# How long will it take to purge my drive?

Q. “Dear Dr SCSI, I have a palette of 600GB drives. I need to zero out all blocks. How long will this take?”

A. That depends on two things, and is easy to calculate. Just follow the simple steps below.

## How long will it take?

The answer to this question depends on two things:

1. What is the size of the drive, and
2. How fast can you transfer data to the drive

## What size is the drive?

This one is pretty easy. We will do all of our calculations using megabytes (MB).
Your drives are 600GB, which in MB equals 600,000.
1 GB = 1,000 MB, 1TB = 1,000,000 MB
So – for calculations we will say that your drives are 600,000 MB size.
If you don’t already know what the size of your drives is, then go into STB Suite Original Mode and look at the drive display for your drive. In our example our drive is 1,953,513 MB (2 TB)

## How fast can I write data?

To determine your real-world data transfer speed we will use DMM. Go into the STB Suite Advanced Multi-Drive testing mode (DMM).
Select your drive in the Devices list, then click the Sys Thruput button –

DMM will run a quick non-destructive test and will display the average sustained data rate in the Test Progress window –

Our system with this particular drive can run at 136 MB/sec.
NOTE: if you will be zeroing out multiple drives, then select them all in the step above. The System Throughput test will display the real-world transfer rate which your particular test system can sustain with multiple drives.
Another NOTE: However, if you choose to use the WRITESAME zero method for zeroing out the drives then only select one of the drives and use that number in your calculations.

## “What’s the frequency, or time, Kenneth?”

Take the capacity of your drive (in MB), and divide it by the speed from above –

### Our test system setup

1,953,513 / 136 = 14,364 seconds, or 239 minutes, or about 4 hours.