Disk space capacity planning for SQL Server Database.

I have a task to provide a disk space capacity planning for our databases to enable the network team size the disk appropriately for our SQL database. Just to make sure this is done and done right; I decided to ask for help on this forum.

Please take a look at my current database size and use both compound growth and Compound growth with compounding growth rate to help me determine what amount of space this database will be requiring in the next five years should we grow at 20% each year using the following formula.

Compound growth: This model assumes that the growth rate is based on a percentage growth rate rather than a fixed growth amount. As the size of the database increases, so will its future growth amount because each increment is a percentage of the current database size. A database of 100MB that grows 10 percent per year would be 110MB at the end of the first year but 121MB at the end of the second year. Use the following formula to calculate compound growth:

FDisk = CDisk X (1+Rate) N

In this formula, the terms are defined as follows:

FDisk = future disk space required

CDisk = current disk space used

Rate = percentage growth rate per period

N = number of periods.

Compound growth with compounding growth rate This model assumes that as the database grows, so does the growth rate. For example, suppose we expect the database to grow by 10 percent this year but we expect that the growth rate itself will also increase every year by 20 percent. That means that next year, the growth rate will be 12 percent. The first year, therefore, a 100MB database will grow by 10MB. In this case, the 10MB is called the initial increment and the 20 percent is called the incremental rate of growth. Use the following formula to calculate this model:

FDisk = CDisk + (Init X (1 ā IncRate) (N+1))), (1 ā IncRate)

In this formula, the terms are defined as follows:

FDisk = future disk space required

CDisk = current disk space used

N = number of periods

Init = initial increment of growth

IncRate = incremental rate of growth per period

Reference book: SQL Server 2008 Administration Instant Reference

Example of my database:

Currently allocated space 77127.00 MB in size

Available free space 11776.31 MB now

Auto growth in Megabytes 1,500 MB or 20% either one is fine

Maximum File size Unlimited

I suggest that you round up everything and stay in GB - the estimation is approximate enough.

Your equation assumes linear growth. That is, the same customers more or less maintain the same transaction volume more or less.

Otherwise if the business is growing, then you need n to be a power instead of a multiplier or something like that.

Current DB = 76GB

Add 23% free space in database => 94GB

at end of first period => 104GB

And the disk to house 105GB of database => 131 of disk.

Note that I've rounded up a few times.

Now, what about your backups - which disk are they on? Are they compressed? Don't forget to take account of them.

Regards

David