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RAID 0 on Mac Pro

ungraphic

ungraphic

macrumors 6502a
Original poster
Nov 15, 2007
596
0
Toronto, Canada
So I have some money to burn. And hard drives these days are relatively cheap for what you get, ie; 500gb HD for $95.

I'm currently on a 250gb WD Caviar 7,200 RPM 16mb buffer hard drive. Its pretty quick, i suppose. I can get another one of these for 65 bucks. Set it up for raid 0, increase speed, and gain space.

However, I would only use this for my startup disk, all other stuff like mp3s, movies, torrents, etc would be kept on another disk. So the 500gb total i would get, would go to waste.

I could of course, buy two smaller hard drives, but the 250gb HDs really are a good deal, and anything else doesnt offer the 16mb buffer. How does 8mb compare to 16mb? Any real difference? On single drives or in RAID? Also, Western Digital appears to have 'RAID Edition' hard drives.....would these be any better over a run of the mill hard drive?

Any suggestions?

Also, the RAID setup would be software based. Would overall performance, in say, running photoshop or quark be greatly hindered? I've got a Mac Pro Quad Core @ 2.66ghz. I've been told the only time where the processors are used is when applications or files are being read, or written, at which time, I wouldnt be doing any processing anyway. Can I get someone to verify this?

Thanks to all in advance :)
 
1. The main reason of RAID 0 (mirroring) is for data integrity in case of a HDD failure. Running that as your boot drive and not storing your data on it seems counter to the advantages of RAID 0. Boot drives you want speed (striped) or just a fast single drive (15000 RPM) since you can always reinstall the OS and applications. I'd put your RAID 0 setup for your data drive...data security is what it's for.

2. I have not noticed any slowdown using the Apple software RAID system. We have a fileserver running the file server drive off software RAID 0 in a small office and had no issues yet with speed. But it's a file drive, not an application drive.
 
Random Chaos said:
1. The main reason of RAID 0 (mirroring) is for data integrity in case of a HDD failure. Running that as your boot drive and not storing your data on it seems counter to the advantages of RAID 0. Boot drives you want speed (striped) or just a fast single drive (15000 RPM) since you can always reinstall the OS and applications. I'd put your RAID 0 setup for your data drive...data security is what it's for.

2. I have not noticed any slowdown using the Apple software RAID system. We have a fileserver running the file server drive off software RAID 0 in a small office and had no issues yet with speed. But it's a file drive, not an application drive.
Click to expand...

You've mistaken your RAID numbers. You are talking about RAID 1.
 
Isn't RAID 0 called striping and RAID 1 is mirroring? Striping is for speed and mirroring is for redundancy (backup).
 
ungraphic said:
So I have some money to burn. And hard drives these days are relatively cheap for what you get, ie; 500gb HD for $95.
Click to expand...

I used to run a RAID0 stripe "for speed" back when I ran a Windows desktop. Really, though, it didn't benchmark fast enough to justify the added complexity, risk, and cost. Sure, there are some synthetic benchmarks that can really highlight the benefits of striping, but for day-to-day operations I couldn't tell a bit of difference.

If you ask me (and you sort of did!) I think you'd be a lot better served by buying a second drive to use as a Time Machine backup of your data rather than chasing some marginal, theoretical speed boost you might eke out of a RAID0 stripe. I don't think you'll find the speed boost to be worth the hassle (especially if your data isn't even going to be on the striped volume).
 
Nugget said:
I used to run a RAID0 stripe "for speed" back when I ran a Windows desktop. Really, though, it didn't benchmark fast enough to justify the added complexity, risk, and cost. Sure, there are some synthetic benchmarks that can really highlight the benefits of striping, but for day-to-day operations I couldn't tell a bit of difference.

If you ask me (and you sort of did!) I think you'd be a lot better served by buying a second drive to use as a Time Machine backup of your data rather than chasing some marginal, theoretical speed boost you might eke out of a RAID0 stripe. I don't think you'll find the speed boost to be worth the hassle (especially if your data isn't even going to be on the striped volume).
Click to expand...

I have a 320gb external where i *very often* make backups of all my data. This hard drive is also constantly running as I have all my mp3s on it, but I dont want to have it running, I want it as backup only. With that said, time machine serves me no purpose. I have two internal on my current computer; 250gb WD for startup disk OS X, and a 200gb hd, partitioned for windows XP and a shared fat32 partition between windows and mac, which is about 140gb.

Ideally what I want is an internal that holds all of my music, movies and other random crap, along with a windows partition for bootcamp. And two drives under 320gb in RAID 0 for my startup disk for speed, which would include all my documents, psd files, etc.

I'd probably need a 400+ gb disk for the windows/mp3s drive.

Hmm.....i think i should just sell the 200gb, and buy a 400+gb and another 250gb drive anyway.
 
ungraphic said:
I have a 320gb external where i *very often* make backups of all my data. With that said, time machine serves me no purpose.
Click to expand...

If you're just periodically copying over the data then I think you're underestimating the value of Time Machine's ability to do "point in time" backups to allow you to recover files to exactly the state they were in at any arbitrary point in history. It really is a powerful model and represents a significant improvement over most of the ad hoc, manual backup procedures that people have come up with over time.

If you're using something more sophisticated like Retrospect then Time Machine isn't dramatically better -- although it's hard to put a value on its ease of use. The fact that you don't have to think about making a backup, it just happens (every hour) is a huge win for most people.

If all you're doing is Carbon Copy Cloner or dragging folders to the other drive then I think you're missing the real value of Time Machine.

And I think you're too optimistic about the speed gains you'd realize from doing RAID0. I don't think you'll find it's worth it.

You asked for people who had experience with it -- that was mine.
 
Nugget said:
You asked for people who had experience with it -- that was mine.
Click to expand...


Youre the first person to say its not a significant gain, with that in mind, it makes me want to do more research. I've been reading benchmarks where read and write times are nearly doubled with RAID 0, but i guess its something i should really digest as I use my internal hard drive differently.
 
ungraphic said:
Youre the first person to say its not a significant gain, with that in mind, it makes me want to do more research. I've been reading benchmarks where read and write times are nearly doubled with RAID 0, but i guess its something i should really digest as I use my internal hard drive differently.
Click to expand...

Not the first :)

AnandTech: RAID-0: Are two drives better than one?:
"If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer. The real world performance increases are negligible at best and the reduction in reliability, thanks to a halving of the mean time between failure, makes RAID-0 far from worth it on the desktop. Bottom line: RAID-0 arrays will win you just about any benchmark, but they'll deliver virtually nothing more than that for real world desktop performance. That's just the cold hard truth."

Storage Review: Single Drive vs Raid0:
What about performance? This, we suspect, is the primary reason why so many users doggedly pursue the RAID 0 "holy grail." This inevitably leads to dissapointment by those that notice little or no performance gain. Theory states that RAID 0 increases the sequential transfer rate, but how much does this really effect performance in contemporary desktop machines? As often indicated in StorageReview's forums, the answer is: Not much. STR simply does not significantly impact performance of typical desktop applications.

Computer Power User: To RAID or not to RAID:
Moreover, the actual performance boost that RAID 0 delivers often turns out to be considerably less impressive than expected, says Marty Czekalski, interface architecture initiatives manager at Maxtor and vice president of the SCSI Trade Association. “You will get a performance boost in RAID 0, but my own personal opinion is that the performance is not noticeable enough.”
 
Nugget said:
Not the first :)

AnandTech: RAID-0: Are two drives better than one?:
"If you haven't gotten the hint by now, we'll spell it out for you: there is no place, and no need for a RAID-0 array on a desktop computer. The real world performance increases are negligible at best and the reduction in reliability, thanks to a halving of the mean time between failure, makes RAID-0 far from worth it on the desktop. Bottom line: RAID-0 arrays will win you just about any benchmark, but they'll deliver virtually nothing more than that for real world desktop performance. That's just the cold hard truth."
Click to expand...

Thanks, that helps too now.....unfortunately :(

If thats the case, why are so many people boasting about SSD disks? The performance is about the same...theyre not *that* fast. Its not as if photoshop will load instantly after double clicking on its executable.
 
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