte of RAM. But I see from other
articles here that a large swap partition can make Fedora run
erratically.
I'd be grateful for some advice.
--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://OakRoadSystems.com/
"What in heaven's name brought you to Casablanca?"
"My health. I came to Casablanca for the waters."
"The waters? What waters? We're in the desert."
"I was misinformed."
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| Jan Gerrit Kootstra 2005-09-13, 2:46 am |
| Stan Brown wrote:
> The FC3 install (which I aborted for other reasons) griped at me
> about not having a swap partition, but one of the local LUG members
> said it wasn't necessary since I'm not planning to run zillions of
> programs at once.
>
> I've seen advice elsewhere that a swap partition should be double the
> size of RAM; I've got a gigabyte of RAM. But I see from other
> articles here that a large swap partition can make Fedora run
> erratically.
>
> I'd be grateful for some advice.
>
Stan,
The rules I use the size of swap:
If RAM<=1GB: swap=2*RAM
If RAM>1GB: RAM=<swap<=2*RAM
Exception: if Oracle is installed, add 150MB per concurrent user.
So in your case: take something between 1GB and 2GB. 2GB is preferred,
if you have the discspace.
Swapping only slow your system, if it used. If your applications do not
need swap then the system does not slow down.
In general the size of the swapspace does not slow down the system, but
the amount of swapspace used.
Kind regards,
Jan Gerrit Kootstra
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| Jean-David Beyer 2005-09-13, 7:46 am |
| Jan Gerrit Kootstra wrote:
> Stan Brown wrote:
>
> Stan,
>
>
> The rules I use the size of swap:
>
> If RAM<=1GB: swap=2*RAM
> If RAM>1GB: RAM=<swap<=2*RAM
>
> Exception: if Oracle is installed, add 150MB per concurrent user.
>
> So in your case: take something between 1GB and 2GB. 2GB is preferred,
> if you have the discspace.
>
> Swapping only slow your system, if it used. If your applications do not
> need swap then the system does not slow down.
>
> In general the size of the swapspace does not slow down the system, but
> the amount of swapspace used.
>
Even the amount used is not the criterion, but the paging rate. I have 4 Gig
RAM and my needs are modest (most of the time), so it seldom pages at all. I
have 8 Gig swap space, spread over 4 10,000rpm Ultra/320 SCSI hard drives.
Most days it does not page at all. Only when I run IBM's DB2 DBMS does any
paging take place, and that is because I have it configured so it can get
the working set of the index into RAM for slightly faster performance. Even
then, it only does a few pages per second when starting up. At the moment:
Swap: 8193076k av, 9596k used, 8183480k free
--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key: 9A2FC99A Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 08:00:00 up 90 days, 1:57, 4 users, load average: 4.05, 4.15, 4.18
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| Stan Brown 2005-09-13, 5:52 pm |
| On Mon, 12 Sep 2005 22:28:41 -0400 in linux.redhat.misc, I asked...
>
> I'd be grateful for some advice.
Thanks for the speedy responses. I do have plenty of free disk space,
and it sounds like what I heard is not accurate (too much swap file
degrading performance), so I'll go with 2GB to match my 1GB of real
RAM.
Once I get the install done and start poking around, I'm sure I'll
find a way to show the paging file stats, so I can find out if that
2GB is actually getting used. (Don't tell me the command yet; I'd
like to find it for myself.)
--
Stan Brown, Oak Road Systems, Tompkins County, New York, USA
http://OakRoadSystems.com/
"What in heaven's name brought you to Casablanca?"
"My health. I came to Casablanca for the waters."
"The waters? What waters? We're in the desert."
"I was misinformed."
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