‎Poor disk performance | DELL Technologies

Poor disk performance

We have a two nodes Microsoft Windows Server 2012 Hyper-V cluster using a dual SAS controller MD3200. Everything is working fine in the cluster, but the disk performance seems to be very por.

We have defined three disks groups:

- First is a RAID-5 with four SAS-II 15K 3.5" disks; we have defined here only one SAN virtual disk, and we have formated it with CSV and assigned it to the cluster. This SAN virtual disk hosts six fixed size VHDs with the system partition of six Windows Server 2008 R2 VMs.

- Second is a RAID-1 with two SAS-II 15K 3.5" disks; we have defined here only again one SAN virtual disk, and we have formated it with CSV and assigned it to the cluster. This SAN virtual disk hosts two fixed size VHDs with the data partition of two Windows Server 2008 R2 VMs. This servers are database servers, and needs the best performance we can get. The second one server is defined as a standby server, so we can say that any time this SAN virtual disk has only one VHD working.

- Thrid disk group is a RAID-5 with two NL-SAS 7k2 3.5" disks; we have defined here four SAN virtual disks, all formated with CSV and assigned to the cluster. We have defined here same VHDs with less working requeriments.

The problem is that the data VHD of the main database server are performing very bad talking about access to disk, so we try to test and make some changes. We made HD tune tests moving this VHD to the SAS RAID-5 disk group, to the SAS RAID-1 disk group, to the NL-SAS disk group and to one ISCSI LUN assigned from one low-cost SATA NAS used for backups (surprise: this was the best HD tune results by far!!!). The tests were done with no workload in the system (all servers ruynning, but without users and without processes running).

I'm including the HD tune test results.

Dell support is telling us that this IOPS results are normal, but I think that they are very poor, and I can not find any explanation to the comparative of the dell SAN tests results against the SATA NAS tests result.

Can someone please confirm me that this is the best that the MD3200 can do it? If I must expect better IOPS results, any idea of what can be going wrong with our setup?

Thanks.

1) NL-SAS RAID-1 SAN: