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SethR

Backup to LTO-6 Stalls Completely in Retrospect 12

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I have been struggling with a retrospect issue for about a month now. I am attempting to backup multiple drives to LTO6 tapes.

 

These drives are roughly 5 terabytes in size. The backup begins completely normal. It estimates roughly 18 hours for completion. 

 

I check back on it 8 hours later and the process has completely stalled out. It never stops. It never errors out. From first appearance, it looks like it is still working, but no files are transferring - no progress is being made. I can leave it for days and no progress is being made.

 

Even more annoying, it is near impossible to stop the process. Pressing stop on retrospect does nothing. Attempting to stop the server does nothing. I'm forced to reboot my entire computer and stop/restart the server - at which point the backup task is no longer even listed on retrospect as having failed or having been stop. It is just not listed at all.

 

Anyone know of any possible solutions?

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How much has been backed up during those 8 hours?

What if you monitor the progress every hours or (better) every 15 minutes?

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The amount varies. I've attempted this backup about 6 times now. On a 4 terabyte hard drive, it gets to about about 1.5-2.5 terabytes backed up before stalling out. It is never consistent.

 

I can try monitoring the process, but not sure if that will affect anything since it's getting stalled out at different points every time. No one is using the computer. I have been setting up the backups at the end of the work day and checking the next morning. The computer never enters sleep mode or is disrupted. 

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I see. It does do some real work before stalling. Then monitoring might not be the way go, since you never know when it happens.

 

What does Apple's System Activity say when Retrospect stalls?

How much CPU is the retrospect engine using? 

How much free RAM is there?

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I haven't checked the first two, but the computer has 4 gigabytes ram total. When it's stalled out, the harddrive I'm backing up from shows no activity nor does the tape deck I'm using.

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Just 4 gigabytes RAM? That isn't much.

 

In Apple's Activity Monitor, check how much free RAM there is after (say) an hours running.

 

How many files are there on the "source" drives? If there are over a million files, I say you need more RAM.

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Here is a screenshot of the computer when I came in this morning. Ran the process again, Retrospect is still stalling out. 

 

I could totally get behind the idea of the memory issue, as this machine being used for the backup is not just used only for that.

 

To explain my situation fully: I'm working on upgrading a collection of LTO3 tapes to LTO6 tapes. I'm having to use an LTO5 tape deck and an LTO6 tape deck as the LTO6 tape deck does not read LTO3 tapes. 

 

I have been working on a Mac Pro with 12 gigabytes RAM while doing restores from LTO3. The LTO5 drive is connected via an SAS cable.

 

The LTO6 drive via thunderbolt, which my Mac Pro tower does not have - so I have had to use a mac mini that my co-worker uses. I can't completely take over his computer, though, so he still is accessing the computer, working and doing such things as video editing, during the LTO6 backup process.

 

So basically, my setup:

LTO5 drive (restoring LTO3 tapes) -> SAS cable -> Mac Pro (12GB RAM)

LTO6 drive (backing up LTO6 tapes) -> Thunderbolt -> Mac Mini (4GB RAM)

 

Other Mac Mini stats: OS - Yosemite 10.10.5, Retrospect: 12.5.0

post-87747-0-87070800-1453836717_thumb.png

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Looking at the screen shot it says "Swap used 670 MB". That means you would need at least 670 MB more RAM at that instant. Since Retrospect is stalling, we don't really know how much more is needed to let it run.

 

I would at least double the RAM to 8 GB, preferably 16 GB. Any Mini from the mid 2010 model can take 16 GB.

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Trying to back up many TB using a relatively slow computer with only 4 GB of RAM that's also doing video processing at the same time seems like a recipe for trouble.

 

It sounds like what you're doing is restoring data from LTO-3 tapes to a hard drive volume, and then backing up that restored data to LTO-6 tapes. Is that correct? If so, how are you backing up the hard drive volume: via Retrospect client, or by connecting the hard drive directly to the Mac Mini?

 

That approach seems unnecessarily complex and time-consuming. A better approach would seem to be transferring data directly from your LTO-3 media set to the LTO-6 media set, which would require connecting the LTO-6 drive to your Mac Pro. You say you can't do that, which leads to two more questions: Assuming that your colleague's Mini isn't going to be the permanent backup computer, how and to what machine is the LTO-6 drive going to be connected in the future? The second question is, what kind of LTO-6 drive are you using that only has a built-in Thunderbolt link? All such external drives that I'm aware of have either FC or SAS, and would require an adapter for Thunderbolt.

 

Finally, regarding your screenshot, was that made while the stalled backup and the video processing were both running? Although the memory pressure indication would still be valid, the Retrospect console app is not what you want to be looking at; it's Retrospect Engine, which is a root, not a user, process.

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Trying to back up many TB using a relatively slow computer with only 4 GB of RAM that's also doing video processing at the same time seems like a recipe for trouble.

 

It sounds like what you're doing is restoring data from LTO-3 tapes to a hard drive volume, and then backing up that restored data to LTO-6 tapes. Is that correct? If so, how are you backing up the hard drive volume: via Retrospect client, or by connecting the hard drive directly to the Mac Mini?

 

That approach seems unnecessarily complex and time-consuming. A better approach would seem to be transferring data directly from your LTO-3 media set to the LTO-6 media set, which would require connecting the LTO-6 drive to your Mac Pro. You say you can't do that, which leads to two more questions: Assuming that your colleague's Mini isn't going to be the permanent backup computer, how and to what machine is the LTO-6 drive going to be connected in the future? The second question is, what kind of LTO-6 drive are you using that only has a built-in Thunderbolt link? All such external drives that I'm aware of have either FC or SAS, and would require an adapter for Thunderbolt.

 

Finally, regarding your screenshot, was that made while the stalled backup and the video processing were both running? Although the memory pressure indication would still be valid, the Retrospect console app is not what you want to be looking at; it's Retrospect Engine, which is a root, not a user, process.

 

 

The total workflow for this project is basically this:

 

Part 1:

 

LTO3 tape --inserted in--> Dell PowerVault LTO5 drive --connected via SAS cable--> Mac Pro (12GB ram) --sending data to--> USB 3.0 HDD docking station --containing--> hard drive (Seagate Archive HDD 8000GB)

 

Part 2:

 

Hard drive (Seagate Archive HDD) --mounted in--> USB 3.0 HDD Docking Station --connected to--> Mac Mini (2014 model containing 4GB ram) --exporting via Thunderbolt Cable to--> mLogic's mTape Thunderbolt LTO-6 drive --writing to--> LTO6 tape.

 

The end goal is to convert all of our LTO3 tapes (and eventually LTO4 tapes) to LTO6 while also having copies on hard drives as we plan on sending those hard drives off to be uploaded to a cloud service.

 

The LTO6 drive can only be connected via Thunderbolt. It has an SAS port, but that is only for connecting additional LTO6 drives for duplicate backups. 

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Mac Pro's does have Thunderbolt. Unless you have an old one. So, what do you have?

 

If you want to continue with your setup, you need more RAM in the Mini. But that isn't possible. So you need a new/used Mac with Thunderbolt and at least 8 GB of RAM. I would get 16 GB just to be sure.

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The Mac Pro is an early 2008.

 

I'm now looking into getting another system with more ram. Hopefully that clears up the problems. 

 

Thanks for all the help in getting this sorted out. I'm new to LTOs and to Retrospect so I've fairly quickly had to learn the systems and start informing co-workers about how they work.

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