SATA SSD to ATAPI bridge in lower optical bay

[NoManIsland]

I have a 2008 Mac Pro (currently ko - see "Screwed up" thread), and I have OWC's Multimount mounting solution to put two SSDs in the lower optical bay: http://eshop.macsales.com/item/Other%20World%20Computing/MM352A52MP8/
I also have a Pioneer Blue-ray writer in the upper optical bay that I have connected to the ATAPI connection in the optical bay via an adapter:
http://www.newegg.com/Product/Product.aspx?Item=N82E16812240012
I have the two SSDs hooked up with SATA cables to the ODD SATA ports on the logic board, with a power splitter/adapter dividing the second optical bay power lead. I've been thinking of adding a third SSD to the lower optical bay using the ATAPI connection designed for the second optical drive (through the same type of adapter), and a SATA power splitter coming off one of the leads that power the existing two SSDs.

What I am wondering is if this could cause any power issues, and whether the ATAPI connection is going to be bottlenecking the SSD badly.

 

[SmilesLots]

SSDs use so little power that I think you could probably run 20 of them before you would have any power problems, if any at all. But speed through Atapi is definitely going to limit SSD performance IMHO. If you can, install a pci-x to sata/esata card, and you'll have your speed. You can get one for under $10.

 

[Transporteur]

What I am wondering is if this could cause any power issues, and whether the ATAPI connection is going to be bottlenecking the SSD badly.

PATA = 133MB/s (~100MB/s real life performance)
SATA = 300MB/s (~275MB/s real life performance)

Apparently the performance hit will be huge. Definitely not the way to go.
As already mentioned, a cheap SIL3132 based SATA card will give you the full performance. They won't be bootable, though.

 

[NoManIsland]

PATA = 133MB/s (~100MB/s real life performance)
SATA = 300MB/s (~275MB/s real life performance)

Apparently the performance hit will be huge. Definitely not the way to go.
As already mentioned, a cheap SIL3132 based SATA card will give you the full performance. They won't be bootable, though.

Thanks for the info, I suspected as much. It does bring up a question, however: my Blue-ray drive is a 12x writer, do you think that it is being bottlenecked as well? I'm really hoping to keep it hooked up to the ATAPI connection as I need the two ODD SATA ports for those two SSDs and don't want to fill a PCIe slot with a SATA card if I can avoid it.

 

[Transporteur]

Thanks for the info, I suspected as much. It does bring up a question, however: my Blue-ray drive is a 12x writer, do you think that it is being bottlenecked as well?

12x BluRay means a transfer rate of 54MB/s, so IDE is plenty fast for that.

 

[NoManIsland]

12x BluRay means a transfer rate of 54MB/s, so IDE is plenty fast for that.

That's great to hear, thanks. About the free ATAPI port in the optical bay, I understand that it is too slow for an SSD, but would it bottleneck a 2.5" SATA conventional HDD?

 

[Transporteur]

That's great to hear, thanks. About the free ATAPI port in the optical bay, I understand that it is too slow for an SSD, but would it bottleneck a 2.5" SATA conventional HDD?

Nope. Today's 2.5" drives don't reach speeds of 100MB/s, so you're good to go.

 

[jdiamond]

Atapi speeds...

PATA = 133MB/s (~100MB/s real life performance)
SATA = 300MB/s (~275MB/s real life performance)

Apparently the performance hit will be huge. Definitely not the way to go.
As already mentioned, a cheap SIL3132 based SATA card will give you the full performance. They won't be bootable, though.

Although ATAPI could be viewed as a class of PATA, it was not designed for hard drive use, and I don't believe it ever exceeded 33 MB/second, with most still at 16MB/sec. When I asked my local Apple repair about it, he said that the ATAPI in most Macs is definitely not faster than 33MB/sec.

If you find differently, please let me know.