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Hi I have been finding a fair bit of configuration
info iro clustering, cluster suite and gfs/2 but not quite seeing the more conceptual
stuff with pretty diagrams that would help me grasp whether its applicable to
my needs so I hope you can help with unscrambling my confusion. Currently I have 25 odd servers each running LAMP
and qmail etc. Throughput on each ranges from 1 – 10 mbits/s. Each
currently works off raid 1 mirrored disks and all are relatively low powered
machines. Total storage usage for all 25 machines is about 4Tb. I want to
virtualize the whole lot (I am leaning towards KVM). My motivations are 1)
reduce power usage in rack and 2) build in as much redundancy as I can. My thoughts have been to have 3 “front end”
physical host machines with a rough 50/50 split of the current 25 odd servers
into VMs on these physical hosts. I will then have redundancy across 3 machines
so that if machine 1 dies, the vms are moved to machine 2 or 3 pending fix of
machine 1. Then I want to create two “back end” storage servers
which are replicated and provide redundant storage to the front ends in a
primary/secondary way such that the front ends can failover to either available
storage server. I am anticipating having only VM host booting off machine1-3 and
using the back end storage servers for booting the vms and storing their data.
Each storage server will have 6 x 2Tb sata disks set up as a 6Tb raid1 array
although I have been reading that more spindles is better so maybe I need more
disks for optimal performance. Front ends and back ends would have multiple
bonded Gig e ports to a dedicated switch which I think should provide enough
bandwidth and the net facing NICs running off a separate switch. I have looked at openfiler and open-e for storage
platforms which are options but then followed some RHEL links to Cluster Suite,
GFS2 and the HA add ons and it began to look like another option for presenting
a redundant, automated-failover storage platform to the VMs using commodity
hardware rather than proprietary SAN kit. So I am trying to work out if I am on the right
track with Cluster Suite/GFS/ etc and if so, what are the elements I need to
meet my objective and will it actually work and provide the throughput I need
or are 25 web/mail servers doing constant reads/writes going to mean its all
too slow. I also saw some warnings about mysql usage on the cluster which
looked troubling. Any real world experiences, pointers or advice would be
great. Thanks and regards Ashley |
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