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RAID can't run osx x86?

chenjau

By chenjau,
in Hardware Components and Drivers

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nemattoad
nemattoad
Posted
Posted
Running RAID 0 is retarded anyway. VERY VERY minimal speed boost while doubling the chance of data loss.

 

I strongly suggest you google RAID 0 benchmarks. Especially with SATA or SCSI drives, RAID 0 provides close to double the read and write speeds. RAID 0 is an INGENIOUS idea for someone who does lots of I/O intensive tasks, video editing for example.

 

I believe it is retarded for a basic user who browses the net and checks emails only, but for ANY person who is computer savvy, they will notice the speed boost.

 

The doubling of data loss is true though, that is why it is advised to run a RAID 0+1 if you are dealing with important data, or store important files on the RAID and a seperate hard disk that is not in RAID.

 

As for RAID 0 not working in OS X86. This is correct. Remembering that the leaked osx86 was designed for ONE motherboard with a specific hardware configuration, you should go and study further on what motherboard RAID chips actually are. Unlike "TRUE" raid controllers, the ones that cost a few hundred bucks, any motherboard/cheap PCI card solution is NOT a hardware raid. This means that the RAID is done via driver and only the configuration and other minor tasks are done in hardware.

 

Well, what does all that mean. It means that a driver needs to be written for that OS that supports the RAID controller, which will actually be written more as a NON-RAID driver and just a IDE/SATA driver. Then, a second driver or a second segment of code would be needed to identify the disks on the controller and the type of RAID they are in. A third driver or code segment would then be needed to control the read/write of data to the controller and the mounting of the "RAID".

 

How this differs from hardware raid is that with a hardware raid, the OS sees one disk. The hardware raid controller handles all the RAID operations itself. The OS does NOT see multiple disks on teh controller and the OS has NO say in how the raid is done, it behaves as a single hard disk. If you have the ICH6R RAID or any other fake "hardware raid" and have linux installed, you will notice that with a RAID 0 of lets say 2 80GB drives, all teh driver will do is let you access these 2 drives, NOT the raid. You need a seperate driver called dmraid to mount these drives as a RAID 0.

 

In fact, if you have a REAL hardware RAID controller, OS X86 has a few hardware raid kernel extensions I believe, but whether they work is another story. The machine that this version of os x 86 is for did NOT use any form of raid, so logically it has no support for it.

snafu
snafu
Posted
Posted
thanks nemattoad,my mainboard is msi 875p with ICH5R ,I dont know is that true hardware raid?

and is there anyway to no-raid but keep data ? I'll do anyting to run macosx

on  my pc.thanks  :huh:

 

Chances are is that you have a software raid.

 

Once a raid is created (apart from a mirror) it can not be broken without data loss. The raid you are currently running is what is called a striped array, which means that the entire 'virtual' volume is spread amongst two or more drives. The only way to get the data off would be to.

 

1. backup your data and start again.

2. ghost (or some other disk cloning software) you striped array over to another single hard disk. but that would be pointless as i am sure that if you had another hard drive you wouldn't have this problem would you :D...

 

Hope this helps.

 

"TRUE" raid controllers, the ones that cost a few hundred bucks, any motherboard/cheap PCI card solution is NOT a hardware raid. This means that the RAID is done via driver and only the configuration and other minor tasks are done in hardware.

 

Even 'expensive' raid controllers such as a IBM 6i (Adaptec re-badge) require drivers in windows as windows does not have the required drivers built in for IO control.

nemattoad
nemattoad
Posted
Posted
Hope this helps.

Even 'expensive' raid controllers such as a IBM 6i (Adaptec re-badge) require drivers in windows  as windows does not have the required drivers built in for IO control.

 

 

As snafu said, many hardware RAID controllers still need drivers for the basic I/O. I did not mean to suggest otherwise in my post. However, I did suggest that you are much more likely to find support for hardware raid controllers in multiple OSs than software/fake RAID controllers because the driver is only doing basic disk I/O rather than RAID operations, resulting in a much simpler driver as all the serious stuff is done by the hardware on your controller.

 

Chenjau, your motherboard without a doubt uses a "fake" hardware RAID, meaning that if it was ever to work in OSX86, it would need a more complicated driver than a true hardware RAID. Since they are quite popular, it is not impossible that we will see an OSX86 driver and RAID mapper for these fake RAID controllers, namely the Intel's ICH5R, ICH6R, and ICH7R southbridge, and possibly others, but don't get your hopes up :(. Even in linux, a stable driver that supports Reading AND Writing to these types of RAIDs is fairly recent, within the last one or two years I believe.

 

Snafu's suggestion of ghosting/imaging your drive or backing up important data and restoring once the raid has been turned off is really the only way to go about it. You could also get another small hard drive and use that for OSX86 and leave your RAID alone, which is what I did.

DeathChill
DeathChill
Posted
Posted
I strongly suggest you google RAID 0 benchmarks. Especially with SATA or SCSI drives, RAID 0 provides close to double the read and write speeds.  RAID 0 is an INGENIOUS idea for someone who does lots of I/O intensive tasks, video editing for example.

 

Go look at RAID 0 benchmarks that show REAL WORLD performance. Synthetic tests don't prove anything. Far too lazy to look them up for you, but feh.

Xen0n
Xen0n
Posted
Posted
Go look at RAID 0 benchmarks that show REAL WORLD performance. Synthetic tests don't prove anything. Far too lazy to look them up for you, but feh.

 

Getting double the performance on a RAID 0 ATA or SATA array sounds like a stretch of the imagination to me. RAID 0 on a Fibre channel array with 6 or more spindles (more drives=better performace if you have the bandwidth) and 128mb of cache might get you that kind of performance. Most likely that isn't going to be on a desktop machine though.

 

I've been working with RAID for over 10 years and have never used RAID 0 on anything other than a test box. Why? Because I like my data... Having to rebuild my computer because Windows is f*cked up is one thing, but at least your data is pretty easily recoverable. With RAID 0 your data is striped across all drives... so losing even one is a big deal.

nemattoad
nemattoad
Posted
Posted
Go look at RAID 0 benchmarks that show REAL WORLD performance. Synthetic tests don't prove anything. Far too lazy to look them up for you, but feh.

 

Is my own RAID 0 "real world" enough for you. Writing files is close (75%) to twice as fast as with a single drive. Reading is most likely as fast but I dont have any good way to test that.

macgirl
macgirl
Posted
Posted
Is my own RAID 0 "real world" enough for you. Writing files is close (75%) to twice as fast as with a single drive. Reading is most likely as fast but I dont have any good way to test that.

 

I was able to set up a RAID0, here are some results from XBench to compare.

"Normal" IDE 7200 RPM ATA 133 UDMA:

Disk Test 55.45

Sequential 109.18

Uncached Write 91.51 56.18 MB/sec [4K blocks]

Uncached Write 96.95 54.85 MB/sec [256K blocks]

Uncached Read 161.22 47.18 MB/sec [4K blocks]

Uncached Read 108.81 54.68 MB/sec [256K blocks]

Random 37.16

Uncached Write 13.39 1.42 MB/sec [4K blocks]

Uncached Write 81.59 26.12 MB/sec [256K blocks]

Uncached Read 80.56 0.57 MB/sec [4K blocks]

Uncached Read 120.38 22.34 MB/sec [256K blocks]

 

RAID0 two IDE 7200RPM ATA 133 UDMA:

Disk Test 102.98

Sequential 189.11

Uncached Write 186.81 114.70 MB/sec [4K blocks]

Uncached Write 205.24 116.13 MB/sec [256K blocks]

Uncached Read 154.44 45.20 MB/sec [4K blocks]

Uncached Read 224.64 112.90 MB/sec [256K blocks]

Random 70.76

Uncached Write 33.35 3.53 MB/sec [4K blocks]

Uncached Write 130.51 41.78 MB/sec [256K blocks]

Uncached Read 84.71 0.60 MB/sec [4K blocks]

Uncached Read 141.18 26.20 MB/sec [256K blocks]

 

Make your own conclusions

 

What is a great deception is that doesn't boot.

macgirl
macgirl
Posted
Posted

First of all SATA only works from ICHx Intel or VIA Chipsets, if you have aone of these the raid is defined inside of Mac OS X and not directly in the BIOS, and again since the RAID is defined in DiskUtil it partitions the member disks with Apple Scheme instead of PC Scheme, so it wont boot.

 

For now RAID can be used as extra Volume, of course you can save all your data and programs there, but main OS files doesn't.

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