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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 (3038 Posts)

Virtualization, Cloud and Storage Architect. Tech Field delegate. VMUG IT Co-Founder and board member. VMware VMTN Moderator and vExpert 2010-18. Dell TechCenter Rockstar 2014-15. Microsoft MVP 2014-16. Veeam Vanguard 2015-18. Nutanix NTC 2014-18. PernixPro 2014-16. Several certifications including: VCDX-DCV, VCP-DCV/DT/Cloud, VCAP-DCA/DCD/CIA/CID/DTA/DTD, MCSA, MCSE, MCITP, CCA, NPP.