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Drives in SSD RAID - Speed to expect...

WardC

WardC

macrumors 68030
Original poster
Oct 17, 2007
2,727
215
Fort Worth, TX
Okay, I found a REALLY good deal on some 512GB SSD drives (They are Toshiba SSDs) on eBay, so I purchased 3 of them. I was thinking of putting them in my Mac Pro and RAIDing them together as a 3-drive SSD RAID. What kind of speed should I be expecting from a 3-drive SSD RAID versus using just one SSD? Will applications load even faster? Will it speed up things even more and make my Mac Pro more responsive? Or is it going to be just about like using the one SSD I am using now? I have a 3.33GHz 6-core Mac Pro, 12GB of RAM. I may purchase one more SSD and create a 4-drive SSD RAID if there is any real benefit speed-wise to this.

Thanks,
Ward
 
yeah I saw those on sale on ebay. are you running them in the mac pro bays and using software raid0?


two in raid0 should get 400mb/s 360Mb/s three in raid0 should get 600MB/s 540MB/s

note 3 of them would give you a 1.5tb ssd


you can put a 3tb western digital in the fourth bay as a superduper clone and use a fw800 2 bay as a time machine .


BTW how low did you get them 880?
 
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The performance gains from striped SSD arrays in terms of random performance (which is what speeds up the OS and application launches etc.) are if any minimal.

Sequential speeds apparently will be quite high (max 660MB/s, no matter how many SSD's you'll use), the OS itself doesn't benefit from this, though.

Depending on your work, the more sensible configuration would be a single OS disc and a two disc stripe for work data, such like scratch etc, although 512GB seems to be a waste as the scratch data will certainly never take that amount of data (1TB in this case).
 
Sustained speeds will improve but the ICH in Mac Pro maxes out at around 660MB/s. The Toshibas have maximum sustained read speed of 220MB/s and write speed of 180MB/s so theoretically you could get up to 660MB/s reads and 540MB/s writes. However, I don't know how well Toshibas work in RAID 0 and usually the performance increase is not as good as in theory. I would expect sustained speeds of 500-600MB/s.

Remember that random speeds don't benefit from RAID 0 so I don't think you're going to notice a huge difference in everyday tasks as it mainly consists of random reads. Big apps may open a bit faster and of course reading/writing big files will be but nothing revolutionary.
 
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Hellhammer said:
Sustained speeds will improve but the ICH in Mac Pro maxes out at around 660MB/s. The Toshibas have maximum sustained read speed of 220MB/s and write speed of 180MB/s so theoretically you could get up to 660MB/s reads and 540MB/s writes. However, I don't know how well Toshibas work in RAID 0 and usually the performance increase is not as good as in theory. I would expect sustained speeds of 500-600MB/s.

Remember that random speeds don't benefit from RAID 0 so I don't think you're going to notice a huge difference in everyday tasks as it mainly consists of random reads. Big apps may open a bit faster and of course reading/writing big files will be but nothing revolutionary.
Click to expand...

I'd be plenty happy with that !
 
I think I am going to put one of drives in my new MacBook Pro, and put the other two in my Mac Pro as a striped 1TB two-disk SSD RAID-0 array. My Icy Docks arrived from OWC today!!

In response to your question, I got the drives new for $970 each on eBay. I thought it was a good deal, considering Apple is selling the same Toshiba SSDs for $1399. These were pulls from new systems, and the seller had previously sold several of these drives. I think 1TB will be enough storage for my RAID, I have not touched the first 1TB of my 2TB hard disk RAID0 I currently have, only used about 500GB at one time. Mainly I use it as scratch, and for my iTunes library and movies. I am really looking forward to making my Mac Pro run more silently by replacing all the hard disks with SSDs, the hard disk RAID can be quite noisy when it makes random clicks every now and then. With SSDs, my whole system will run completely silent (except for the fans).

So, that is what I will do. I don't think I can afford another 512GB SSD right now, although it would be nice to put three in there.

I wonder if the OS will notice any speed improvements from running off the RAID instead of on one SSD. Basically, I wonder if boot times will improve even more, and if Applications will load any faster than they do currently with one SSD. I have a 3.33GHz 6-core Mac Pro Westmere with 12GB of RAM, 120GB OWC SSD.

Thanks
 
I'm sure you will notice an improvement in speed in launching big apps. Even with SSD's it's still one of the main bottlenecks in the system. However, you are into a region of diminishing returns. Boot times probably won't change much, I think once you have even a single SSD, the memory test as well as initializing hardware and networking take over as the most significant parts of booting.

Man it would be sweet to have 1TB of SSD storage. That's pure luxury right there! :cool:

I'm waiting for Intel Gen 3 drives using 25nm NAND in the hopes that prices will come down 50% or more and allow me to get 1TB of storage for what I hope will be around $1200. :D
 
I am also holding out for ssd's, I have used enough of them to know a pair of 600gb intel 3rd gen's in a raid0 as a 1.2tb boot/app/itunes drive in 1 optical bay would be really nice. pull the optical hdd and use both sata hookups.

then use the other bays with four 3tb western digital hdds for backups/storage. I would be set.
 
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