Backup time required for an image.

Hi everyone,
I do two full backups every week.One on an internal DD and the other one a USB Drive.
On my internal drive , the backup takes 31 minutes to run and on the USB, it takes 1 hour 19 minutes.
How can this be explained?
Thank you.

 

The transfer rate is much faster to an internal drive than through a USB connection.

 

Internal HDs are much faster than USB 2 external HDs. I don't think your times are particularly unexpected. The theoretical transfer rate of USB2, 480Mbps are never achieved in real-life. If you want an unscientific comparison the theoretical max USB transfer rate is about 1/3 of a SATA 1.5Mbps rate. This is very unscientific because you have to be very, very careful in comparing disk specs to make sure the apples are not being compared to the oranges.

 

Hi,
Thanks to both of you for these explanations.

 

Hello babac,

Thank you for using Acronis Products

Make sure that you are using USB 2.0 not USB 1.1. USB 1.1 speed is 12 mbit/sec and USB 2.0 max speed is 480 mbit/sec.

For example you backup 27 Gb. Let’s see what we have:
27 Gb = 27 000 Mb = 216000 Mbit (27000 *

Using USB 1.1 will take approximately 18000 sec = 300 min
Using USB 2.0 will take approximately 450 sec = 7,5 min

Backup time can be also influenced by high compression level.

Best regards,
--
Dmitry Nikolaev

 

Hi Dmitry,
Thanks for your reply.I'm using USB 2.0 and the compression level I use is ''normal''.
The difference in time required is rather high,I believe.

 

What is the size of the image .tib file or files after you have made the backup? My very rough rule-of-thumb is about 1GB/min of normally compressed archive to an internal HD. The actual value depends on the speed of your hardware and USB drives will be slower than an internal on the same system.

Dmitry's numbers are theoretical, there is no way you will get the example's rate of 3.6GB/min through a USB 2 connection in real-life.

 

Hi seekforever,
The compressed size of my backup is roughly 19.5 gb.

 

It seems a little slow but I was negligent in not asking you for the processor type/speed etc of your computer. In Windows my rule-of-thumb would have said about 20 minutes but that is only a rough estimate and with the latest and greatest desktop hardware it would be too slow an estimate.

Take one of your archive files that is residing on an internal HD and copy it using Windows Explorer to the USB drive and measure the actual time with your watch second hand. This will give you a baseline of time taken to copy a large file via USB on your system. Leave your AV or whatever running just as it is when you make an image in Windows when you do the test.

 

Hi seekforever,
Here's a description of my processor: AMD Athlon Dual Core,2,50 Ghz 2gb of RAM.
You will agree that this is rather good nowadays.