 | | | Linux AS 3 swap question!! | Linux AS 3 swap question!! 2006-02-26 - By A.Fadyushin@(protected)
Back
You can decrease (or increase) the size of swap partition using the same
method as for any other partition (e.g. repartition that part of disk
with fdisk). Of course, you should disable that partition (with
'swapoff' command) before changing its size, recreate its structure with
'mkswap' after changing the size and enable that partition using
'swapon'.
You can use both swap partition(s) and swap file(s) at the same time in
any combinations - e.g. 1 swap partition and 1 swap file, or 2 swap
partitions and 1 swap file, etc.
I think that a swap partition is a better approach because the access to
partitions is faster than access to the file. Swap partition and swap
file will survive the reboot. Swap partitions are exist as long as them
exist in the disk's partition table and marked as swap partitions in
/etc/fstab (entry in /etc/fstab is necessary for automatic enabling of
that partition on startup, even without such a entry the partition could
be enabled with 'swapon'). Swap files are exist as long as them are not
deleted (for example, using 'rm') from the filesystem (the entry in
/etc/fstab is used the same way as for swap partitions). Neither swap
partitions nor swap files are automatically deleted by the system.
Alexey Fadyushin
Brainbench MVP for Linux
http:///www.brainbench.com
__ ____ ____ ____ ____ ____ ____
From: redhat-install-list-bounces@(protected)
[mailto:redhat-install-list-bounces@(protected)] On Behalf Of mac
Sent: Sunday, February 26, 2006 8:36 AM
To: Getting started with Red Hat Linux
Subject: Re: Linux AS 3 swap question!!
Appreciate your response ..Thanks ..i juts have a couple of queries
1)i have a swap partion of 16 GB ...how can i go about decreasing the
size of this partition ie the size of swap
2)Can both the swap file and partition coexist ??
3)WHich is a better approcah ..partition or file and which exists after
every reboot
Really appreciate your help here
Thanks
On 2/26/06, Rick Stevens <rstevens@(protected)> wrote:
On Sat, 2006-02-25 at 23:09 +0530, mac wrote:
> Hi,
> We have a Linux EL AS 3 running on a poweredge server with 8 GB
> ram ...we would like to know how to change the swap space on a linux
> AS 3 system dynamically
>
> and would AS3 support a swap size of 16 GB
>
> any pointers appreciated
You can have up to 16 swap sections but each is limited to 2GB each,
giving a total of 32GB of swap. You can't change the swap size
dynamically, since the swap is on a fixed-size partition or file. You
can enable and disable various swap files or partitions using the
swapon(8) or swapoff(8) commands.
Swap has to be either a separate partition OR a zero-filled file. You
probably know how to make a swap partition. To create a swap _file_:
1. Find a partition that has enough free space for the swap you want.
2. As root, do:
# dd if=/dev/zero of=/path/to/swap/file count=size
For example, to create a 2GB swap file called "/var/swapfile":
# dd if=/dev/zero of=/var/swapfile count=2G
3. Convert the file to a swap file:
# mkswap /var/swapfile
3. Activate via:
# swapon /var/swapfile
4. Edit your /etc/fstab file and add a line for this swap file so it'll
activate on the next boot:
/var/swapfile swap swap defaults 0 0
Voila!
-- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- --
- Rick Stevens, Senior Systems Engineer rstevens@(protected) -
- VitalStream, Inc. http://www.vitalstream.com -
- -
- God is real...........unless declared integer or long -
-- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- --
__ ____ ____ ____ ____ ____ ____ ____ ____ ____
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<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>You can decrease (or
increase) the size of swap partition using the same method as for any other
partition (e.g. repartition that part of disk with fdisk). Of course, you
should disable that partition (with ‘swapoff’ command) before
changing its size, recreate its structure with ‘mkswap’ after
changing the size and enable that partition using ‘swapon’.<o:p></o
:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>You can use both swap
partition(s) and swap file(s) at the same time in any combinations – e.g.
1 swap partition and 1 swap file, or 2 swap partitions and 1 swap file, etc.<o
:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>I think that a swap
partition is a better approach because the access to partitions is faster than
access to the file. Swap partition and swap file will survive the reboot. Swap
partitions are exist as long as them exist in the disk’s partition table
and marked as swap partitions in /etc/fstab (entry in /etc/fstab is necessary
for automatic enabling of that partition on startup, even without such a entry
the partition could be enabled with ‘swapon’). Swap files are
exist as long as them are not deleted (for example, using ‘rm’) from
the filesystem (the entry in /etc/fstab is used the same way as for swap
partitions). Neither swap partitions nor swap files are automatically deleted
by the system.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span><
/font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Alexey Fadyushin<o:p></o
:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>Brainbench MVP for Linux
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'>http:///www.brainbench
.com<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-US
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span><
/font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
redhat-install-list-bounces@(protected)
[mailto:redhat-install-list-bounces@(protected)] <b><span style='font-weight:
bold'>On Behalf Of </span></b>mac<br>
<b><span style='font-weight:bold'>Sent:</span></b> Sunday, February 26, 2006
8:36 AM<br>
<b><span style='font-weight:bold'>To:</span></b> Getting started with Red Hat
Linux<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: Linux AS 3 swap
question!!</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Appreciate your response
..Thanks ..i juts have a couple of queries<br>
<br>
1)i have a swap partion of 16 GB ...how can i go about decreasing the
size of this partition ie the size of swap<br>
<br>
2)Can both the swap file and partition coexist ?? <br>
<br>
3)WHich is a better approcah ..partition or file and which exists after every
reboot<br>
<br>
Really appreciate your help here<br>
<br>
Thanks<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><span class=gmailquote><font size=3 face="Times New Roman">
<span
style='font-size:12.0pt'>On 2/26/06, <b><span style='font-weight:bold'>Rick
Stevens</span></b> <<a href="mailto:rstevens@(protected)">rstevens
@(protected)</a>>
wrote:</span></font></span><o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>On Sat, 2006-02-25 at 23:09 +0530, mac wrote:<br>
> Hi,<br>
> We have a Linux EL AS 3 running on a poweredge server with 8 GB<br>
> ram ...we would like to know how to change the swap space on a linux<br>
> AS 3 system dynamically <br>
><br>
> and would AS3 support a swap size of 16 GB<br>
><br>
> any pointers appreciated<br>
<br>
You can have up to 16 swap sections but each is limited to 2GB each,<br>
giving a total of 32GB of swap. You can't change the swap size <br>
dynamically, since the swap is on a fixed-size partition or
file. You<br>
can enable and disable various swap files or partitions using the<br>
swapon(8) or swapoff(8) commands.<br>
<br>
Swap has to be either a separate partition OR a zero-filled
file. You <br>
probably know how to make a swap partition. To create a swap _file_:
<br>
<br>
1. Find a partition that has enough free space for the swap you want.<br>
<br>
2. As root, do:<br>
<br>
# dd if=/dev/zero
of=/path/to/swap/file count=size <br>
<br>
For example, to create a 2GB swap file called "/var/swapfile":<br>
<br>
# dd if=/dev/zero
of=/var/swapfile count=2G<br>
<br>
3. Convert the file to a swap file:<br>
<br>
# mkswap /var/swapfile<br>
<br>
3. Activate via:<br>
<br>
# swapon /var/swapfile<br>
<br>
4. Edit your /etc/fstab file and add a line for this swap file so it'll<br>
activate on the next boot:<br>
<br>
/var/swapfile
swap swap  
; defaults 0
0 <br>
<br>
Voila!<br>
<br>
-- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- --<br>
- Rick Stevens, Senior Systems Engineer <a
href="mailto:rstevens@(protected)">rstevens@(protected)</a> -<br>
- VitalStream,
Inc.
<a href="http://www.vitalstream.com">http://www.vitalstream.com</a> -<br>
-
-<br>
- God is real...........unless
declared integer or long -<br>
-- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- --<br>
<br>
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