• Storage & Archiving

  BRU PE is forcing an archive of less than 2.5 TB onto two tapes

  Posted by Anthony Vieira on April 6, 2018 at 5:13 pm

  I’m backing up a client’s archive (7.5 TB total) onto a few tapes. I’ve whittled each backup folder down to less than 2.5 TB each. For the first time in the several years I’ve been using it, BRU PE is forcing me to make 2 volumes per archive. Has anyone else experienced this? The Tolis support is mostly useless, and I haven’t been able to identify this problem on other forums. Thanks!

  Tim Jones replied 7 years, 11 months ago 4 Members · 3 Replies
• 3 Replies

• 

  Neil Sadwelkar

  April 11, 2018 at 4:42 am

  An LTO-6 tape is capable of holding 2.5 TB, but Bru PE can write about 2.2 TB and not more. That’s because there’s an overhead for redundancy. This amount is variable depending on the number of files and their size.

  So, for instance, if I’m backing up Red raw files, I get to cram a bit more per tape than if I were backing up Arri raw. Because of the way these media is laid out. a 30sec clip in Red Raw is 5-6 files. The same clip in Arri raw is 720 odd files.
  But 7.5 TB worth of data no matter what the content, is not going to fit in 3 LTO-6 tapes whether you use Bru PE or any other software.

  I would advice making an archive of all 7.5 TB at one go, and let Bru make a set of 4 tapes. But if you must do the sorting yourself, I recommend making folders of 2.00 TB or less, and letting the data spread over 4 tapes.

  ———————————–
  Neil Sadwelkar
  neilsadwelkar.blogspot.com
  twitter: fcpguru
  FCP Editor, Edit systems consultant
  Mumbai India
• 

  Dean Tyson

  June 14, 2018 at 6:55 am

  I found that anything over the 2.4TB mark will be thrown to another tape.

  I struggled with an archive last week with the same issue.
  Archive total size was 2,594,067,199,868, which is around 2.3593TB.

  I originally had it sitting just on 2.5TB, but it was throwing the extra to another tape.
  I “trimmed” the archive and move a 45GB file to another archive and it all fitted to the one tape.

  This is the reason for me asking about using compression in a new post…
• 

  Tim Jones

  June 14, 2018 at 5:08 pm

  As we document many places, BRU’s reliability mechanisms – filesystem info, metadata, block-level CRC, error recovery info – consume approximately 18% extra space when writing to tape depending on data content, ACLs, extended Attributes, Finder Info, and other filesystem-specific data. This is why we provide the “How Many Tapes” button on the Backup panels. When you execute that pass, the result is taking into account the actual overhead that your specific data will require. And, with BRU, you don’t have to worry about data spanning tapes – BRU handles that automatically.

  Remember, in the grand scheme of things, tape is cheap compared to the time and cost of recreating lost data (if you even can). BRU’s container format is designed to provide the highest level of recoverability – because it’s the RESTORE that matters.

  Tim
  —
  Tim Jones
  CTO – TOLIS Group, Inc.
  https://www.tolisgroup.com
  BRU … because it’s the RESTORE that matters!

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