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Re: Moving MySQL to its own host

Hi there,

On 6/26/07, Craig Sanders <cas@taz.net.au> wrote:
On Tue, Jun 26, 2007 at 10:17:13PM -0400, Roberto C. Sánchez wrote:
>  - calling MySQL ACID compliant is a bit of a stretch

a huge stretch :-)
I'm a PostgreSQL user these days, but I thought MySQL + InnoDB is ACID

>  - if Apache is hammering your disk, then you very likely don't have
>    enough RAM (unless your website has gargantuan amounts of content
>    not in a database with a fairly uniform access pattern)
If you're using prefork and using a ton of RAM, then there will be a
lot less caching. Changing to a different MPM (in the case of Apache2)
might alleviate the problem?

i'm curious....in a virtual server system like xen or vmware, how is
disk-caching handled?

e.g. say you have a bunch of virtual machines, each allocated 256MB RAM, but
the physical hardware has, say, 2GB RAM.  is disk cached/buffered individually
by each virtual machine, or by the hypervisor kernel, or by both?
I would think, logically, both makes the most sense. The virtual
machines don't know that they're running on virtualized hardware. The
hypervisor kernel would only cache until the full system is running
out of memory (as it's being allocated to the individual virtual
machines), so... I think in the end it depends on what kind of
virtualization software you're using.


craig sanders <cas@taz.net.au>

Unseen University had never admitted women, muttering something about
problems with the plumbing, but the real reason was an unspoken dread that
if women were allowed to mess around with magic they would probably be
embarrassingly good at it ...
                -- Terry Pratchett, "The Light Fantastic"

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