On Tue, Sep 16, 2003 at 11:25:36PM -0600, Rodolfo J. Paiz wrote: > Tape is old, linear, slow, EXPENSIVE, and it breaks. Nasty stuff, no > one should use it anymore really. You want size, get a 160GB for $100 > ($0.625/GB), and by the way you'll get way more speed than tape would > ever give you along with the neat non-linear access, real-time speed, > yadda yadda yadda. You want an off-site backup? Put the drive in a > removable case.
Bzzzt. Thanks for playing :-)
Tape has its place. In the home, sure, tape is usually not needed, but in the enterprise, somehow the thought of backing up my systems with multi-terabyte disk farms to disk and keeping multiple images lying around doesn't seem practical without tape. We're up to about 200 220GB tapes in one of our libraries and it's growing, not shrinking.
I recently set up a NAS box for a customer, using a Promise chassis and 15 250GB drives, which resulted in 3.25TB real useful space and cost a total of $6,000 (overall cost per GB: $1.85). These numbers include a hot spare drive and the parity drive, so only 13 drives are "useful" and the box should be really, really, really reliable.
For comparison, I would like to ask: what is the cost per gigabyte of using large tape libraries (say, for 3TB like I'm doing above), and what percentage of companies actually use more than 3TB of storage today? Or more reasonably, how many exceed 6TB or even 10TB, since I will argue that the simplicity of operation, real-time, non-linear access, far greater speed, etc. of the hard drive as backup medium will extend to having two or even three of these boxen at least.
From what little I know (feel free to correct), tape is going to be monstrously more expensive in this size range, and it still has all the disadvantages I mentioned above. Yes... I am sure that there is some definition of "enterprise" at which huge tape libraries become indispensable, but there has to be some very serious storage and money involved and I'd still have to be convinced.
Tape, properly configured, is not slow. Most modern tape drives these days have the ability to outperform disk drives. Writing at 10-15MB/sec is not uncommon.
So what's your point? EVERY new disk drive I have bought easily hits 20-25 MBps so I still cannot see how tape is faster. But if speed is what you want, will tape outperform disk arrays like my RAID-5 box above? Using GigE for connectivity, I have been able to clock well over 50MBps on just a few scratchpad trials from this RAID box to my notebook; and that's _network_ transfer, not internal transfer. I will admit that 10-15 MBps is not "slow", but it is indeed "slower" and even "significantly slower". And I haven't even really pushed this box yet... I honestly don't know if or how much faster I can move data.
Certainly the guy asking whether cpio or tar is a better backup strategy is nowhere near any realm where tape MIGHT be better. Heck, I know a company with $2.5 BILLION in sales and 12,000 employees who just filled up their first 2TB array and are about to add another. There is no way, Ed, that telling this guy to use tape is better advice! Don't argue with me on blind theory... help the poor slob solve his real problem.
-- Rodolfo J. Paiz [EMAIL PROTECTED]
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