Negotiated Link Speed only 1.5Gbps for 256GB SSD on 15" mid-2009 MBP?

The lastest sandisk extreme firmware (r211m) fixes this problem.

http://forums.sandisk.com/t5/SanDisk-Extreme-SSD/SanDisk-Extreme-SSD-Firmware-R2 11m-download-for-for-MacBook-and/td-p/285948

Csound1 you are confusing Gigabit/second and Gigabyte/second.

The Serial-ATA adapter can either be 1.5 Gigabits,3 or 6 gigabits/second.

The ssd drive speed is measured in megabytes/second.

So anywhere from 100 megabytes/sec to 510 megabytes/sec. would be around 800 megabits to 4.08 gigabits/second much, much faster then what a 3 gigabit Serial-ATA adapter can handle.

On your link to the post above his hard drive is pushing 1.536 gigabit/s write 1.664 read. Now some of the current top of the line can push 4 gigabit/s write and 4.1 gigabit/s read.

Powermacguy12 wrote:

Csound1 you are confusing Gigabit/second and Gigabyte/second.

The Serial-ATA adapter can either be 1.5 Gigabits,3 or 6 gigabits/second.

The ssd drive speed is measured in megabytes/second.

So anywhere from 100 megabytes/sec to 510 megabytes/sec. would be around 800 megabits to 4.08 gigabits/second much, much faster then what a 3 gigabit Serial-ATA adapter can handle.

On your link to the post above his hard drive is pushing 1.536 gigabit/s write 1.664 read. Now some of the current top of the line can push 4 gigabit/s write and 4.1 gigabit/s read.

No confusion, except maybe by you.

GB/s = GigaBytes

Gb/s = GigaBits

MB/s = MegaBytes

Mb/s = MegaBits

Now read my post again.

Powermacguy12 wrote:

On your link to the post above his hard drive is pushing 1.536 gigabit/s write 1.664 read.

Read again, that is the link speed, the drive speed is significantly lower.

Powermacguy12 wrote:

Now some of the current top of the line can push 4 gigabit/s write and 4.1 gigabit/s read.

I do not believe your figures, kindly post links to these drives that can achieve 4+ Gb/s

http://www.anandtech.com/show/6337/samsung-ssd-840-250gb-review/5

The Samsung SSD 840 can achieve around 520 Megabytes/ second so around 4.2 gigabits per second. So on a SATA2 connection it would max it out, here you would need a serial ata 3 in order to use the max speed possible.

Powermacguy12 wrote:

http://www.anandtech.com/show/6337/samsung-ssd-840-250gb-review/5

The Samsung SSD 840 can achieve around 520 Megabytes/ second so around 4.2 gigabits per second. So on a SATA2 connection it would max it out, here you would need a serial ata 3 in order to use the max speed possible.

Yes, this drive can saturate a 3Gb/s bus, but not often: if you read the article only 2 parameters exceed the 3Gb/s bus speed:

Sequential reads (431MB/s above) and writes (383MB/s below), all other transactions are below bus speed.

Csound1 wrote:

Powermacguy12 wrote:

Csound1 you are confusing Gigabit/second and Gigabyte/second.

The Serial-ATA adapter can either be 1.5 Gigabits,3 or 6 gigabits/second.

The ssd drive speed is measured in megabytes/second.

So anywhere from 100 megabytes/sec to 510 megabytes/sec. would be around 800 megabits to 4.08 gigabits/second much, much faster then what a 3 gigabit Serial-ATA adapter can handle.

On your link to the post above his hard drive is pushing 1.536 gigabit/s write 1.664 read. Now some of the current top of the line can push 4 gigabit/s write and 4.1 gigabit/s read.

No confusion, except maybe by you.

GB/s = GigaBytes

Gb/s = GigaBits

MB/s = MegaBytes

Mb/s = MegaBits

Now read my post again.

Yes, your terminology is correct, so we can agree that 8 Gigabit/sec = 1 GigaByte/sec

On your earlier post you wrote that

Csound1 wrote:

The SSD is capable of 0.1 to 0.6GB/s, the bus it is connected to is capable of 1.5 to 3.0GB/s. As the drive is much slower than the slowest speed the bus can manage there is no more to be had.

Check this link for some measurements of an SSD on a 3G connection, nothing faster than .5G.

You probably meant to say that the bus its connected to is capable of 1.5 to 3 Gb/s not GB/s.

So 0.1 to 0.6 GB/s is equal to roughly 0.8 Gb/s to 4.8 Gb/s. Which you are correct can be slower then the 1.5 gigabit connection of SATA I but some of it is faster then both 1 & 2, thus needing a SATA III connection to achieve the maximum data rate.

You also write that only a few are faster then the theoretical 3 gigabit bus which is true, but reality does not always equal theoretical speeds , the real world top speed of SATA II is around 2.75 Gigabits, so connecting it to a SATA III controller will be faster.

So for the way consumer SSDs are moving we are having problems near the theoretical max speed of SATA II, while getting near SATA III theoretical speeds will take some time but we will get there.

Why do you think a company like Fusion-IO has to use a pci-e card instead of SATA III, they are pushing 700,000+ IOPS read and write, far exceeding what SATA III could dream of handling, but these SSDs are larger then the 2.5" form factor and is what we will be using in the future for our computers. Thats why there are specifications like SATA 3.2 that can finally achieve 1 Gigabyte/second +. Thats what we are looking forward too.

Yes things are getting faster, as always, and yes under some conditions some drives may be better on a 6Gb/s bus, not an issue to the majority of users yet.

I won't speculate on unreleased technology or what Fusion-IO were thinking.

This may help some people having trouble with the 1.5 Gigabit limitation on their SSD. It's what happened to me. I bouth OWC's 6G and now need to return it for the 3G, which will interestingly be faster on my old 5,3 model.

2008 MacBook Pro 15" (MacBookPro 5,1; 5,2; 5,3; 5,4; 5,5 and MacBook 5,1)

While a 6G SSD does function in a 2008 MacBook Pro 15" and 13" Macbook, it will only do so at SATA Revision 1.0 (1.5Gb/s) speeds rather that the SATA Revision 2.0 (3.0Gb/s) speed the machine can deliver. Should owners of these machines desire another SSD option, the Mercury Extreme Pro 3G SSD does run at the full SATA Revision 2.0 (3Gb/s) specification.

Found this on OWC's site. This may help some people having trouble with the 1.5 Gigabit limitation on their SSD. It's what happened to me. I bouth OWC's 6G and now need to return it for the 3G, which will interestingly be faster on my old 5,3 model.

2008 MacBook Pro 15" (MacBookPro 5,1; 5,2; 5,3; 5,4; 5,5 and MacBook 5,1)

While a 6G SSD does function in a 2008 MacBook Pro 15" and 13" Macbook, it will only do so at SATA Revision 1.0 (1.5Gb/s) speeds rather that the SATA Revision 2.0 (3.0Gb/s) speed the machine can deliver. Should owners of these machines desire another SSD option, the Mercury Extreme Pro 3G SSD does run at the full SATA Revision 2.0 (3Gb/s) specification.

I had similar problem with Intel 520 SSD, did this and it fixed the problem: http://support.apple.com/kb/HT3964

Hi Reza S, has the SMC reset consistently produced a link speed of 3G? I've installed the same drive and about 75% of the time I shut down and restart I get 3, but it is very unpredictable - wondering if you've got the same experience even after the SMC reset? Thanks!

Hi, I'm afraid I'm experiencing the same thing. It happens when you restart my computer. However, I use my mac with external monitor so I don't shut it down or restart it very often. Also, SMC reset fixes most of the time.

I solve the problem connecting my ssd to the dvd-cd bay on my mac mini,

the hdd bay is locked by apple.

i have a ssd 520 intel and its working.

Hi AlvaroW,

is your solution switching to the DVD sata is still working? is negotiated link speed 3GBps (Sata2) also after a regular reboot? or does it drop back to 1.5GBps?

i also have an intel 520 ssd and MCP89 controller (MacbookPro 7,1 mid 2010) and my negotiated link speed is always 1.5GBps (Sata1)

if your fix indeed works i will switch between the ports this evening...

Thanks!

Daniel.