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We've got a DL380p Gen8 with 16 slots for 2.5" drives, and we're running out of storage space.

So what I'm looking at doing is replacing all of the current drives (some are 300GB, some 600) with larger capacity drives and also adding a D2700 enclosure for additional capacity.

My question is: If we're using a 6GB/s D2700 and SAS drives in all of the above, does it matter what logical drives and such are in the server as opposed to the enclosure?

It seems to me that the SAS drives in the server will each have their own channel running at the full 6 GB/s, whereas the drives in the enclosure will have to share a connection back to the server at 6GB/s?

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up vote 3 down vote accepted

D2700 provides four physical interfaces per SFF port, each 6gb/s, which gives total 24gb/s per one physical port. In multipath configuration it can provide up to 48gb/s when using two HP HBA's and two storage controllers.

So, from the performance point of view - nothing changes to the worse when using D2700, also, you are getting more availability.

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So if I'm understanding this right, there's no downside to using a disk enclosure or having your OS drive be on those disks rather than the ones on the server itself. – Sean Long Sep 4 '13 at 17:58
Yes, you are only limited by the possibilities of the storage controller like number of logical volumes, chunk sizes etc. Physical connectivity with D2700 gives more than you can achieve with Smart Array PCI controllers. Even standard FC can't be that fast, it only can give you 8gb/s per port (16gb/s for multipath). – GioMac Sep 4 '13 at 18:04

You'll want to keep the arrays in the external enclosure separate from those inside the server. Just from a fault-domain perspective.

However, you can have boot disks in the enclosure or have the server itself be empty. Up to you. The D2700 enclosure is a rock-solid unit, so the advantage when using SAS disks is dual-porting/dual-pathing, depending on which host RAID controller you're using.

Your SAS connections are multi-lane 6Gbps links on a SFF-8088 connection. That's 24Gbps. You'll probably be doing this with one controller.

Remember that a single (spinning) disk's throughput won't approach 6Gbps, so oversubscription is fine in this case.

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