[wp-hackers] Load Balancing | Media Uploads to Multiple Servers

[Steve Pellham]

Great points Eric.  Thanks.
On Thu, Aug 6, 2009 at 11:56 AM, Eric Marden <wp at xentek.net> wrote:

>
> On Aug 5, 2009, at 1:29 PM, Steve Pellham wrote:
>
>  Thanks for the input Eric...
>>
>> So what happens when the 'central location' gets cutoff from the world:
>> massive communication failure, hardware failure, fire, [insert your own
>> disaster here]?
>>
>
> You can always set up IP Failover of that box to another hot spare for that
> data. But there is quite a bit of difference between rsyncing stuff you
> don't have to, and having a central mount where changes are reflected live
> for all systems that read that mount. I've also had a lot of success using
> Fuse to mount S3. Performance is great, and you can configure it with a
> local cache in the case of S3 outage. And there is something really cool
> about having 200 TB+ mount point on your server. ;)
>
> http://xentek.net/articles/448/installing-fuse-s3fs-and-sshfs-on-ubuntu/
>
>
>  A central location for the site isn't acceptable if that 'central
>> location'
>> (I'm guessing you mean some sort of NAS/Network Storage) gets cutoff from
>> the world.  I'm speaking in terms of separate www/db servers that are
>> geographically dispersed.  If the 'web heads' both pulled from a central
>> location (easier to maintain... but...) there is still a single point of
>> failure.
>>
>
> Don't confuse High Availability with High Capacity with Load Balancing.
> They are distinct, and have different approaches to solve.
>
>
> However, if you are trying to eliminate all points of failure, then you're
> going to need a few servers, with every service/server having a hot spare
> and redundant backups of data to be able to bring it back up quickly and
> reliably. Adding in geographically aware edge serving will complicate
> things, but your static content, including wp-content/uploads, should
> probably live on a true CDN anyway if this is one of your concerns.
>
>  I fail to see how not replicating data (mysql, application, content data)
>> across multiple servers prevents a single point of failure.
>>
>
> It seems that the more advice that comes in the more requirements get
> revealed. What I described can and will serve you and can be used in HC
> configurations, and includes a quick DR (Data Recovery) plan, provided you
> have off site backups of uploads (s3 is good for this) and could stand up
> another box in its place (or keep a hot spare handy) with minimal
> effort/downtime. Its all a balance between budget and practicality. In the
> scenario I've suggested and implemented dozens of times, its generally the
> web heads that get swamped and go down, not the DB/File server (which
> generally has more memory than the leaner web heads). MySQL replication is
> not as great as it could be and has its own trade offs that I like to avoid
> unless maximum failover is the name of the game.
>
>
>
> - Eric Marden
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