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j-polasektamu.edu

Multiple backup streams from one network volume?

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Howdy,

 

Is there any way to setup multiple backup streams from a single Volume? We are consolidating Departmental Data from individual servers to a College NAS.  I have setup subvolumes from the NAS.  But I can only backup one sub volume at a time.  If it is not possible to backup multiple sub volumes at the same time,  any tips on increasing individual backup speed would be appreciated.

 

Thanks

 

Jeff Polasek

Sr IT Pro II

College of Engineering 

Texas A&M University

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jeff-p can setup multiple backup streams from different Subvolumes on the same NAS volume (which is what I think he wants to do) provided the following conditions are true: [1] He is in fact running a Server Edition of Retrospect Windows.  [2] He is backing up to a different locally-attached Backup Set for each Backup script—each on either a different disk drive or a different tape drive or a different Subvolume on the same disk drive.  [3] The NAS volume is locally attached to the "backup server" with a high-speed connection.

 

The basic idea is to run each two Backup scripts simultaneously in different "execution units".  I covered the procedure for Retrospect Mac 12.5 in December 2016, starting with this post and running through post #12 in that same thread.  There are only four pieces of additional information jeff-p needs to know: [A] an "activity thread" in Retrospect Mac is termed an "execution unit" in Retrospect Windows.  ["Bee"] jweisbin's desire in starting that thread was to simultaneously backup the same volume (there was no mention of Subvolumes, which are termed Favorite Folders in Retrospect Mac) to two different Backup Sets (which are termed Media Sets in Retrospect Mac)—one stored on-site and one to be stored off-site, so that thread veered off after post #12 in a direction that will not interest jeff-p—but my key feasibility experiment was in post #9 in that thread.  [C] My cheapskate license of Retrospect Mac is for the lowly Desktop Edition, which cannot officially run more than one "activity thread" simultaneously, so I had to resort to a kludgey workaround in posts #9 and 10 in that thread which has no relevance to any administrator running a Server Edition.  [D] Copy Media Set is the Retrospect Mac term for Transfer Snapshots.

 

In the above two paragraphs I have been talking about the feasibility conditions for running two different Backup scripts simultaneously; now I'll talk about the desirability conditions—i.e. whether the two scripts will execute simultaneously in less overall time than it would take jeff-p to run them sequentially.  My experiment showed that they would under certain conditions for a certain reason, both of which are covered in the fourth through last sentences in the second paragraph of post #12 in that thread.  Since I assume that the College of Engineering at Texas A & M is not rich enough to afford an SSD NAS ;), I therefore condensed those conditions to condition [3] in the first paragraph of this post.  However let me add a further desirability condition, which was not necessary in post #12 in that thread because jweisbin had definitely stated that his/her two Media Sets were going to be on two different physical volumes.  The further condition is that jeff-p, for condition [2] in the first paragraph of this post, should rule out having the Backup Sets on different Subvolumes of the same physical disk—because IMHO write-head movement between two Subvolumes would unacceptably slow down the simultaneously-executing scripts.  This means that the College of Engineering's Departmental Data, consolidated onto one NAS for operational purposes,  would have to end up de-consolidated onto a separate physical-disk (or tape) Backup Set for each Department.  I leave the political implications of that as a problem for jeff-p :).

Edited by DavidHertzberg
Un-bolded 1.5 paragraphs; the new Forums software bolded them after I put "[B]" (with or without the quotes) in front of them

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If the conditions for simultaneous backup of Subvolumes described in post #2 of this thread are unacceptable for jeff-p, let me offer a tried-and-true tip on increasing individual backup speed for sequential backup of Subvolumes.  The tip is to choose "No verification" for the Backup scripts, and then schedule separate Verification scripts for each of the two Backup Sets as described on pages 230-233 of the Retrospect Windows 12 User's Guide.  The advantage of this is that the Verification scripts will not interfere with use of the Departmental Data on the NAS—because Verification scripts compare the contents of Backup Sets to MD5 checksums stored in their Catalog Files, and can therefore be run during normal working hours instead of overnight.  The disadvantage is that, if jeff-p plans to take the Backup Sets off-site, that will have to be delayed until after the Verification scripts have run.

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In the second paragraph of post #2 in this thread, I should have included a fourth piece of additional information: [D] Copy Media Set is the Retrospect Mac term for Transfer Snapshots.  I will now modify the post to include that piece of information, but I think I should give jeff-p an explanation of why I conducted my test—described in post #9 of the thread linked to in the second paragraph of post #2 in this thread—using a Copy Media Set script instead of a Backup script.  

 

The reason is that I wanted the test to simulate the volume of what jweisbin wanted to do, but without doing multiple simultaneous Recycle backups of any of my three large-volume HDDs—the smallest-volume of which is located on a "client" machine and would therefore have to be backed over the LAN.  A single Recycle backup of the "client" machine took then, even specifying "No verification", over 2 hours. 

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In responding to another thread that involved Subvolumes, I noticed that page 444 of the Retrospect Windows 12 User's Guide says "Subvolumes are considered part of their parent volume when performing multiple executions.  For example, you cannot back up subvolumes belonging to the same volume concurrently. If you attempt to do so, Retrospect will back up the volumes consecutively." 

Therefore the approach I suggested in this post simply would not allow backups from multiple Subvolumes on the same disk Volume to overlap .  However the approach I suggested in this post is still perfectly OK; separate Verification scripts were added to Retrospect specifically in order to speedup individual client backups during an installation's "backup window" so that more clients can be backed up.

Sorry not to have checked the UG, and sorry if jeff-p—or anyone else—wasted time on the first approach I suggested.

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Hold on, jeff-p, the Retrospect developers must have heard you.

From the Release Notes for Retrospect Windows 12.6: "New: Support for concurrent backups from different subvolumes of the same source".

So the approach I suggested in this post would work if you upgraded to Retrospect Windows 12.6.  Go wild along with the other Aggies!

Edited by DavidHertzberg
Mentioned name for Texas A&M sports teams

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