Why is it said that /var should reside on a separate partition from /
usr ?

Le 14.10.2008 08:31, annalissa a écrit :
> Why is it said that /var should reside on a separate partition from /
> usr ?

For instance: /var is the place where logs are written, suppose some
process becomes mad and fill the partition with logs....

--
François Patte
Université Paris Descartes

On Tue, 14 Oct 2008 08:50:06 +0200, François Patte <francois.patte@mi.parisdescartes.fr> wrote:

>Le 14.10.2008 08:31, annalissa a écrit :
>> Why is it said that /var should reside on a separate partition from /
>> usr ?
>
>For instance: /var is the place where logs are written, suppose some
>process becomes mad and fill the partition with logs....

And /usr may be mounted read-only.

Grant.
--
http://bugsplatter.id.au/

François Patte wrote:
> Le 14.10.2008 08:31, annalissa a écrit :
>> Why is it said that /var should reside on a separate partition from /
>> usr ?
>
> For instance: /var is the place where logs are written, suppose some
> process becomes mad and fill the partition with logs....
>
Yes. /var is for /variable/ data. Logs and often databases live there.

So it can grow and possibly exceed limits: having it separate from the
parts that are necessary for recovery from such a state, means you CAN
recover..

Grant <g_r_a_n_t_@dodo.com.au> wrote:

> And /usr may be mounted read-only.

And /var may be mounted noexec.

Mark.

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Quinton, BIRMINGHAM.
B32 1QE.

annalissa <aarklon@gmail.com> wrote:
> Why is it said that /var should reside on a separate partition from /
> usr ?

Because the root "/" filesystem should never be allowed to fill up.
If it does, all kinds of nastiness can occur.

And var is one of the partitions on which programs dump their data,
especially e-mail and news, web proxies, log files, etc.

It's a safeguard.
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annalissa <aarklon@gmail.com> writes:

>Why is it said that /var should reside on a separate partition from /
>usr ?

Many things are said. Not all are sensible.
Anyway, /var/ is written to. /usr is in general not. So /var can fill up.

=?ISO-8859-1?Q?Fran=E7ois_Patte?= <francois.patte@mi.parisdescartes.fr> writes:

>Le 14.10.2008 08:31, annalissa a écrit :
>> Why is it said that /var should reside on a separate partition from /
>> usr ?

>For instance: /var is the place where logs are written, suppose some
>process becomes mad and fill the partition with logs....

So what? /usr is not written to, and you can read from a full partition.
And /var is far more likely to fill up if it is on a separate partition
(that spare space on /usr is not available to it).



>--
>François Patte
>Université Paris Descartes

François Patte wrote:
> Le 14.10.2008 08:31, annalissa a écrit :
>> Why is it said that /var should reside on a separate partition from /
>> usr ?
>
> For instance: /var is the place where logs are written, suppose some
> process becomes mad and fill the partition with logs....
>

And /var/spool/mail, /var/spool/news, /var/spool/mqueue and /var/tmp/. Any of
those may be overflowed quite badly.

The separation of /var also goes back to the days of much smaller disks, when
a modest mail spool would be wise to put on a separate disk or partition.

On 2008-10-14, Unruh <unruh-spam@physics.ubc.ca> wrote:
>=?ISO-8859-1?Q?Fran=E7ois_Patte?= <francois.patte@mi.parisdescartes.fr> writes:
>
>>For instance: /var is the place where logs are written, suppose some
>>process becomes mad and fill the partition with logs....
>
> So what? /usr is not written to, and you can read from a full partition.
> And /var is far more likely to fill up if it is on a separate partition
> (that spare space on /usr is not available to it).

That's just the reason to separate /var from the rest of the filesystem.
One reason to separate /usr from the rest of the filesystem is to make
upgrades easier; you can mke2fs the /usr partition to wipe all vestiges
of old binaries clean and start fresh. (Grant already mentioned another
reason, the ability to mount /usr read-only.)

--keith


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