Mac Pro slow write speed on Samsung SSD drive

You would never get 540/250 on SATA II.

Using TRIM Enabler? booted from another drive and run Disk Repair?

Writes are of little real value for the boot drive with system high IO/sec and reads matter more.

Might want to look around for other utilities to find ones that give an accurate reading of performance of SSDs besides Disk Utility.

The 4 x SATA II drive bays all share a very limited common controller wtih max bandwith for all of less than 750MB/sec and each is not indepentent or 300MB/sec which even then would be 250MB/sec or slightly more.

Now, do you have a clone of the SSD you can also boot from on a traditional drive? only need that 250GB which is easy to find and create a partition for. Clone to that and boot from there and run DU Repair once it also has TRIM Enabler. And if you ever need to restore the system to the SSD. - I like to have a couple, one with last OS version, a backup before I install or update to next itteration of Mavericks. One that still has Lion or 10.8.5.

130MB/sec is within norms for 840's using Samsung Magician (Windows only, updates firmware, check performance and health of device).

A small change, small fee, but it 'paid off!'

One thing SSD does is forces having a system only (w/ apps) boot drive and all the data and media on other drives. A lot easier, quieter, with fewer drives and devices.

Your lower optical bay drives do NOT use the same shared SATA II bus controller, so they are their own. Your two could be their own scratch array or media library array or anything else.

I found iPhoto was bogged down by reading from and writing to the same drive which is always a slow process, putting any type of graphic library on its own SSD (works for Lightroom, Aperture very very well). \

No matter what or how well you optimized your 3,1 it would not do what nMP 6,1 will, maybe buy time is all for the inevitable. Even GPU's have a limited return on investment in terms of raw gpu power (that is where the 2010 shines with a pair of GPUs and better PCIe slots).

Thanks. Glad when things work out.

The hatter wrote:

...Your lower optical bay drives do NOT use the same shared SATA II bus controller, so they are their own...

Not to hijack the thread, but does that mean, in a fully populated Mac Pro, an additional SSD would benefit from being on the optical bay bus if it's the boot drive, or is bus bandwidth distribution different on 5,1 Mac Pros?

Our old ODD ports (call the first set #0 thru #3, these as #4 & 5) are separate. But applies to 1,1 thru 3,1 board design.

The 4,1 and 5,1 have no spare SATA ports and just the one lower optical bay which has different properties and limitations because it was meant for optical devices and for ejecting etc, but yes on a different bus and controller. But maybe not ideal bus for system to be on.

Thank you! That info has saved a lot of aggravation.😉

Regarding that lower optical bay on the 4,1 and 5,1 Mac Pros, I discovered a process chart of the Processor board in the Apple Technician Guide and the portion showing the South Bridge connections (p29). The SATA 3Gbps connection has 6 channels with 4 channels going to bays 1 through 4, each with 0.3GB/s bandwidth, and two channels going to the optical bay with each drive also getting its own 0.3GB/s bandwidth. The only difference appears to be that the channels going to the four bays are first connected to the SATA/SAS Mux (which, I imagine, ties a RAID card to the drives in the RAID array) and then get sent to the four bays and/or the fourth PCIe slot which also deals with RAID.

Is there something else I should be looking for as the downside of an SSD in the lower optical bay?

I don't see a downside, I have read great results from using it.

The "and each getting its own bandwidth" though is not true-ism.

with 2.5 SSDs you max out the limited, NOT 0.3Gb each, they are not independent is all.

And yes, 2009+ does not have the ODD type of the 1,1 - 3,1 models.