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One curios thing of both ExaGrid and Dell DR4000 solutions (but also other solutions) is that they lack of a Virtual Tape Library (VTL) feature and only work as a network share (with CIFS or NFS). In both cases the reason was not technical (but I think that the main reason is still just a way to reduce cost and complexity) but marketing/strategy (customers just don’t ask at this feature). But moving from a backup to tape (B2T) to a backup to disk (B2D) solution does not necessary mean move to backup to file (over a share) solution.

All backup applications can  usually write to three targets:

  • Tape library (physical or VTL, but not all backup software support it)
  • NAS shares (network attached storage device share)
  • Disk volume (any local or SAN disk)

But some backup software may not work well (or not in a simple way) with a network share, compared to a VTL approach. And also a VTL can work over FC and iSCSI and permit to use the SAN or a “zoned” part of it as a backup area network.

Some product implement both the network share and the VTL methods… but also in this case seems that VTL is losing steam: for example the Data Domain guru Frank Slootman say “People think Data Domain is a VTL, but 90% of the systems we sell are IP-connected, not with a Fibre Channel protocol”.

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So is VTL really dead or close to be? Maybe not, because I know some customers that still need it and probably also for the next years… But VTL does not necessary mean better (or worst), faster (or slower) and cheaper.

For a scale-out architecture (like ExaGrid and DR4000) is not so easy implement a VTL solution because you may have several “head”… perfect for more parallelism in a network share, but not so easy to handled with a VTL. And for all solutions, a VTL mean of course more complexity: more interfaces (but this could simple mean new PCI-E cards), more software, space for virtual tapes (on some solution this mean that you need to pre-allocate this space, so less flexibility compared to a simple file solution), more complexity on how handle deduplication…

All those considerations can confirm that add a VTL feature to a B2D solution could mean more costs. Also from backup programs this could mean more costs: to have more parallel jobs (for example to handle a restore during a backup) you need more virtual drives… that could mean other licenses or options on your backup program.

Andrea MauroAbout Andrea Mauro (2310 Posts)

Virtualization & Cloud Architect. VMUG IT Co-Founder and board member. VMware VMTN Moderator and vExpert (2010, 2011, 2012, 2013, 2014, 2015). PernixPro 2014. Dell TechCenter Rockstar 2014. MVP 2014. Several certifications including: VCDX-DCV, VCP-DCV/DT/Cloud, VCAP-DCA/DCD/CIA/CID/DTA/DTD, MCSA, MCSE, MCITP, CCA, NPP.