Backups on 200Gb/400Gb tapes

T

The_Unbeliever

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Hey

Does anybody know why a 200Gb uncompressed (compressed 400Gb) tape only take 180Gb's or so before getting ejected?

IMO those tapes must be able to take more than 200Gb's of uncompressed data, or is there some other funny business at work here? :confused:

The tape cover says 200Gb uncompressed, 400Gb compressed, so we should be getting an average of between 200Gb and 400Gb? The data is not even compressed.

Compression is enabled in the backup software. I have tried more than one pakage, they all average out on 180Gb's per tape.

Regards

Libs
 
Should they be able to store 200GB in Windows terms, or storage manufacturer's terms?
 
dj_jyno said:
Should they be able to store 200GB in Windows terms, or storage manufacturer's terms?
Click to expand...

Good point, whilst it says 200GB's, its closer to 185Gigs...with the filesystem also taking up space...
i would say this is about normal
 
Just enable compression on the tape drive and it will all fit on one tape?
 
Is this not another case of MegaBytes vs MebiBytes ??

You could lose about 20GB from the 200GB, leaving you with 180GB of actual space. It all depends on the manufacturers interpretation of what a MegaByte is.

Also, I'm not sure how they can make a claim of 200GB uncompressed, 400GB compressed. Data is data. Compressed data is still data, just in a slightly different form, that has been encoded according to a compression algorithm, and needs to be decoded according to it's corresponding decompression algorithm.

Compression/Decompression usually has nothing to do with the medium on which the data is stored, but rather with how the data is encoded. Unless I am missing something important.... ?
 
The problem is people confusing terminology, as usual.

Gb= Gigabit so I'll take it you mean gigaBYTE which is GB

Windows technically lists volume and file sizes in GiB. 1GiB= 1024MiB or 1048576 KiB or
1073741824 Bytes.

Drive manufacturers use 1000x1000x1000 instead of 1024x1024x1024 etc so if they say 200GB they mean
200000000000 Bytes. Divide that by 1024/1024/1024 and you get 186. something, thats the conversion from GB to GiB.

If this doesnt make sense, feel free to look up these terms on wikipedia or something...
No-one is trying to cheat you, thats just how the industry works, on different definitions
 
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TJ99 said:
No-one is trying to cheat you, thats just how the industry works, on different definitions
Click to expand...

Actually, the hardware manufacturers are trying to cheat you. MB and GB were defined a long time ago, and had a clear, unambiguous meaning. Then the hardware manufacturers barstardised the definition in order for it to appear as if they were giving you more space then what you are actually getting.
 
iCubed.Saajid said:
Actually, the hardware manufacturers are trying to cheat you. MB and GB were defined a long time ago, and had a clear, unambiguous meaning. Then the hardware manufacturers barstardised the definition in order for it to appear as if they were giving you more space then what you are actually getting.
Click to expand...

Bleh... I am NOT happy.

Might be worthwhile starting up a storage company and rip your clients off this way... :D
 
I use 400/800GB tapes, and get over 1TB on one tape...

Are you using hardware or Software compression?
 
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I also use the 200GB tapes, when enabling hardware compression I am able to fit over 200GB of data on the tape.

example file server has 300GB of data. -> Tape drive does compression -> data is now "165GB" -> fits on a 200GB tape.

so technically you are able to store 300GB of data on a 200GB tape as long as it is compressed.

sorry, hence the uncompressed 200GB storage or up to 400GB if the data is compressed first....
 
are the tapes formatted clean before you use them? there could be "overheads" copied to the tape before the backups start or there is other sessions on the tape. you might be appending to the tape instead of overwriting?!?
 
my 2 cents: If you do software and hardware compression you end up with overhead resulting in a bigger file.
 
This 400GB compressed / 200GB uncompressed branding is so stupid.

iCubed is soon going to launch its new range of CDs. 1.4GB compressed, or 700MB uncompressed. Order yours today!
 
iCubed.Saajid said:
This 400GB compressed / 200GB uncompressed branding is so stupid.

iCubed is soon going to launch its new range of CDs. 1.4GB compressed, or 700MB uncompressed. Order yours today!
Click to expand...

Really? 1.4GB WoW!!!!!!
And how many cd's do I need to get my 2.3TB backup done????
 
Tapes are formatted

Using both hardware and software compression.

Doesn't matter whether I use both, or only one - result is the same.
 
I have the same problem with my backups, I used to get 260GB on a 200GB uncompressed tape, but lately it stops at 203GB. Luckily my boss was able to convince the company to buy a new LTO4 tape drive with some 1.6TB tapes. :)
 
I get about 300 GB on my 200/400's

Remember though, you'll never get perfect compression.
 
Compression ( hard and soft )
Version of firmware on the physical will determine compression cabilty and ratio 1:1 , 1:2 etc same with the software as they have better compression built in
Type of data being backed up.

So many variables :(
 
Seems hardware compression gives good results.

Tape streamer packed up, it's in for warranty repairs.

And it's not cheap - R13k for an LTO2 tape streamer :sick:
 
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