[philipmarch]

If I want to stripe two 80 GB drives, but one of them is filled with data, do I need to move the data off first and then move it back after the striping? Or will it just 'combine' the two 80's into 160 with my data intact?

[CatOne]

Originally posted by philipmarch:
If I want to stripe two 80 GB drives, but one of them is filled with data, do I need to move the data off first and then move it back after the striping? Or will it just 'combine' the two 80's into 160 with my data intact?

Creating a stripe (RAID 0) will completely destroy the data on the drive. You must back up *all* your date, and the drive will effectively be "reformatted" and you will have to reinstall the OS from scratch.

Also note that with RAID 0 you have twice the chance (actually maybe more) of complete data loss... because if you lose one drive you lose all data on BOTH drives... it's not recoverable. So... if you're gonna run RAID 0, be diligent about your backups.

[l008com]

Will a two or 3 drive IDE Stripped RAID, with each drive on its own bus, show a significant disk performance gain using software raid?

[p.h..i...l....]

Originally posted by l008com:
Will a two or 3 drive IDE Stripped RAID, with each drive on its own bus, show a significant disk performance gain using software raid?

Here is a benchmark i took from German magazin �Mac Profiler�


Single @ ATA/100: Write 37,0 | Read 36,4

RAID 0 @ ATA/66: Write 50,0 | Read 48,2

RAID 0 @ ATA/100: Write 60,0 | Read 57,4

RAID 0 @ ATA/66+100: Write 59,7 | Read 56,3

RAID 1 @ ATA/66+100: Write 24,2 | Read 31,5


So best configuration would be both HDs at the ATA/100.... I dont think three drives is possible, at least not with Apples utility.



Also got one question: Is it possible to boot X from a RAID 0?

[l008com]

Why wouldn't you be able to do 3 drives?

[flyhigher]

Originally posted by p.h..i...l....:


Also got one question: Is it possible to boot X from a RAID 0?

I'd like to know, too. Has anyone booted OS X from a RAID 0? Apple's Disk Utility Help says, "In most cases, you cannot use RAID on the startup disk." So, in some cases, it can?

[flyhigher]

Ok, for anyone who's interested, I found an entire forum discussing Mac RAID:

http://www.macgurus.com/6/ubb.x?a=fr...367&f=93260488

[BrettOZ]

Another question - does it matter if the 2 drives you are trying to get Raid 0 from are different sizes? I have an ATA100 80GB & an ATA 120GB drive?? What performance if any is there doing it this way???

[Spliffdaddy]

Originally posted by BrettOZ:
Another question - does it matter if the 2 drives you are trying to get Raid 0 from are different sizes? I have an ATA100 80GB & an ATA 120GB drive?? What performance if any is there doing it this way???

It would work fine.
Not really much performance difference than using 2 identical drives. The 'slower' drive will impact the speed of the faster drive, but the speed difference between the two drives isn't enough to matter. Don't even worry about the ATA bus speed, since your drives won't use 1/3rd of the available bandwidth anyway. ATA33 would work just fine.

Bottom line,
You'll end up with 160GB of 'striped' storage and 40GB of extra unstriped space. All partitions used in a striped array must be of equal size, therefore you'll have the entire 80GB drive as half of the striped array and 80GB of the 120GB drive will be dedicated to the striped array, as well. The array will have one drive letter and will be treated by the OS exactly like any other partition. That will leave you a 40GB partition on the 120GB drive. You can use that as a 'normal' partition, just mount it and format it. It'll get its own drive letter.

Edited to add:

You want each drive in your array to be on a separate ATA channel. Do not configure them as master/slave on the same channel (cable). The controller cannot communicate with more than one device on the same channel at the same time.

-----------------------------------------------------------

to the earlier question.. using 3 drives on a striped array is pointless if you only have a 2-channel controller. Instead, add a ATA PCI card and you'll get at least 2 more ATA channels. Four drives (on their own channels) in a striped array is probably the limit. Anything more and you risk PCI bus saturation.

[Camelot]

Originally posted by BrettOZ:
Another question - does it matter if the 2 drives you are trying to get Raid 0 from are different sizes? I have an ATA100 80GB & an ATA 120GB drive?? What performance if any is there doing it this way???

Originally posted by Spliffdaddy:
It would work fine.
[snip]
Bottom line,
You'll end up with 160GB of 'striped' storage and 40GB of extra unstriped space.

BZZZZT!!

If you RAID an 80GB drive and a 120GB drive you get a 160GB drive period.

The other 40GB is completely inaccessible

You can use that as a 'normal' partition, just mount it and format it. It'll get its own drive letter.

Huh? Drive letter?? Are you sure you're working on Mac OS X and not Windows?

[Spliffdaddy]

I was speaking in a generic sense about 'software' RAID 0 striping.

On many occasions I have striped across disks of different capacities and never 'lost' any disk space. Unless OSX stops you from doing it, you can have a standard partition on the same drive as a striped partition. You can even stripe two partitions on the same disk - not that it would help.

I haven't tried it in OSX, but I don't know why it wouldn't work as I described.

Yeah, I was thinking of Windows when I mentioned 'drive letters'.

[Brass]

Originally posted by Camelot:
BZZZZT!!

If you RAID an 80GB drive and a 120GB drive you get a 160GB drive period.

The other 40GB is completely inaccessible

I don't know about Mac OS X, but using Disk Suite on Solaris, I can certainly do that without loosing disk space.

[Powaqqatsi]

Little question, I have a PowerBook. But is it possible to have a FireWire RAID ? With the 2 drives attached to eachother in a serial fashion?

Like this:

Code:
Computer-->HDone<-->HDtwo

[tooki]

Yes, you can do that in OS X.

tooki

[Powaqqatsi]

Originally posted by tooki:
Yes, you can do that in OS X.

tooki

thanks