Maximum capacity of LTO tapes

[n2nuk]

Hi there,

Our backups have failed over the last few days, when we go to the unit in the morning, the tape has already ejected and a 'media mount failed' error description is reported by Veritas.

I am currently backing 350GB using 200GB tapes that can hold up to 400GB when compressed. I have a feeling that the 400GB is the maximum and may only be achievable under certain conditions.

Does anyone know if this is the case, it looks like I am going to upgrade to the 800GB beast!

Many thanks

Naz

 

[LWComputingMVP]

I'm impressed if you're getting 350 GB out of 200 GB tapes. It's really foolish in my opinion to base your backup capacity planning on advertised compressed capacities of tape. It's RARE you see 2:1 compression - it's rare you see 1.5:1 compression if you're backup up "normal" data such as office documents and related information. Some databases can use compression better, but if you want to be safe, IGNORE the compression numbers - only pay attention to the NATIVE capacity of the tapes.

 

[n2nuk]

I understand what you are saying, but this is what I've got to play with, plus am working for a charity where funding is always an issue.

I have talked my boss into a 400GB LTO drive, but it wont be long before we hit the limits on this.

Thanks for the comments.

 

[k3n85]

I agree with 'lwcomputing' in that I've never seen a 2:1 compression, either software or hardware, and depends on the type of data in which you backup. I've noticed that backups of Mac OS X don't seem to compress as well, along with all of our software backups (ISO images pretty much already compressed). For jobs over 250 gb I have 2 tapes just incase.

 

[steevej]

Use compression ONLY if you must ($20 buck is cheap for 200Gb tape) see - Ebay)
We have found that using compression of data to the tape takes alot longer to backup, and alot longer to restore due to the mathematical overhead required for that feature - and it isn't reliable. The data is just packed too tightly together, which leads to eventual bit-migration across the surface of the media and data loss.

Our motto: "Use it if you can afford to lose it"

Buy a bunch of additional tapes and be safe ;-)

 

[cabraun]

I am able to get anywhere from 200GB to 600GB on an LTO2 tape, depending on what is being backed up. I have seen as high as 900GB on a single LTO2 tape.

Databases (exchange, sql, oracle etc) don't typically compress well. I see the most compression on servers where I really am just backing up the file system.

We are going to LTO4 in the next few weeks. If anyone has any experience that they would like to share regarding compression ratios with LTO4, I would love to hear them.

 

[mofusjtf]

You could always explore a D2D backup option? Native capacity of SATA HD's is at 1 TB. And no expsnive tape drive to purchase. No SCSI cards to purchase.

Check out CRU-Data Port. They have some interesting hot swap USB hard drive solutions that might work a little better than your tapes and take the whole compression issue out of the equation. The speed is good too because they are USB 2.0.