When planning for storage to your VMware architecture, it is easy to focus on the storage capacity dimension rather than focusing on availability and performance

Capacity is generally not the limit for proper storage configurations. Capacity reducing techniques such as deduplication, thin provisioning and compression means you can now use disk capacity far more efficiently than before.

So what are IOP’s?

IOPS (Input/Output Operations Per Second, pronounced eye-ops) are a common performance measurement used to benchmark computer storage devices like hard disk drives (HDD), solid state drives (SSD), and storage area networks (SAN). As with any benchmark, IOPS numbers published by storage device manufacturers do not guarantee real-world application performance

IOPS can be measured with applications, such as Iometer (originally developed by Intel), as well as IOzone and FIO and is primarily used with servers to find the best storage configuration.

The specific number of IOPS possible in any system configuration will vary greatly, depending upon the variables the tester enters into the program, including the balance of read and write operations, the mix of sequential and random access patterns, the number of worker threads and queue depth, as well as the data block sizes.There are other factors which can also affect the IOPS results including the system setup, storage drivers, OS background operations, etc. Also, when testing SSDs in particular, there are preconditioning considerations that must be taken into account.

Computer IOP’s

Virtual Desktops use 5-20 IOP’s

Light Servers use 50-100 IOP’s

Heavy Servers – Require independent measurement for true accuracy

Storage Drive IOP’s

Enterprise Flash Drives = 1000 IOP’s pr drive

FC 15K RPM SAS Drives = 180 IOP’s per drive

FC 10K RPM SAS Drives = 120 IOP’s per drive

10K RPM SATA Drives = 125-150 IOP’s per drive

7K RPM SATA Drives = 75-100 IOP’s per drive

5.4K RPM SATA Drives = 80 IOPS per drive

Performance Characteristics

The most common performance characteristics measured are sequential and random operations.

• Sequential operations access locations on the storage device in a contiguous manner and are generally associated with large data transfer sizes, e.g. 128 KB.
• Random operations access locations on the storage device in a non-contiguous manner and are generally associated with small data transfer sizes, e.g. 4 KB.

Useful Performance Link

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