Check the performance of your storage repository

Ref: http://support.citrix.com/article/CTX121634

[root@FsXENSVR109 ~]# ll /dev/disk/by-id/ | grep <SCSI ID>   NOTE: SCSI ID can be found on the 'General' tab of your SR in XenCenter

The output of this command will be something like the following:

lrwxrwxrwx 1 root root  9 Feb 12 19:16 scsi-36000d3100087d3000000000000000005 -> ../../sdb

Once you have this information you can execute the following command

[root@FsXENSVR109 ~]# hdparm -t /dev/sdb

/dev/sdb:
 Timing buffered disk reads: 248 MB in  3.06 seconds =  81.08 MB/sec
[root@FsXENSVR109 ~]# hdparm -t /dev/sdb