6.0.1

Table 1‑103. Disk I/O Performance Enhancement Advice (Continued)
# Resolution
4 Use the vendor's array tools to determine the array performance statistics. When too many servers simultaneously
access common elements on an array, the disks might have trouble keeping up. Consider array-side improvements
to increase throughput.
5 Use Storage vMotion to migrate I/O-intensive virtual machines across multiple hosts.
6 Balance the disk load across all physical resources available. Spread heavily used storage across LUNs that are
accessed by different adapters. Use separate queues for each adapter to improve disk efficiency.
7 Configure the HBAs and RAID controllers for optimal use. Verify that the queue depths and cache settings on the
RAID controllers are adequate. If not, increase the number of outstanding disk requests for the virtual machine by
adjusting the Disk.SchedNumReqOutstanding parameter. For more information, see vSphere Storage.
8 For resource-intensive virtual machines, separate the virtual machine's physical disk drive from the drive with the
system page file. This alleviates disk spindle contention during periods of high use.
9
On systems with sizable RAM, disable memory trimming by adding the line MemTrimRate=0 to the virtual
machine's VMX file.
10 If the combined disk I/O is higher than a single HBA capacity, use multipathing or multiple links.
11 For ESXi hosts, create virtual disks as preallocated. When you create a virtual disk for a guest operating system,
select Allocate all disk space now. The performance degradation associated with reassigning additional disk space
does not occur, and the disk is less likely to become fragmented.
12 Use the most current host hardware.
Virtual Disk Requests (Number)
The Virtual Disk Requests chart displays virtual disk usage for the virtual machine.
After you click Overview on the Performance tab of the virtual machine, you can view this chart by
selecting Home from the View drop-down menu. It is available at collection (display) levels 3 and 4.
Table 1‑104. Data Counters
Chart Label Description
Read Requests Number of virtual disk read commands completed on each virtual disk on
the virtual machine. The aggregate number of all virtual disk read
commands is also displayed in the chart.
n
Counter: numberRead
n
Stats Type: Absolute
n
Unit: Number
n
Rollup Type: Average
n
Collection Level: 2
Write Requests Number of virtual disk write commands completed on each virtual disk on
the virtual machine. The aggregate number of all virtual disk write
commands is also displayed in the chart.
n
Counter: numberWrite
n
Stats Type: Absolute
n
Unit: Number
n
Rollup Type: Average
n
Collection Level: 2
Virtual Disk Rate (KBps)
The Virtual Disk Rate chart displays virtual disk usage rate for the virtual machine.
After you click Overview on the Performance tab of the virtual machine, you can view this chart by
selecting Home from the View drop-down menu. It is available only at collection levels 3 and 4.
Chapter 1 Monitoring Inventory Objects with Performance Charts
VMware, Inc. 75