Virtual Tape

[vankley]

We're currently evaluating virtual tape products from various vendors like Sepaton, Maxxan, etc... This would be used on five AIX TSM 5.2 / 5.3 servers to reduce the reliance on physical tape and speed up backups and daily processes.



Does anyone have any experience with these products? Pros / Cons?

 

[AndyRH]

We are having a similar debate here. Except the TSM team is against a VTL, management is for the VTL. The TSM team is in favor of the same amount of storage being used for disk pools.

We can not think of a good reason for a VTL with TSM. The biggest negative seems to be virtual tape reclamation. Since we do not have one it is just a theory.

What is your reasoning for a VTL?



Andy

 

[vankley]

Well, since we have 5 TSM servers in one location, the reasoning goes like this:



Advantages of static disk pools:

- No reclamation



Disadvantage of static disk pools:

- They're static. I have to allocate as much storage as I think each server will need.





Advantages of VTL:

- Dynamic capacity (each TSM server only uses as much as it needs and that can change on a daily basis)

- Can do LAN-Free backups to VTL



Disadvantages of VTL:

- Reclamation (but it's all on disk, so how bad can it be?)





And, lastly, with TSM 5.3, they've introduced the ability to migrate inactive files from pool A to pool B (which means pool A only has active files)... This would allow you to keep your VTL only full of active files and migrate inactive files to real tape.



Yeah, I was tempted by the static disk pool idea, too... But the static nature of it doesn't work very well for me... If the VTL doesn't work out, that'll be my fall-back position.

 

[vankley]

Something else I just thought of....



If you use a sequential disk pool, you still have to run reclamation, don't you??



They (you know... "them") say that sequential disk pools would be faster than a normal disk pool... But nobody can quantify anything regarding TSM... It's always "better, worse, a little, somewhat, etc"...