SAN or DAS Hyper V Performance

Posted on 2015-01-28
Medium Priority
Last Modified: 2015-02-02

We currently have 2 Hyper-v hosts (IBM X series) with local attached storage. In total we have 14 VM's.
Each VM acts as a RDP Host and provides access to an ERP Solution based on SQL & MS Access.

We had some issues lately with local drives and we are looking into replacing our DAS with a entry level SAN cfr IBM v3700. (We like to do live migration , replication....)

The SAN should host all 14VM's . The 2 hosts don't have an SAS HBA to connect with the SAN. So the only option would be to use the 1GB iScsi port. Would this be fast enough to provide access to all of our VM's ? Or should we consider to buy an IBM 6Gb SAS HBA for each host ?

For the replication part we want to use Veeam backup & replication on a 3rd host seperate host. The backup repository should also be on the SAN if possible.

Can you provide use some advice what would be the best scenario ?
Question by:computercenterbel
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LVL 41

Accepted Solution

Philip Elder earned 1000 total points
ID: 40575265
DAS is better in my experience. Why?

Dual 6Gb SAS HBAs in each node yields an aggregate 96Gb of virtually zero latency bandwidth.

Plus, it is very simple to set up using Microsoft's MPIO. No iSCSI bandwidth restrictions, latency, and complexity.

We've been building DAS based clusters since about 2008. First with Hyper-V and now with Hyper-V with a Scale-Out File Server cluster backend (VHDX over SMBv3). In our testing a pair of SAS cables from one node gets maxed out at about 377K IOPS (4KB at various Read/Write and thread/queue depths). iSCSI can't touch that.
LVL 126
ID: 40575320
DAS, you can get a HP SAS SAN, which is dual attached (direct attached!)

Author Comment

ID: 40575611
with das I meant local attached storage to the server like an internal sas drives on the ibm server.
would a san get better performance then local drives attached to the server?
We only have 2 physical hosts
LVL 41

Expert Comment

by:Philip Elder
ID: 40575684
Here is how we do it: 2 Node 1 JBOD Hyper-V Cluster Connectivity Guide. It includes pictures and instructions on connecting everything together. In this case we have an asymmetric cluster configuration with storage arbitration handled by Storage Spaces (JBOD = way _LESS_ dollars than shelf). Dell MD1220 is their version. We use DNS-1640 DataON JBODs.

The guide would be applicable to connecting a storage shelf (P2000MSA dual SAS, MD3220 Dual SAS). In this case storage configuration and management would be handled by the onboard software.
LVL 126

Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 1000 total points
ID: 40575725
Performance of DAS (or direct attached SAS MSA 2000) will be faster than an iSCSI SAN, or NAS!

If you require performance, although there are now caching functions, for Read and Write, for NAS and iSCSI SANs!

How many IOPS do you need for your VMs ?

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