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Old 02-25-2012, 08:15 PM
 
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Can anyone explain to me why a data center would use Virtual Tape Libraries, as opposed to simply storing on disk?
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Old 02-25-2012, 08:34 PM
 
Location: Central Texas
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Perhaps the #1 reason is that they have thousands of processes, scripts, programs, etc. that were originally designed to use tape. So using virtual tape is a painless way to move away from physical tape to disk without the cost of changing code or processes.
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Old 02-25-2012, 09:35 PM
 
396 posts, read 971,241 times
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Originally Posted by hoffdano View Post
Perhaps the #1 reason is that they have thousands of processes, scripts, programs, etc. that were originally designed to use tape. So using virtual tape is a painless way to move away from physical tape to disk without the cost of changing code or processes.
Wow, I guess I don't know much about tape! I know there are robotic libraries, but I would think those could be replaced by software controls across a SAN or NAS. I can't imagine why so many processes, scripts and programs would be necessary for tape.
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Old 02-26-2012, 07:18 AM
 
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Originally Posted by Pooua View Post
Wow, I guess I don't know much about tape! I know there are robotic libraries, but I would think those could be replaced by software controls across a SAN or NAS. I can't imagine why so many processes, scripts and programs would be necessary for tape.

Not sure about the current costs comparisons but tape was used because tape is cheap, if you're making backups it's an obvious choice for large volumes of data. Consider the cost of mini DV tape, $2 or $3 and that can store about 14GB of data using standard play. Technically you can extend that substantially, some camcorders have option for long play to double or triple the amount of storage.... think I've even seen it for six hours of storage.

The tape simply moves slower and unlike it's analog counterpart quality is exactly the same using regular play or long play. I should mention that long play on DV camcorders can become problematic because of errors, the slower speeds narrow the window for error control and those tapes might not be playable in other machines or even become unplayable in the same machine over time because of mechanical slop.
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Old 02-26-2012, 08:18 PM
 
Location: Central Texas
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Quote:
Originally Posted by Pooua View Post
Wow, I guess I don't know much about tape! I know there are robotic libraries, but I would think those could be replaced by software controls across a SAN or NAS. I can't imagine why so many processes, scripts and programs would be necessary for tape.
A mainframe "script" that controls very important work could have coded into it something like "UNIT=TAPE" - and changing it 100 times times 1000 is not something they take lightly. The script might be written for backups that chain many files on a single tape cartridge. The concept of stacking files on a single tape is widely used, and won't work if you just change the script to "UNIT=DISK"
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Old 02-27-2012, 07:21 PM
 
Location: Diaspora
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Quote:
Can anyone explain to me why a data center would use Virtual Tape Libraries, as opposed to simply storing on disk?
Actually they are stored usually in a StorageTek (or IBM) robotic storage cabinets that are filled with 1TB tapes (cabinet holds 1000's). Users data is seperated into different locations on that tape or across different tapes depending on its security level. The data center and storage facility are not in the same location. Also the data has a reduntant backup in another state or country. If another level of security is required then copies will be ejected and sent to IronMountain (or something similar).

Quote:
Not sure about the current costs........
$160 each
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Old 02-28-2012, 02:04 AM
 
396 posts, read 971,241 times
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Originally Posted by NeilVA View Post
Actually they are stored usually in a StorageTek (or IBM) robotic storage cabinets that are filled with 1TB tapes (cabinet holds 1000's). Users data is seperated into different locations on that tape or across different tapes depending on its security level. The data center and storage facility are not in the same location. Also the data has a reduntant backup in another state or country. If another level of security is required then copies will be ejected and sent to IronMountain (or something similar).
I think you are talking about robotic tape libraries. Virtual tape libraries don't use tapes.
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Old 02-28-2012, 07:24 AM
 
Location: Diaspora
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I think you are talking about robotic tape libraries. Virtual tape libraries don't use tapes.
They use disks for data needs to be readily available at all times and tapes for data that doesn't. I use the word cabinet because its easier to visualize than a library. In either case the disk/tape needs to loaded into a drive which currently take a couple of seconds. This technology is nearly the same as it was five years ago, but has jumped from MB storage to TB storage. The difference now is that the current way of cataloging the information is to a virtual tape number which has 10,000's of them on a physical tape/disk which itself has a physical label robotically scannable inside of a cabinet. Thus each disk/tape is holding Trillions of pages of alphanumeric data.

Now there is new technology that is considered tapeless. Problem here is the cost of the cabinet and its drives. Thus now instead of multiple companies having their own tape libraries, they now share a location. These new locations are mostly staffed with security guards and contain less than 10 IT people onsite on any given 24-hour day who deal with any physical problems. The software side is in India with also less than 10 people at a time to answer phone calls or emails.

Last edited by Pruzhany; 02-28-2012 at 08:03 AM..
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