I ran VTL on a different platform before and now run NFS on data domain.

The choice between VTL and NFS really comes down to cost.  As far as
happiness goes, I was a little happier with VTL due to the short volsers
compared to the long names of the file devices.  But not $50K happier (or
whatever the VTL license is)

Other differences are:

- ethernet vs fibre-channel  (We run on 10gbit cross-over connections, and
it's plenty fast)
- NFS does allow the concurrent read-access feature TSM has for the file
device class
- The datadomains have a maximum number of concurrent streams before it
starts queueing requests. (the number depends on the model) With a vtl,
you could just set the number of virtual tape drives to the number of
streams and it will queue in TSM instead of the data domain. This is more
of a hassle to deal with if you have multiple instances with no library
manager.  I don't know if this actually makes a real world difference, but
I prefer the idea of TSM queuing instead of the data domain for some
reason.
- You'll need to maintain a library manager with a VTL

I think as far as price/performance goes, NFS will be better and require
less management, although pure performance will show that VTL will be
faster and might be worth the extra cost for you.  (It wasn't for us)


PS, there is more discussion on this topic if you search the archive

Regards,
Shawn
________________________________________________
Shawn Drew




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[ADSM-L] Tape or NFS? (DataDomain specifically)






We've been told by consultants (these particular consultants shouldn't
throw stones) that DataDomain customers running TSM are far happier
running NFS than VTL, because DDRs are built primarily as file servers and
the VTL function is an add-on.

I can see the financial motive for staying with NFS (those VTL licenses
aren't cheap!), but I'm skeptical about the implication that there's a
functional or performance advantage to using NFS over VTL for a TSM
server, in our case on AIX.

Would anyone who's run both or chosen NFS care to comment? How much does
it depend on your infrastructure or your needs for LAN-free?

Thanks,
Nick


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