[ale] who is eating my drive

[Lightner, Jeff]

The old rule of thumb used to be two time RAM = swap.   For Linux I've
seen it suggested 1 to 1.5 times is adequate but have run across many
that don't bother at all.  As for me I always build swap because I
believe it is better to have it and not need it than to need it and not
have it.

I've never heard it suggested that virtual memory hurts performance.
In fact it benefits it because you can preallocate more "memory" to
processes than physically exists.   A lot of what is preallocated is
never actually used.   

Remember "swap" is a historical name.   Back in the bad old days entire
processes "swapped" out to disk to run there.   Now swap space is used
for "paging" instead so it only pushes out old memory blocks to disk
(and ideally never calls them back in).  The only time swap *seems* to
"hurt" is when you're truly memory constrained and actually begin doing
excessive page outs/pages ins.   In that case the issue isn't the swap
but rather the lack of memory (or an excessive use of memory by runaway
processes or the like).


-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of JD
Sent: Tuesday, May 31, 2011 2:05 PM
To: Atlanta Linux Enthusiasts
Subject: Re: [ale] who is eating my drive

Is having a swap device larger than 2GB useful for 99.98% of users?

Seems if you use that much virtual memory, performance would start to
suffer.

For most of my VMs, I don't give **any** swap. I can ensure no over
commitment happens.




On 05/31/2011 01:28 PM, Narahari 'n' Savitha wrote:
> Thanks for all your time.
> 
> Here is the output of the fdisk -l command
> 
> devusr at devusr-virtual-machine:~$ sudo fdisk -l /dev/sda
> 
> Disk /dev/sda: 22.5 GB, 22548578304 bytes
> 255 heads, 63 sectors/track, 2741 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x00075d29
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sda1   *           1        1698    13630464   83  Linux
> /dev/sda2            1698        2742     8386561    5  Extended
> /dev/sda5            1698        2742     8386560   82  Linux swap /
Solaris
> 
> 
> 
> So what should I be looking here for ?
> 
> -Narahari
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