Hardware vs software RAID 0

[bn999]

Long time lurker, first time poster. I've never laid my hands on OSX so far. Last Apple I've used was the Lisa, a definite upgrade from the apple ][

Just order a 3.2GHZ MP yesterday w/base RAM & HD. I've also ordered lots of third party RAM and 4 X 64GB MTRON SATA SSD's. I want speed, not space.

My question is: Can anyone tell me if using Apple's RAID card could possible get me any more performance over software RAID 0? (please, no warnings of high risk - I know what I'm doing)

Also, what are the PROs or CONs to using either hardware or software RAID when it comes to booting OSX from RAID or using bootcamp for other OS's? I understand that bootcamp will not boot from any RAID partitions, but can it boot from 5th or 6th SATA drives while RAID volumes exist?

Any meaningful feedback appreciated.

 

[Rick Here]

It is my understanding that there is no windows driver support for the HW RAID card. If you boot from the 5th/6th drive and have boot camp there this should be fine, when in windows you will not see the RAID drives/volumes.
Please post your results for the HW RAID with solid state disks, this should be screamer.

 

[trainguy77]

The hardware RAID will keep all the work off the CPU. So this will keep your CPUs free to do other things. Thats the primary advantage however with that kind of CPU power would it really be worth it? Thats up to you. Also you will have to see if the 5th and 6th SATA ports(if they exist) work with windows as on the original mac pros it took some work to get drives to recognize in windows if it was connected to those ports.

 

[bn999]

The hardware RAID will keep all the work off the CPU. So this will keep your CPUs free to do other things. Thats the primary advantage however with that kind of CPU power would it really be worth it? Thats up to you.

For RAID levels other than 0 I would agree with you. But I am questioning whether RAID 0 benefits from hardware in the case of the MP. The only extra computation that needs to be done by the CPU is to determine which drive to read/write the stripe from/to - a simple math equation.


As to the sequential read/write speed, as long as there is no other bottleneck, it will be 480/360 MB/s with 0.1s latency. At least that is what can be achieved under Linux or Winblows. I guess if I don't see that speed, then I will have to try the card...

 

[Consultant]

Software raid = uses CPU
Cheap raid = uses CPU
High end raid = does not use CPU

Software raid = not recognized by other OS
Hardware raid = should be recognized by other OS with proper support

 

[diamond.g]

For RAID levels other than 0 I would agree with you. But I am questioning whether RAID 0 benefits from hardware in the case of the MP. The only extra computation that needs to be done by the CPU is to determine which drive to read/write the stripe from/to - a simple math equation.


As to the sequential read/write speed, as long as there is no other bottleneck, it will be 480/360 MB/s with 0.1s latency. At least that is what can be achieved under Linux or Winblows. I guess if I don't see that speed, then I will have to try the card...

The biggest positive for hardware RAID is the OS is presented the array as one disk. It doesn't realize there is more than one disk. This allows the RAID adapter to deal with bad sectors and the best way to write data and read data. In other RAID configs it also allows for the array to be rebuilt with less of a performance hit on the OS.

EDIT: and what Consultant said...

 

[mgsarch]

It is my understanding that there is no windows driver support for the HW RAID card. If you boot from the 5th/6th drive and have boot camp there this should be fine, when in windows you will not see the RAID drives/volumes.
Please post your results for the HW RAID with solid state disks, this should be screamer.

Is this true? I'm under the impression that when booting out of OSX you lose support for those 5th and 6th SATA interfaces?

p.s.
I'm jealous of the 4x64 SSD speed but man, that's a whole lot of money for a RAID array slightly larger than a raptor. Where is the real performance gain there? Bottleneck becomes what?

 

[kittiyut]

It is my understanding that there is no windows driver support for the HW RAID card. If you boot from the 5th/6th drive and have boot camp there this should be fine, when in windows you will not see the RAID drives/volumes.
Please post your results for the HW RAID with solid state disks, this should be screamer.

Not only you will NOT see the RAID, you will NOT be able to boot Windows off of the ODD as well. Think twice before getting the APPLE RAID card. See my post here: https://forums.macrumors.com/threads/456854/

 

[kittiyut]

Is this true? I'm under the impression that when booting out of OSX you lose support for those 5th and 6th SATA interfaces?

p.s.
I'm jealous of the 4x64 SSD speed but man, that's a whole lot of money for a RAID array slightly larger than a raptor. Where is the real performance gain there? Bottleneck becomes what?

Don't be jealous, you don't get a big "bang for buck" for using SSD in RAID
Remember that you also won't get full 64 GB of drive space. You'll lose even more doing 0+1 or RAID 5.