why ubuntu LTS installs all in a single partition?

[Christofer C. Bell]

On Sat, Aug 3, 2013 at 5:59 AM, Mauro Sanna <mrsanna1 at gmail.com> wrote:

> On 3 August 2013 05:13, Christofer C. Bell <christofer.c.bell at gmail.com>wrote:
>
>> On Fri, Aug 2, 2013 at 1:24 PM, Liam Proven <lproven at gmail.com> wrote:
>>
>>> On 2 August 2013 19:14, Mauro Sanna <mrsanna1 at gmail.com> wrote:
>>> > You don't use swap on servers too?
>>>
>>> It's a fileserver. Just a fileserver. With 3GB of RAM, it doesn't /need/
>>> swap.
>>>
>>> Just for an easy life, I have the full Unity desktop on there, too. It
>>> idles at under 500MB of usage. In other words, full loaded, it uses
>>> about one-sixth of its memory: the rest is disk cache.
>>>
>>> Who needs swap any more?
>>>
>>
>> While it may work for you, a blanket recommendation to have no swap
>> should be avoided.  Please look into how Linux handles memory allocations
>> (specifically look into vm.overcommit_memory and vm.overcommit_ratio).  For
>> modern Linux systems with large amounts of RAM, a good rule of thumb is to
>> have 2GB of swap.
>>
>
> 2G of swap?
> If I have a large amount of ram why do I need so much swap?
>

I'm not sure under what circumstances one would consider 2GB to be a lot of
swap.  I would encourage you to look into how Linux manages memory.
Specifically vm.overcommit_memory and vm.overcommit_ratio.  The purpose of
having 2GB of swap is to give your system some buffer virtual memory so
real processes that end up requesting more physical RAM than you have
available, yet will not use it, will still be able to start.

For example, let's say you have 8GB of RAM in your system.  Currently, 6GB
of RAM are in use (leaving 2GB free).  You want to start a process that
will use no more than 1GB of physical RAM when running, but will request
3GB of memory for itself, exceeding the availability of physical RAM by
1GB.  Without swap, this program will not start, and the kernel will give
you an insufficient memory error (ENOMEM).  With a 2GB buffer provided by
swap (so the system's total virtual memory size is 10GB), this program will
be able to request 3GB of RAM (as 4GB are available), be started, and
happily use the 1GB of RAM it really needs.

-- 
Chris

"If you wish to make an apple pie from scratch, you must first invent the
Universe." -- Carl Sagan
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