On 6/04/10 7:10 AM, Maciej Jan Broniarz wrote:
W dniu 10-04-05 22:43, jfar...@goldsword.com pisze:
Quoting Maciej Jan Broniarz <gau...@gausus.net>:
W dniu 10-04-05 22:08, Tonix (Antonio Nati) pisze:
Maciej Jan Broniarz ha scritto:
W dniu 10-04-05 17:45, Mike Jakubik pisze:
So first you have to define your workload, then define what errors you
must avoid or allow, and then define how to deal with failures, errors,
etc.
Then you can start talking about High Availability vs. level of Fault
tolerance, vs. ....
Let's say i need to run a few php/sql based web sites and I would like
to maintain uptime of about 99,99% per month. No matter how good the
hardware - it will always fail at some time. My goal is to build a
system, that can maintain that uptime.
From what You say I need some level of HA system, to maintain the
required uptime.
So, as I've said earlier (correct me, if I'm wrong) - the setup could
look something like that:
- 2 web servers with carp
- 2 storage servers with on-line sync mechanism running
- 2 mysql servers with on-line database replication
(i'm skiping power and network issues at the moment).
Few people have told me about a setup with linux, drbd and heartbeat
which offers them some level of HA. Has anyone tried anything similar on
FreeBSD?
We've recently set up a new colo facility with the following:
* dual ethernet links from our upstream
* dual HA pfSense (FreeBSD) boxes running haproxy to load balance incoming
requests amongst live web servers
* dual switches
* 2 (or more) web (application) servers
* database
Until we get to 'database' everything is HA and quite easy to build and manage.
Having a clustered database solution is expensive and beyond most smallish
budgets. mysql and postgresql don't have anything available that is quite ready
yet (IMO), so you'll need to be talking to the bigger (expensive) players about
their clustered offerings.
You need redundancy within the database application across multiple machines.
Possible, but not easy. You aren't going to be doing that completely within the
operating system itself. DRDB sort of gets you there, but DRDB isn't
synchronous with the database activity, so you might still lose data.
A cheaper option is to use master-slave replication (postgresql and mysql offer
this) and CARP failover (just don't fail back!). But it hasn't been quite
robust enough for my liking.
Ari Maniatis
--
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Aristedes Maniatis
ish
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