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Does the Late 2009 iMac i7 have dual channel SATA II?

I know there is a 3Gb/s SATA2 connection to the internal HD and a separate 3G SATA connection to the optical drive. But are those two SATA connections on separate channels?


To clarify, I am wondering if I can get greater than 3G speeds in a late 2009 iMac by putting an SSD in the HDD slot and another SSD in the optical drive slot. If there are 2 channels, then I would have the theoretical capability of a 6G SSD if I put the two in a RAID configuration.


Thanks.

iMac, OS X Yosemite (10.10), Late 2009, 2.8GHz i7, 16GB RAM

Posted on Nov 13, 2015 11:00 PM

Reply
66 replies

Aug 13, 2017 5:54 AM in response to Switch900

Switch900, I read this conversation far enough to have bought two SSD Samsung 850 EVO 1T drives last night only to read further. My current SSD (INTEL SSDSC2BB480G4 480G) is full and thought a RAID 0 at 2T would give enough breathing room but wasn't sure how exactly you got Disk Utilities to run the RAID 0 or if El Capitan would handle this. It's actually been so long since my HHD failure that I can't remember the boot sequence that got the current SSD loaded. My 2T G Drive Time Machine (Fire Wire) served me well making that repair painless so I assume it was either firmware boot configuration or a factory disk in a bay I'll be removing that made it uneventful. Now after reading about the card failure I'm wondering if it was the graphic intense work that push your card to failure or if it was the card handling video from two drives delivering everyday life twice as fast. My hopes were the RAID 0 2T (Unopened $678) internal with my current 2T G Drive would be a good functioning match for the needed space with a speed bonus if I could get the RIAD 0 set up. Another option for space would be more external storage but that come at transfer speed limitation being I'm 100% off the cloud. Could you provide some guidance to the RAID 0 setup and your take on this investment to my Late 2009 iMac for space need. If your card had not failed or JDW1 had created a RAID 0 I'd have more to go on experientially so your best guidance would be appreciated.

Nov 14, 2015 2:32 PM in response to Switch900

Thank you for your reply.


Just to confirm, you are saying (1) You get 6Gb/s throughput based on 2 separate 3Gb/s channels in the late 2009 27" iMac, and (2) you confirmed that by putting one 500GB Samsung EVO 850 in the internal HDD slot and a second 500GB EVO in the Optical drive slot (presumably using an OWC optical drive bay adapter), the using software to RAID them into one fast 1TB volume, correct?


DId you also use the OWC thermal sensor for the EVO in the HDD slot (which keeps the iMac fans running at normal speed, no software hacks required)?

Nov 14, 2015 7:31 PM in response to JDW1

yes and it runs Sata 2 I install 2 SSD of 1 terabyte into my late iMac 2009 just like yours and i am getting some awesome speed I think you should do the same and put it in RAID 0 you would get this kind of speed if you use Samsung SSD 1 tera evo 850

look up correct you have to buy the thermal heat sensor cable in order for the fan not to speed up, I happen to so get 2 one terabyte ssd Samsung 850 evo I bought the 3.5 to 2.5 bracket for the hdd bay and the data doubler for the super drive to exchange the super drive for the ssd there is a video tutorial on how to change these component you just have to put the idea for a ssd component. I then use then bought a hdd case to put the hdd drive that I use to have in my iMac and use that as a time machine for weekly backup. You will get some awesome speed if you raid two of the same exact ssd they have to be exactly in order to get a perfect raid 0 click on the blue text above and it will take you to the video showing my iMac speed disk test

Nov 15, 2015 1:49 AM in response to Switch900

Thank you for your replies.


Yes, I am aware the late 2009 iMac has SATA II (which means 3Gb/s). But what I am asking is this:


Does the late 2009 iMac have DUAL CHANNEL SATA II?


In other words, is there a SATA II 3Gb/s channel for the internal HDD AND a separate 3Gb/s channel for the Optical Drive?


Why do I even ask this question? Because if the late 2009 iMac is only a SINGLE CHANNEL SATA II machine, then putting an SSD in the internal HDD slot and another SSD in the optical slot will NOT give you more throughput, seeing both slots share the same slow 3Gb/s SATA II channel.


HOWEVER, if the late 2009 iMac is indeed 2-channel SATA II, then in theory, putting 1 SSD in the HDD slot and a 2nd SSD in the optical slot would yield 3Gb/s + 3Gb/s = 6Gb/s speeds.


And so, since you apparently are putting two 1TB SSDs in a late 2009 iMac and putting them in a RAID 0 config, what are your Back Magic Speed Test results?


https://itunes.apple.com/us/app/blackmagic-disk-speed-test/id425264550


If you only get about 275GB/s to about 290GB/s speeds in the Black Magic app, then you are only getting SATA II 3Gb/s, and that would prove the late 2009 iMac has only a SINGLE CHANNEL SATA II line. But if you get something like 500GB/s in the speed test, then it proves that iMac is DUAL CHANNEL SATA II.


So you can please run the Black Magic speed test and post your results?


Thank you.

Nov 15, 2015 4:07 PM in response to Switch900

Yes, I am aware that in El Capitan we need something like SoftRaid to RAID 2 internal SSDs:


http://softraid.com/


Thank you for your screenshot. But I still look forward to seeing the screen shot of your Black Magic Disk Speed Test:


https://itunes.apple.com/us/app/blackmagic-disk-speed-test/id425264550?mt=12


It's free, fast, and easy to use, so please give it a try.


That speed test will determine if you get 3G (about 280MB/s) or 6G (about 500Gb/s) speeds in your RAID setup, which in turn tells us if the SATA II HDD channel is the same or separate from the SATA II Optical Disk channel.

Nov 15, 2015 6:56 PM in response to SeaPapp

Switch900 needs only run the Black Magic Speed Test on his dual, internal SSD setup to confirm. If he gets upwards of 500MB/s (sorry for the "500Gb/s" typo in my previous post), he's got true 6G throughput (which means the SATAII is indeed 2-channel), but if he gets only about 290MB/s, then you're absolutely right, Mike, and that means the Mac is only single channel SATAII.

Does the Late 2009 iMac i7 have dual channel SATA II?

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