Hi,
On 2/4/2010 3:17 PM, Bo Lynch wrote:
Right know we have about 30 or so linux servers scattered through out
or
district. Was looking at ways of consolidating and some sort of
redundancy
would be nice. Will clustering not work with certain apps? We have a couple mysql
dbases,
oracle database, smb shares, nfs, email, and web servers.
Each app has it's own best way to provide the redundancy and auto-failover and it's own set of tradeoffs of the added complexity vs. the possible reduced downtime if the primary fails.
I'd balance the options against the low-tech method of having raid mirrors in swappable bays with a spare similar server chassis or two around plus regular backups kept at a different location. The raid lets you continue in the likely event of a disk failure so you can repair it at a convenient time. Other failures (motherboard, power supply) are less likely but can be handled by swapping the drives into an alternate chassis (and with Centos you'll need to re-assign the IP addresses that are tied to the old NIC mac addresses) with a small amount of downtime. And the backups cover things like operator or software errors (that would wipe a cluster too) or a building-level disaster that destroys the disks or the primary and spare chassis at the same time. Some apps may be worth the effort to do better.
In our configurations we utilise different strategies depending on what we want to achieve as there isn't really a panacea for this... We use virtual servers, hot standby firewalls/routers, load balanced servers, warm standby servers (using such things as mysql replication, rsync and DRBD to keep the boxes in sync) and shared storage from disk arrays and servers with local disk arrays for local performance and resilience. We have also utilised hadoop (distributed filesystem) on some again to provide resilience within the limitations of hadoop.
S.