[ale] LAMP performance

[Greg Freemyer]

On Mon, Sep 13, 2010 at 2:51 PM, mike barnes <mdb3624 at gmail.com> wrote:
> I have been asked to come up with a solution for a 6 sigma application that
> can have up to 1 million transaction/hour.

300 transactions a second.  Seems doable, but obviously high performance.

> Since, I have not done a lot of work in the LAMP arena, I thought that I
> would see what issues I will be having using the following platform.
> L --> Centos 5.x
> A --> Apache latest
> M --> MySQL Carrier Grade Engine with Solid State Drives

I wonder about SSDs.  They can only handle a fixed number of
transactions per lifetime.  They use wear-leveling to smooth it out,
but a 128KB erase block can typically only take 50,000 writes per
lifetime.

Does anyone know if that ends up being a real world limitation or not?

At a minimum I'd want to research that aspect.  But I suspect new
generation SSDs will handle it fine.

> P --> Latest
> Issues that I think I need to consider
> Application level --> Data cacheing, bytecode cacheing
> Database --> large memory foot print to hold most of database to alleviate
> disk IO

SSD "reads" are not resource intensive and don't shorten the lifetime
at all, aiui.  So I'm not sure you should pay both for a large memory
foot print and SSDs.

ie. a fast SSD may be able to handle 25,000 read io's a second, so it
should be able to keep up with 300 transactions/second even if most of
the db is not ram resident.

> Backup and replication --> Based on my reads from the web, this will be
> handled seemlessly by the database engine.
>
> What am I missing?
>
> Thanks in advance for your thoughts.
> Mike
>
>
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Greg Freemyer
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