[nycbug-talk] off site backup

[alex at pilosoft.com]

On Sun, 30 Oct 2005, Jerry B. Altzman wrote:

> On 10/30/2005 1:53 PM, alex at pilosoft.com wrote:
> > Disk drives fail in different ways. It is uncommon for drive not to
> > spin up after 1-2 years of shelf life - it is the *power on hours*
> > that usually kill you. Yes, there are certain failure modes that
> > result in drive being completely inaccessible - motor burning out,
> > failing bearings, broken head - but those are fixable (at about 1000$
> > cost) by a competent guy with a donor drive, a soldering gun and a
> > screwdriver. ;)
> 
> Given the engineering of drives, they *do* tend to like running all the
> time, or being off, but the torque to spin up from zero can be damaging.  
> (So can dropping it.)
rotating/seeking will eventually kill your motor/bearings.

> > Keep in mind that usually, with hard drives, it isn't hard to
> > implement a RAID system where failure of one drive doesn't impact your
> > entire system - much harder than tape, as you need >1 tape drive to
> > make it happen.
> 
> Multi-tape-drive jukeboxes mitigate this nicely.
It is however quite unusual to have raid tapes. (i.e. you would need 3 
tape drives, and 2 out of 3 tapes to do restore). I've never heard of 
anyone doing that.

> > Keep in mind that media for tape (say, ~40$ for LTO 200G) is about 1/4
> > of cost of similar hard drive media.
> 
> with transfer rates correspondingly lower :-)
Eh, I think it's close enough. LTO has 70MB/sec transfer rate. 7200 
RPM drives have ~60MB/s, 10k rpm ~80MB/s

> > So, its really apples and oranges. For historic (say, you have to do
> > once a week backup and store it offsite, with retention of 1 year) -
> > it doesn't make sense to do hard drives. For near-line and on-line,
> > you want to use hard drives.
> 
> Hard drives are the way to go if you have a time-to-recovery on the
> order of minutes instead of hours (or hours instead of days).
> 
> With recordable DVD media being relatively cheap, is anyone archiving to
> *that*?
The DVD jukeboxes began to appear fairly recently (as in 1-2 years ago). 
Unfortunately, the density is still not there - as in, 100-DVD changer is 
"only" 470GB. This might change with dualside duallayer DVDs...

-alex