This article describes how to evaluate the read speeds of the Storage Repository (SR) of block device, including LVM, LVM over HBA, iSCSI, NetApp and Dell EqualLogic.

Requirements

• Ensure that the SR is configured properly and for NetApp or Dell EqualLogic type, at least one virtual disk is created.
• Access to the console Command Line Interface (CLI).

Instructions

To evaluate the read speed, complete the following procedure:

1. Find out the device path/name of the corresponding SR from XenCenter or the output of the following command: 
   fdisk -l

2. On the XenServer console, run the following command: 
   hdparm -t <device path, e.g. /dev/sda>
   
   OUTPUT:
   [root@labserver ~]# hdparm -t /dev/sda
   /dev/sda:
    Timing buffered disk reads: 422 MB in  3.01 seconds = 140.43 MB/sec
    

3. Test multiple times (preferred) and use the average as a more accurate result.

4. As a general guideline, regular or acceptable performance for different SR types are as follow:

   • Local SATA, SCSI drive or SAS (Serial Attached SCSI): 70 Megabytes per second or above.
   • Fibre Channel over HBA: 70 Megabytes per second or above
   • iSCSI or other Gigabit Ethernet based block device: 30 Megabytes per second or above
   • iSCSI over HBA: 40 Megabytes per second or above

Note: These are the general guidelines, the real throughput on different scenario might be slightly different. However, any read rate significantly slower than guideline levels would be too slow and problematic.