Offloading Speeds on Mac Pro with mTape to LTO-6..

[Tim Jones]

[Neil Sadwelkar] “BTW how did this data get into the Areca in the first place. If it copied this huge amount of data successfully, then the unit seems to be working fine.”

Actually, while that seems to make sense, it’s not a good measure of stability. When copying data to and from the filesystem, applications read and write data in chunks and the filesystem manager is caching even larger segments of data for burst writes and reads. Also, the low level drivers utilize memory management capabilities known as “scatter gather segmentation” to provide both improvements to observable performance and memory utilization. If you tracked actual drive I/O, you would see that this allows the drive to be quiesced for large periods relative to the actual application use. A quick test copying 300GB of data from one array to another at over 400MB/sec showed disk activity in the 42% average range (use cycle). This is the same mechanism that LTFS-based solutions use since they are running through the FUSE filesystem manager.

When BRU is reading data from the drives, we are using a much more direct API and there is no caching or scatter gather operations. Using BRU and reading that same 300GB of data from the array resulted in a disk use cycle of over 88%. This is also creating a much higher level of I/O stress on the RAID controller chipset. Combining these two heat generation situations will easily overdrive the Areca chipset’s heat profile limits. This is why simply adding a fan blowing over the cards resolved the crashes in our lab.

There is a very big difference in heat generation between 42% and 88% usage cycle for 8 spinning hard drives.

For the record, we have never seen these types of crashes / hangs with ATTO or HighPoint RAID HBAs or chipsets.

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

[Neil Sadwelkar]

Oh wow. That figures.

Thanks Tim for the detailed explanation.

So that means the OP is out of luck being able to use this RAID for LTO backup with Bru-PE, since the RAID has an Areca (Thunderbolt to) SAS RAID card built-in and cannot be separated from the drives.

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

[David Roth weiss]

When I was at Promax we always used two controller cards for every NAS system we would build that included an LTO, a RAID controller for the hard drives and a separate HBA controller for the LTO. Would that not solve the problems in this case?

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

[Tim Jones]

Hi David,

In this case, the Areca HBA is a separate controller. In our lab environment, the Areca fell over when it was ONLY used to control the DASD.

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

[Bob Zelin]

boy – I must be missing something here. I know that I am getting old – but……….

1) The Areca ARC-1880x, 1882x, 1883x does not work with HP Ultrium tape drives. BUT you are NOT working with these cards. You are working with an MLogic MTAPE with PreRoll Post on a Mac Pro cylinder – is that correct ? So you don’t need any host controller card – it’s inside the MTAPE. this plugs directly into the Thunderbolt buss on the Mac computer.

2) Your Areca disk drive array (ARC-8050T2) has the equivalent of an ARC-1883x inside it – this is completely independent, and should be on an independent buss on the Mac Pro Cylinder.

If you DISCONNECT your ARC-8050, and just try to use the MTape with PreRoll Post to backup anything (like a USB drive) – does this work ?

Bob Zelin

Bob Zelin
Rescue 1, Inc.
bobzelin@icloud.com

[Bob Zelin]

https://www.imagineproducts.com/index.php?main_page=product_info&cPath=9&products_id=53&zenid=f949efb8df0a55b2b2e225cbfcd996fa

If the price of the product I have listed above is too expensive, then I will have to kill you. Try this with your MTAPE, and let me know what happens.

Bob Zelin

Bob Zelin
Rescue 1, Inc.
bobzelin@icloud.com

[Tim Jones]

Hi Bob,

The issue isn’t the Areca-powered mTape unit. The Areca mTape firmware and OS X driver (it’s the combination) for that specific chipset has been tested and in fact, part of the Thunderbolt approval involved both Apple and Intel testing the unit with BRU PE. That unit works properly as we worked with mLogic and Areca to get it to where it is.

The frustrating result is that even though the Areca team now have the answer to the tape compatibility issue, they’re not expanding the changes to include their general population RAID HBAs.

They’re also apparently aware of the heat profile issues as it was their USA rep that recommended the fan solution to us 3 years ago.

I’m hoping that we hear more from Suny and his results with the new BRU PE build and using alternative source drives for the tests to fort her isolate the Areca array from the equation.

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

[Suny Behar]

First of all. THANK YOU all for your input, ideas and suggestions.

I have been sidetracked on a job, and have not been able to get back to the thorough testing I was hoping to yet. But plan on setting the next couple of days aside to do just that.

To answer a few questions: The ARECA RAID got filled with about 12TB of DPX files at a scanning facility that offloaded the DPX scans from their SAN to the ARECA RAID via a Thunderbolt connection between the ARECA RAID and a Fiber connected Mac Pro.

As has already been answered, the Controller card is built into the mTAPE. So currently I am dealing with essentially a hardware RAID controller inside the free standing Thunderbolt ARECA RAID, and a Thunderbolt controller card inside the mTape.

I have currently transferred around 4 TB to an external USB 3 drive in preparation for tests backing from that drive to the mTape while taking the ARECA RAID offline.

Right now I am testing: BRU PE, PreRoll Post, and YoyottaID LTFS.

Right before I got pulled away from this task, the last thing I did was try Yoyotta (since the 2 other systems would not let me get through 1 tape successfully- this was prior to receiving an update from the gentlemen at BRU).

I can report that YoyottaID did allow me to offload to the mTape from the ARECA RAID without any crashes (Martin thanks for the assistance!). However, the current offload speed seems quite unpredictable. All of my DPX frames are the same size : 55MB/frame. Yet, with verification turned on. One tape offloaded around 200GB/h, the next dropped down to 125GB/h, then the following was back up to 195GB/h…. but they did offload without hanging or crashing the system. I watched the tape and noticed it take several pauses, then restart itself. At one point, it even spit out the tape by itself, re-ingested it by itself, and kept offloading… All of this is probably adding to the erratic offload speeds.

I plan on trying these same files one more time with PreRollPost and the new build of BRU PE I got from Tolis and will report back.

[Simon Blackledge]

Surprised by this. Have 2 of the 8050T2 units and they have been great. The drives on the other hand! 🙂

How can an LTO6 mech pull data that a 900MBs+ raid can’t handle with ease ?

I know with Archiware P5 Backup the sw has a buffer. Do these apps not ?

Or is it that if you pull a steady streams from the 8050T2’s the raid card just overheats ? Surely thats not right :-/

So a Mac mini with an 8050T2 and an MTape daisy chained off the back of the 8050 is a no no ? And no manufacture is stating this compatibility issue?

[Tim Jones]

[Simon Blackledge] “Or is it that if you pull a steady streams from the 8050T2’s the raid card just overheats ? Surely thats not right :-/”

Unfortunately it’s right. But, it ONLY applies to the Areca HBAs / Chipsets. The HighPoint and ATTO HBAs do not suffer from the issue. There’s a reason the Areca cards are so must less expensive…

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