Re: [vserver] Copy-on-write Hard Links, Shared Libraries, Prelink and Memory

From: Gordan Bobic <gordan_at_bobich.net>
Date: Thu 10 Jun 2010 - 15:37:12 BST
Message-ID: <4C10F898.9080706@bobich.net>

On 06/10/2010 03:14 PM, Eugen Leitl wrote:
> On Thu, Jun 10, 2010 at 02:53:24AM +0200, Herbert Poetzl wrote:
>
>>> beryllium:~# df -k
>>> Filesystem 1K-blocks Used Available Use% Mounted on
>>> /dev/sda1 73742752 42989868 27006932 62% /
>>
>> this shows me that you do not favor a good design, as
>> putting _everything_ on one partition (including the
>> guests, which might need/want filesystem tagging sooner
>> or later) ...
>
> It's an experimental setup. It uses a 80 GByte SSD for / and
> vservers, and mirrors the 80 GByte to a 1 TByte WD RE3 drive
> as I've empirically learned that SSDs are not long for this
> world.

Depends largely on what you buy (random luck aside). Not all flash is
made the same. But as you are already doing, all important data should
be mirrored and backed up. :)

I tend to put all write-heavy areas that don't need to survive reboots
on tmpfs when I'm using flash storage. See my patches here:

https://bugzilla.redhat.com/show_bug.cgi?id=223722

What you want to put on tmpfs will vary according to what you have
installed and what the purpose of the system is, but in general, the
following are good candidates for moving off flash storage (or even
mechanical storage, for performance reasons):

/tmp
/var/lock
/var/run
/var/tmp

On my laptop, the above + /var/log (don't need /var/log to persist on my
laptop in most normal use-cases, but that's definitely not something to
do on a server!) I find that these save me about 250MB of writes just
for booting up and logging in (it's shocking how much KDE ends up
putting in /var/tmp).

Anyway, this is getting rather off-topic.

HTH

Gordan
Received on Thu Jun 10 15:38:51 2010

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