Hadoop is Shared Nothing architecture. SAN Storage usually goes against the grain for distributed storage in a distributed compute environment.
The only central storage we support so far is Isilon because we did some joint engineering with them. Even then, DAS has its advantages (as well as disadvantages mainly because of 3 factor replicator). The main issue is that compute nodes where YARN spins up containers, for every data access needs, having it on separate SAN disk means that every query or access would then have to go over network speeds and would no longer be distributed across the spindles on the storage nodes. That not only decreases access time it introduces more points of failure through switches and creates additional potential for bottleneck.
Normally I would have also compromise a bit for master nodes but I
just came from a client who did VMs with SAN for master nodes and
performance started great but once multiple users came on board and the
master nodes needed to handle more blocks, performance tanked. We
wasted a week and a half moving the master components to physical nodes
on a cluster with data. Painful.
See a good discussion here: http://searchstorage.techtarget.com/video/Understanding-storage-in-the-Hadoop-cluster
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