[Discuss] Possible backup scenarios for a 500GB drive

[Alan W. Irwin]

On 2007-10-23 23:25-0700 John Blomfield wrote:

> Alan W. Irwin wrote:
>> 
>> I am buying a desktop, and I agree your suggestion is also a good backup
>> possibility for that case, but one key advantage of external drives is you
>> can store them off-site to help guard against the case of a fire or some
>> other office disaster.  Also note that both the rsync and dump/restore
>> methods are fast (they only deal with changed files after the first use) 
>> so
>> I don't think the speed advantage of internal drives is going to be of
>> paramount importance.
>> 
>> Alan
> Yes, that's true but it does depend on how large your incremental files are, 
> and how often you need to renew your "full" backup.  If you think you need a 
> 500GB drive that sounds like a lot of data to me and my experience of backing 
> up over my network with rsync tells me that you might find the time 
> significant.  I don't know how the speed of a 100Mb network compares to USB. 
> I now have a 1Gb router so I hope to speed up my transfers when I upgrade my 
> computer NIC's.

I cannot conceive how I am going to fill a 500GB drive, but that is what I
said about my 1GB, 2GB, 7GB, 25GB drives in their era, and also my current
80GB drive.  However, I think it is a good prediction that the files on the
500GB disk will only accumulate or change slowly so that any given run of
rsync or dump will not have much to do.  USB 2.0 has a theoretical transfer
rate of 480Mbs according to http://www.everythingusb.com/usb2/faq.htm so it
is 4.8 times faster that 100Mbit networking, and 6.25 times slower than the
3Gbps SATA II.  Of course, the factor of 6.25 is an overestimate of the
speed ratio for the same drive interfaced with either USB 2.0 or SATA II
since most drives have sustained data rates that are considerably less than
3Gbps.

> Another option for off site storage is to install your backup 
> drive in a removable tray but you do need to shut down and reboot when you 
> remove the drive and possibly reset the BIOS options, unless you invest in a 
> more expensive "hot pluggable" drive.

That sounds like a good alternative suggestion as well.  Has anybody here
had practical experience with this option or the external USB drive option
discussed above?

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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