MP 7,1 Running 4 SSD raid 0 in Mac Pro, I’m OK right?

[rondocap]

Running 4 SSD in 7.1 Mac Pro:

2 on sonnet fusion pcie card
1 on sata port
1 on usb internal port with sata adapter
(other sata has a 3.5)

has been working perfectly fine, apple raid 0 on all 4. No disconnects or odd behavior.

having said that, any potential pitfalls with combining this arrangement of ssds long term?

they’re being backed up via time machine to another drive too

 

[Juicy Box]

any potential pitfalls with combining this arrangement of ssds long term?

One being not having TRIM support due to the USB. Also, the speed would be negatively impacted with using USB.

(other sata has a 3.5)

Is this a 3.5" HDD?

I am unsure of the 7,1 set up, but maybe consider moving the 3.5" to USB, and put the SSD on the other SATA. This should increase the speed.

 

[mzeb]

Given that you're already split across multiple controllers I'm not sure moving the SSD from USB to SATA will help much assuming your USB to SATA converter supports SATA 6. It might improve access times but the difference between 5 and 6gbps for a single drive in a RAID won't be huge.

Hard agree on the TRIM support though. You will potentially see the USB drive degrade more quickly (though a lot of SSDs have built in maintenance software which has gotten pretty good these days). Allowing the OS to moderate the drive maintenance through TRIM might speed things up a little too but prolly not too much (haven't run a test like this though so now I'm curious...).

 

[rondocap]

One being not having TRIM support due to the USB. Also, the speed would be negatively impacted with using USB.


Is this a 3.5" HDD?

I am unsure of the 7,1 set up, but maybe consider moving the 3.5" to USB, and put the SSD on the other SATA. This should increase the speed.

The 3.5 doesn’t work with usb because of power requirement, but 2.5 does.

the pcie sonnet card also shows up as usb, only Sata is the one plugged in to the sata port

 

[Juicy Box]

Given that you're already split across multiple controllers I'm not sure moving the SSD from USB to SATA will help much assuming your USB to SATA converter supports SATA 6. It might improve access times but the difference between 5 and 6gbps for a single drive in a RAID won't be huge.

It may not be a huge increase, but I think it could make a significant difference in speed.

The reason being is that it isn't just going from 5Gbps to 6Gbps, it would be that x4, since each drive would be reduced to the slowest drive's speed.

So, it would be 5Gbpsx4 = 20Gbps to 6Gbpsx4 = 24Gbps, roughly a 20% increase. Real world would be slightly less, but still, if I think it would be worth considering.

 

[Juicy Box]

The 3.5 doesn’t work with usb because of power requirement, but 2.5 does.

I am unfamiliar with the 7,1, but is there no other way to get power? Why not go external?

 

[rpmurray]

With the RAID 0 the failure of one drive will cause the whole array to fail. But I'm sure you have a comprehensive backup plan and aren't just relying on time machine.

 

[timerickson]

Running RAID over multiple controllers as well as multiple disks means you’re increasing the risk of failure by the number of controllers as well as the number of drives. I personally wouldn’t ever do this, but to each their own.You should definitely setup an automated daily backup for the array.

 

[rondocap]

Running RAID over multiple controllers as well as multiple disks means you’re increasing the risk of failure by the number of controllers as well as the number of drives. I personally wouldn’t ever do this, but to each their own.You should definitely setup an automated daily backup for the array.

I think you are right, it certainly does work, but increases issues a little bit too much. May just keep everything on individual controllers and separate

 

[mzeb]

It may not be a huge increase, but I think it could make a significant difference in speed.

The reason being is that it isn't just going from 5Gbps to 6Gbps, it would be that x4, since each drive would be reduced to the slowest drive's speed.

So, it would be 5Gbpsx4 = 20Gbps to 6Gbpsx4 = 24Gbps, roughly a 20% increase. Real world would be slightly less, but still, if I think it would be worth considering.

Not sure about Apple RAID's implementation but it shouldn't work that way. The controller (or software in this case) should read from each individual disk at maximum speed and buffer for the slowest disk to catch up before completing the read operation (this is primarily what the RAID cache gets used for). Throttling disks to the slowest is not ideal because of cases where no data for a particular read is stored on the slowest disk. That said, I'm using the magic word "should" and hoping it is not implemented as you suggest. Do you know for sure Apple RAID is implemented this way?