[nylug-talk] Recommendations for encrypted tape drive(s)?

[Alex Pilosov]

On Wed, 5 Mar 2008, Ruben Safir wrote:

> On Wed, Mar 05, 2008 at 05:26:14AM -0500, Alex Pilosov wrote:
> > On Tue, 4 Mar 2008, Luis Murillo wrote:
> > 
> > > Yes, you would need some fiber setup with multiple drives and also keep
> > > in mind that the place where you keep your data that you want to backup
> > > must also provide the data as fast as possible...for example over the
> > > network on a 100MBit network don't expect to reach 163MBps speed on one
> > > drive...
> > Really bad things happen when you confise bits and bytes.
> > 
> > Tape drive bandwidth is quoted in bytes per second. LTO speed is 120MB/s.
> > Big B. Bytes. The "163MB/s"  figure is "expected speed with compression" 
> > 
> > Network performance is quoted in bites per second, or Mbps. Little b.
> > 
> > Thus, 100Mbps network will only sustain 12MB/s write speed. Even single GE 
> > is not enough to sustain LTO-4 performance. 
> 
> 
> bites, kilobits and megabits are also all not equal in scale.
> a kilobyte 1024 bits and a megabyte is is even more distorted.
I wasn't even getting into that one (the 2.4% thing is important but 700%
is far more important), but since you brought it up.

Yes, tricky things that you have to keep in mind.

Network performance is measured in powers of 10. Thus, gigabit is exactly 
1,000,000,000 bits per second.

Hard drives used to be measured in powers of 2 or 10, randomly, but
recently, manufactures to inflate capacity moved to powers of 10. Thus,
500GB hard drive is really roughly 500,000,000,000 bytes. (Used to be,
though, 536,870,912,000 - a 7.3% difference).

Flash drives are measured in powers of 10.

Floppy drives are measured in powers of 2. (sort of).

Optical media is measured in powers of 2 for CDs, but powers of 10 for
DVDs etc.

RAM is always quoted in powers of 2. 

(yes, technically, we should be talking in gibibytes and mebibytes, when
we actually mean units of 1024, but imho, those are retarded, and nobody 
uses it).