Sizing a Storage Solution

Sizing is a basic requirement for any Storage Solution's.
A low cost Storage Solution or even an over sized,  flash based solution may be improperly sized which would impact the cost, performance and scalabilty of the solution.

We need to have the knowledge of the driving needs of the customer before recommending the solutions & for this we need to work closely with the customer to build a strong bond which delivers excellent outputs for a long term relationship.

From storage perspective what are essential inputs for sizing  are Capacity requirement, throughput,IOPS/Sec, Read/ Write Percentage, Block Size, Data consitency (Server HBA to Disk) & most important the customer budget.

Throughput (MB/sec) = IOPS * Block size (MB)

IOPS is measured by the number of I/O operations, i.e. READs and WRITEs, per second,

• Per Disk IOPS is the rated IOPS of a single SATA/SAS/FC disk of varying RPMs. 
• Frontend IOPS is the IOPS of the application, installed on storage LUN, which consumes storage. This is the IOPS classification used when talking about a requirement for 100, 200, 1,000, or 1 million IOPS. 
• Backend IOPS is the IOPS required by the storage subsystem to deliver the required frontend IOPS and is dependent on RAID penalties.

RAID PENALTY : WRITEs to a disk are complete only when the data and the parity information have been fully written to the disk, extra time is required for writing the parity information. This extra time is called the RAID penalty.

Hence from the table it is clear that the READ PENALTY does not change only the WRITE PENALTY is impacted and increases to 6 in case of RAID 6 configurations.

Storage Solution also varies based on parameters of performance &, capability. Generally speaking Server infrastructure are higher in their demand for storage space but VDI infrastructures on performance.