Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

chrono1081

macrumors G3
Original poster
Jan 26, 2008
8,924
6,642
Isla Nublar
I was pricing a new mac pro and I saw the raid card option however if all I want to do is just mirror 2 drives would I need this? I know my laptop with my external raid enclosures I just use the OS to create the raid...am I missing something?
 
You don't need the RAID card for mirroring. You can do software mirroring with disk utility in OS X.

However the RAID card will be faster, but unless you have a specific requirement you probably don't need it.

I've run a RAID 1 and RAID 0 volume in my Mac Pro with the software OS X tools, it's fine.
 
You can do it through software thought it wouldn't be as fast as a hardware RAID. Just to know, the forthcoming Snow Leopard will introduce us to the ZFS file system which will do software RAIDs faster than any hardware controllers out there. Good article on it at ZDNet. Here's an excerpt:
No RAID cards or controllers
ZFS implements very fast RAID that fixes the performance knock-off against software RAID. In ZFS all writes are the fastest kind: full stripe writes. And the RAID is running on the fastest processor in your system (your Mac), rather than some 3-5 year old microcontroller.

Just add drives to your system and you have a fast RAID system. With Serial Attach SCSI and SATA drives you’ll pay for the drives (cheap and getting cheaper), cables and enclosures.

So it really sounds like going for the hardware RAID is a waste of alot of money unless you really can't wait another year.
 
Being CPU based is exactly the reason to use a RAID card. It uses your CPU all the time rather than letting the CPU get on with what it should be doing, your work.

Understood, but from the article it sounds like it'll offer the best RAID performance even with it taxing the CPU. Also -- for Mac Pro owners at least, with 8 cores now standard, the chances are you've got more than a few CPU cores to spare. To me it sounds like a great way to save $1000 on Apple's RAID card while getting even better performance.
 
Being CPU based is exactly the reason to use a RAID card. It uses your CPU all the time rather than letting the CPU get on with what it should be doing, your work.

This is mostly true. However, I have a RAID running off OSX in my G5 and I am almost never at 100% capacity with my cpus (the rare exception is, oddly, applications that don't use the RAID).
 
You also need Apple's RAID card (or a comparable 3rd-party solution) if you want to run SAS drives. But the vast majority of users (even a lot of pros) won't do this because of the significant difference in cost.
 
Yep

Understood, but from the article it sounds like it'll offer the best RAID performance even with it taxing the CPU. Also -- for Mac Pro owners at least, with 8 cores now standard, the chances are you've got more than a few CPU cores to spare. To me it sounds like a great way to save $1000 on Apple's RAID card while getting even better performance.

Exactly. Only a few users will need the extra RAID card and for them, price will probably not be an issue.
 
There is some 'processing speed' lost due to using software RAID, however, none of my applications take complete advantage of all four cores, so you wont notice much of a difference. I've also been told that you really only see software raid use your processors when reading/writing to the hard drives. Im not sure if this is true, but when im reading/writing files im usually either starting an application or saving files to the disk, and when this is being done, im not doing much else.

Though, I have to say, with the major advantage of the system being so quick when starting up and starting applications is very much worth the tradeoff for 'a little less' processing speeds from 4 cores (im on a mac pro 1,1)

I'm on two Western Digital Caviar drives, both with 250gb capacity, 7,200RPM and either 8mb or 16mb cache per drive (cant remember). I dont think it'd be easy going back to much slower startup times.
 
I just posted a new topic I guess on a related subject. I'm certainly not going to buy the raid card, but I'm wondering if RAID-1 causes reads or writes to slow down vs. single drive access when running software raid on the Mac Pro.

I have a lowly 4 core (early 2007) 3ghz machine, if that matters.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.