New Mac Pro & Thunderbolt software RAID

[michael_aos]

A while back I played with RAID-10 on 4x 3TB drives on a Late 2012 Mac Mini.

I was kind of surprised to find it was significantly SLOWER with 2x drives on Thunderbolt and 2x drives on USB3 than just having all 4 on USB3.

My question is with the new Mac Pro, if I have 2 individual Thunderbolt drives in software RAID 1, should they ideally be on the same Thunderbolt chain? Same Thunderbolt buss? Different busses?

In this case the drives are only capable of maybe ~150MB/s each, but I'd still like to know the "best" way to maximize performance.

 

[VirtualRain]

A while back I played with RAID-10 on 4x 3TB drives on a Late 2012 Mac Mini.

I was kind of surprised to find it was significantly SLOWER with 2x drives on Thunderbolt and 2x drives on USB3 than just having all 4 on USB3.

My question is with the new Mac Pro, if I have 2 individual Thunderbolt drives in software RAID 1, should they ideally be on the same Thunderbolt chain? Same Thunderbolt buss? Different busses?

In this case the drives are only capable of maybe ~150MB/s each, but I'd still like to know the "best" way to maximize performance.

I have no idea... Not sure who could possibly know this... I suspect you're going to have to take one for the team and try different setups and let us know

 

[ibgb]

A while back I played with RAID-10 on 4x 3TB drives on a Late 2012 Mac Mini.

I was kind of surprised to find it was significantly SLOWER with 2x drives on Thunderbolt and 2x drives on USB3 than just having all 4 on USB3.

My question is with the new Mac Pro, if I have 2 individual Thunderbolt drives in software RAID 1, should they ideally be on the same Thunderbolt chain? Same Thunderbolt buss? Different busses?

In this case the drives are only capable of maybe ~150MB/s each, but I'd still like to know the "best" way to maximize performance.

Look here: http://www.iozone.org/

You can run that, and it will tell you more than you want to know.

If you have Macports: sudo port install iozone

Then you can check out all kinds of disk io.

 

[michael_aos]

Real-world, I don't expect I'll see any difference in (mirrored) write speeds with any of the configs with these disks on the new Mac Pro.

I was thinking about it more from an architecture perspective.

Normally I'd do software mirroring across 2 different HBA's (Thunderbolt Bus), but I didn't know if in this case that might incur more overhead.

Anand's review mentions a PEX 8723 PCIe switch between the 3x Thunderbolt2 controllers and the CPU.

After re-reading his article, I don't think there's any penalty with having the disks on different Thunderbolt2 busses.
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[michael_aos]

This is what I'm thinking...

Port 1 (TB bus 1) - Apple Thunderbolt display (maybe 4K display eventually)
Port 2 (TB bus 2) - Apple Thunderbolt display (maybe 4K display eventually)
Port 3 (TB bus 1) - no connection
Port 4 (TB bus 2) - no connection
Port 5 (TB bus 0) - External storage
Port 6 (TB bus 0) - External storage
HDMI (TB bus 0) - Display
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