Why Can't enVision use a SAN connection
Hi Everyone -
This is a common question I hear from our customers. Why does enVision have to use NAS? Why can't we put an HBA card in the collectior?
It's a good question, and Matt Ward, one of the enVision PM's has a great answer.
Both NAS and SAN allow shared access to a disk.
NAS allows users to read and write the same files-there is something like CIFS or NFS to arbitrate who can read/write and overwrite.
SAN does not do file arbitration. It partitions the disk and lets each user access a different partition. If the LC is writing to the IPDB on one part of the SAN, the D-SRV cannot read it-can't even see it.
The "solution" would be to have the D-SRV ask for the data THROUGH the Collector. That is how it used to work on the 50 series and why the collectors got so loaded and performance was unpredictable. Yes it did "work" that way and it would work that way if we had one box to read and write but it puts stresses elsewhere on the system. NAS was the solution to those issues letting each component directly access the same data.
So the idea is, that by allowing the D-SRV access to the data, without having to go through any extra hoops we increase the performance and efficiency of the system. Plus, as enVision continually pushes forward in the Enhanced Availability model, it is important that different nodes are able to write, and access the event data.
Hope this helps, and please feel free to ask questions about this.
enVision can also utilise SAN storage through the use of a NAS gateway. These gateways basically present a 'slice' of the SAN and make it look like a NAS. They SAN is then accessed through a GB data mover just like a NAS.