1 Copper

Basic Server - EMC SAN Configuration Question

We have video servers connected to an EMC SAN and had a drop in recording which ended up being a fiber switch issue (we now know we should have a redundant switch).

The question is, why do we need a switch for a SAN backup unit and servers that are in racks right next to each other, why can't they be directly connected by fiber, Ethernet cable, or a specialized cable of some sort?

Thanks, their is probably a simple answer we should have known in the first place.

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3 Zinc

Re: Basic Server - EMC SAN Configuration Question

SAN switches serve many of the same purposes of Ethernet switches.  They serve to buffer traffic when needed and help ensure delivery.  If an Ethernet switch receives a bad frame, it can assist by having a client retransmit a frame.  The same is true for SAN switches as well.

While you can directly connect the FC HBA on a host to an FC storage array or tape library, it is often best practice to put a switch between those devices.  If switches are used, it is often best practice to use two switches to ensure redundancy. Depending on how many HBAs and FC ports are available in each server, you may not have enough ports on your storage array or backup device, hence a switch - or better yet, a redundant pair of switches - allows you to connect many servers to just a handful of storage ports.

Let us know if that helps!


4 Ruthenium

Re: Basic Server - EMC SAN Configuration Question

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3 Cadmium

Re: Basic Server - EMC SAN Configuration Question

Generally, a Mid-range SAN comes with 4 to 8 Host Port which means if you are to connect your servers directly to your Storage then you can connect up to 16 non-redundant Hosts or 8 redundant Hosts directly.


- It saves the cost of procuring fibre channel switch.

- Useful for SMB environment


- Scalability is limited.

However, if you now add let's say a basic 2 x 8/24 switches in between you can connect more than 8 redundant Hosts on your SAN + add backup devices as well.

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