How much do corporate IT departments typically chargeback to the business for each GB of storage?
To give you some idea about how much this number can vary, here are the 'total cost of storage per GB' numbers for two of our storage arrays:
- Array 1: >$25/GB
- Array 2: >$9.50/GB
- Array 3: >$2.50/GB
Biiiiiig difference. Why the difference?
- Array 1 uses Fibre Channel drives with an average size of 273GB, and an average cost of $1900/drive.
- Array 2 uses FATA drives with an average size of 931GB, and an average cost of ~$800/drive.
- Array 3 uses SAS drives with an average size of 750GB, and an average cost of $420/drive.
Arrays 1 & 2 have the same backup rotation, so those costs are the same per GB. The first array is actually higher, since there are some costs I don't have access to and wasn't able to include in my amortization math. Neither cost includes the cost of the Fibre Channel infrastructure that supports the storage environment.
Array 3 is not yet in service, so we don't know what the backup costs are for that one yet. It's special.
As for figuring out what we'd charge for storage, part of that depends on our back end accounting practices which favors one time costs. We're pushing to get a yearly cost in place. That number would be the above numbers amortized over the expected life-span of the array, plus a replacement premium so we can keep up with the ever increasing levels of service people expect from storage, allow changes of backup vendor (always a lot more expensive to change horses than keep on the one you're on), and otherwise catch costs not directly included in these 'total cost of storage' numbers.
Theres not going to be a simple answer to this, your costs you charge to business are going to be dependant on any number of things such as:
- Physical Hardware Costs
- Support Costs
- Environment Costs
- Replacement Parts
- Response Times
The IT department is going to need to consider what their storage infastructure is costing them per GB, and charge the business an amount based on this. If you have a dedicated storage team, with hundereds of SAN devices your overall costs are going to be higher than a single NAS device in a small business, but if your spreading this over a large bussines the charge per GB may be lower.
It depends on;
- make of storage
- access type (FC, iSCSI, NFS etc)
- speed of disks
- RAID levels
- backup options provided
- level of discount from supplier
- ongoing support costs
- any additional infrastructure required to provide storage (switches, racks, shelves, cabling, software etc.)
- whether man-power costs are to be included or sunk already
- whether margin is expected to be added or whether it's sold at 'cost'
So these could easily range from just the purchase cost of a new small, slow, disk (i.e. <£100/$50 for 500GB) to entirely outsourced DB-spec FC storage with backup at the same cost for a single GB.