Highlighted

B2D extremely slow?

Recently our tape library died, making all of our tape backups worthless as the model has been discontinued by Sony and it makes little sense to pay more than MSRP for used components.

So I thought I'd give backup-to-disk a chance and was considering using a collection of cheap USB drives instead of tapes.

I reasoned that the speed should be faster than tape, but instead I found that the tape drive was doing about 450-500 MB/min, while the B2D backup only recorded about 35 MB/min.  The full backup job we run on Saturdays usually takes 12 hours, but when I came in Monday morning I found the B2D job was still running after 35 hours and was only about 75% done.

Obviously this is unacceptable.

Is there something I am doing wrong?  I know USB is not as fast as SCSI, but even so it should be doing better than 35 MB/min right?
10 Replies

Hello Josh     Have you

Hello Josh 

   Have you tried recreating removable B2D ?

USB is too slow for this.See

USB is too slow for this.
See specs of USB: http://www.everythingusb.com/usb2/faq.htm#4 
The theoretic speed is 60 MB/s. In the link above you can see some comments that the effective throughput is around 40MB/s. That's around the speeds your are getting.

What you also can try is to get an esata disk (if you have an esate connection or controller), this will be much faster and will not be that expensive.

I wouldn't be complaining if

I wouldn't be complaining if I was getting 40MB a SECOND.  I am getting 40MB a MINUTE.  Now I don't expect Bexec to reach the maximum interface speed - especially for a chunk of data which is being passed over the WAN at ~ 2 MB/ sec.  But I would expect to be competitive or faster than tape, even if its USB vs SCSI.

Sorry, I didn't read

Sorry, I didn't read correctly the MB/Minute value.
But do not expect that an USB disk will be faster than a SCSI tape unit.

Agreed with teiva-boy. Wehave

Agreed with teiva-boy. Wehave tried USB drives on a number of occasions, and they have been so slow, it has seen a site being disconnected from Exchange/file shares etc.
Granted, we were desperate to have a backup device as the autoloader was royally poked, but we are now looking at Iomega NAS devices for the medium-term/long-term.
USB just doesn't give the required throughput...

What USB version?

Which version of USB is your server using?  If it's USB 1.0 then you're stuck at about 1MB/s.  USB 2.0 has the 35MB/s transfer rate.
To work around this until we move to new server hardware, we're backing up locally and then duplicating to the USB drive.  The backups finish quickly, and the copy to the drive is a little faster.

And v3.0 is theoretically

And v3.0 is theoretically capable of 4.8 GBps/38.5 Gbps   Figure 60% for sustained througput and you are looking at   ~2.9 GBps/23 Gbps

USB maxes out at 30 or MB/sec

USB 2.0 maxes out at 30 or so MB/sec for a single drive.  Have multiple USB drives on the same USB bus, and it'll go slower, as the 'S' in USB stands for serial.
So 30MB/min is slow, but not out of the question as being a hardware limitation in your case...  That said, USB vs. tape that is connected via SCSI/SAS/FC/iSCSI is almost always faster than USB anything!  

eSATA can be potentially much faster with better disks and configured correctly.


I'd suggest you do the following...  
Delete the B2D
Create a new partition using diskpart and make sure to use the align=64 switch (there are numerous how-to's on the web for this)
Format the volume using a larger allocation unit size than default
recreate the B2D.
Optional use eSATA (recommended)

Ultimately this is a hardware issue and not a BackupExec issue.  A good backup app is a great way to find the bottlenecks and mis-configurations in your systems.  

Anything USB is a bad idea as

Anything USB is a bad idea as reliable and fast storage.  While the interface is cheap and affordable, the protocol is very inefficient.  50% overhead is not unheard of...

what is 2.0 good for, about 480Mbps?  Thats, roughly 60MB/s, in real world you will never see more than 30-35MB/sec.

Other than for a personal PC, USB storage really has no place in a server.  There are much better alternatives in the form of eSATA, iSCSI, NAS, etc.  All can be had for a minimal price increase.


...well, my latest temporary

...well, my latest temporary USB drive is crashing away at a solid 35MB/m. On a server that holds over 400GB of data, and a 55GB Information Store, it should be finished with the backup this weekend =/