SAN, the good, the bad, the failure

Storage Area Networks (SAN) uncouple the storage system from the physical server. The arguments for and against SANs being:

Should a server fail, simply roll in a new server, move the HBAs over from the failed server and boot. With hot-swap drive trays, it may actually be quicker to swap over DAS drives
A Fiberchannel SAN interface is faster Newer SAS drives on smart array controllers are arguably just as fast, or faster due to reduced communication overhead
SANs can be expanded without downtime DAS can be expanded, in many circumstances, without downtime
SANs shared storage ability results in greater utilization of the storage media NAS can also provide greater utilization of storage media
SAN hosts do occasionally fail. Their failures can affect the entire network architecture and are not quickly and easily recovered. Their failures, can also cause data corruption that., if using SAN replication, will be replicated to the failover SAN device.
SAN storage is much more costly than DAS

Since there is no way that I can justify the cost of installing multiple SAN hosts, or ensuring the data’s integrity, I’ve eliminated this option from my list of possibilities. It’s reliance on a single piece of hardware per storage cluster gives it the same reliability disadvantages as a DAS RAID1 mirror. The speed advantages it offers is better suited to high volume web sites and would be underutilized in our network.


~ by edwyseguru on March 26, 2009.

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