Good morning,
If you haven't already, please open a case with Dell/Equallogic support. If you haven't installed SANHQ yet, please do. That's downloadable from the Equallogic support site. www.equallogic.com
Since this original posting, support has found some common configuration changes that can improve performance.
1.) Update to most current build of ESX. (I've seen updated network drivers help)
2.) Disable Delayed ACK
3.) Disable Large Receive Offload
4.) If you are using VMDK/RDM disks, create a virtual SCSI adapter for each one. (Up to 4 per VM)
5.) For SQL, Exchange, Sharepoint, consider using the MS iSCSI adapter directly connecting to an EQL volume vs. VMFS
6.) Align the NTFS partitions (if not done by default), AND set the filesystem cluster size to 64K. This will match the 64K stripe size on the array 7.) Also, you can try the "Paravirtual" Virtual SCSI adapter on the data VMDK disks or Raw Device Mapped drives. On active disks, the paravirtual can provide better performance.
8.) The switch infrastructure configuration should be reviewed as well.
Hope this helps.
Regards,
Don