Adaptec ASR-71605 RAID 6 Calculations.

[Ray Appleby]

I have built a 72TB RAID6 Array with 7 16TB drives on an ASR-71605 controller and it is working great. I have this controller installed on an MSI Z590 Gaming Carbon WiFi MOBO. I have had this installed for almost a year and I am very happy with the performance and stability of this controller.

It is my understanding that the controller handles the first parity calculation and the CPU handles the second calculation.

I have an MSI Ventus 3060 Ti with 4864 CUDA cores and I was wondering if there was a way to offload the second calculation (normally handled by the CPU) to the GPU?

If this is possible, will it improve the performance of a RAID 6 array?

 

[cesmith9999]

It is possible. it may help a tiny bit. not enough to make it worthwhile.

The device driver would have to be altered to add using the GPU for raid calculations. which is a niche area and will probably not happen.

here are real world example of using a GPU to power (software) RAID

Chris

 

[Sean Ho]

I've not heard of such a thing where the XOR parity is done by the hardware card but the second-order Solomon-Reed coding is done by the CPU; this does not make a lot of sense to me. Do you have a link or reference for further info on this?

In general, performance of RAID arrays has not been limited by parity computation speed since a long time ago. Your spinners will generally be the bottleneck.

 

[i386]

Your spinners will generally be the bottleneck.

Or suboptimal raid and filesystem settings

 

[Ray Appleby]

Thank you all for your responses! I appreciate you taking the time to reply.

I've not heard of such a thing where the XOR parity is done by the hardware card but the second-order Solomon-Reed coding is done by the CPU; this does not make a lot of sense to me. Do you have a link or reference for further info on this?

In general, performance of RAID arrays has not been limited by parity computation speed since a long time ago. Your spinners will generally be the bottleneck.

Thank you, Sean, but the math on this stuff is WAY over my head these days and I find the calculation of parity and how it is used to recover data is very complex. I do remember XOR calculations from my days at Ryerson working with registers in Assembly language on an IBM system 360 back in the 70's but that's about the limit of my understanding. As to the reference, I read an article which mentioned significant increase in CPU load with RAID6 because of the second calculation, but it may have been referring to software RAID6.

Further investigation indicates that the ASR-71605 supports Reed-Solomon RAID6 arrays. Does this mean that the hardware raid chip is doing both sets of calculations (which would render my query moot)?

I created this array using Build/Verify (I set the stripe size to 512K since NTFS writes data in a 512K block so I figured that it would be most efficient since the controller would write a single complete 512K block before moving to the next drive).

Can I assume that the RAID6 array that I created automatically uses the Reed-Solomon algorithm using the adapter for the second parity calculation?

Any further comments (or guidance) would be greatly appreciated.

 

[i386]

Does this mean that the hardware raid chip is doing both sets of calculations (which would render my query moot)?

Yes. This and more stuff (like encryptions etc on newer "smart" controllers).

since NTFS writes data in a 512K block

This is what I meant with suboptimal filesystem settings
What are you storing?
(Even for my entire UHD disc collections I use 64KByte sectors...)


Edit:

Can I assume that the RAID6 array that I created automatically uses the Reed-Solomon algorithm using the adapter for the second parity calculation?

Yes: What are the differences between the Adaptec RAID 6 and RAID 6 Reed-Solomon?

 

[Ray Appleby]

Yes. This and more stuff (like encryptions etc on newer "smart" controllers).

This is what I meant with suboptimal filesystem settings
What are you storing?
(Even for my entire UHD disc collections I use 64KByte sectors...)


Edit:

Yes: What are the differences between the Adaptec RAID 6 and RAID 6 Reed-Solomon?

Looks like I screwed up - when I changed the stripe to 512K from the default of 256K, I was thinking that NTFS was writing in 512K blocks but that number in my head should have been 512 BYTES! not Kbytes!! It took 2 days to do the build/verify and I have already transferred back about 40TB of my movies (which has taken several more days - transferring/moving from another computer in my local network (where I backed up my original 60TB RAID50 array before I added another drive and created the RAID6 array) using Robocopy at an average of about 100MB/sec over the Gigabit network) so I don't want to have to do it all over again unless I could expect to see a significant increase in performance. It seems to be working pretty well as it is - transferring from a local disk I'm getting approx 200MB/sec in real time writing to the array.

If I had done it properly, I suppose I would have been better off to have formatted at 64K per sector rather than the default 32K. For future reference, what would the best stripe size be for movie storage (everything from 720p DVDs to 4K UHD Blurays and 3D movies). I am using Kodi to organize the movies so there are also smaller (less than 64K) thumbnails of the actors but with 70TB I imagine that would not waste too much storage space.

 

[mobilenvidia]

Why are people so worried about speed of Arrays with data that doesn't change
A 100GB movie on a disk is written once, 64KB or in my case 1MB stripe size doesn't make any difference to speed
You only read the file as fast as the Movie Player needs to display it or your Network can shift it. (1Gb NIC = 112MB/s)
If you had 1,000,000x 512kb files being written 24/7 then stripe size will matter

in the end RAID 5 = one drive can fail
RAID 6 = 2x drives
Either case rebuild will take some time, usually limited to the ROC setting the rebuild speed at about 30% so can still perform normall functions at 70%
Its reading a lot of data to rebuild the missing data on one or more drives
GPU RAID woud be essential on NVMe arrays

I wouldn't bother with RAID 50 or 60, your still limited to 1GB NIC speed and rebuild will have to do a heap more work