|
![](/i/fill.gif) |
On Tue, 10 Nov 2009 10:12:57 +0000, Invisible wrote:
>> There's
>> nothing, though, that says you can't create a mirrored set, let the
>> drives mirror, and then "break the mirror" and take one drive offline.
>> I've known people who have done that and used that for disaster
>> recovery when upgrading systems.
>
> This is a very, very dumb way to do backup. A file-level copy will be
> drastically faster. (It doesn't involve mirroring all the useless empty
> sectors.) IME, mirroring a disk typically takes something like 10 hours,
> regardless of capacity. (Lower-capacity drives are usually
> correspondingly slower too.)
>
> Also, if you do a file-level copy, you have options such as compressing
> the data and putting multiple backups on a single backup harddisk, doing
> differential or otherwise partial backups, and so forth.
Depends on what you're trying to accomplish. If the purpose is fast
recovery, mirroring is a very good way to ensure you have a workable
system if you swap the drives out.
Doing a file-level copy might be faster, but then you get to go in and
muck about with permissions afterwards. Mirroring takes care of all of
that for you.
Remember - I've got decates of working with server technology behind me
here. ;-)
>>> An often-encountered backup strategy is to copy everything onto an
>>> external USB HD and then put that somewhere. I'm not sure that all
>>> this turning the drive on and off won't just wear it out faster.
>>
>> See my anecdotal evidence in reply to Stefan. Two identical units, one
>> powered on and off regularly, one that was left on 24x7. Guess which
>> one failed? Not the one that has been turned on and off regularly for
>> 5 years now. The one that was plugged in and running for 3 years
>> solid.
>
> In theory, until the disks are spinning at full speed, you don't get
> that "cushion of air" for the heads to "fly" on, which should result in
> wear. Of course, no doubt manufacturers know all about this and have
> come up with ways to at least reduce the problem...
I would expect they do. I used to know a guy who worked for Quantum
years ago (I wonder what he's up to these days), and he said the
engineering was quite impressive.
Jim
Post a reply to this message
|
![](/i/fill.gif) |