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Two Different SSD brands on the same Mac Pro

M

Macquero

macrumors newbie
Original poster
Jun 26, 2012
15
0
Venezuela
Hi Guys, I have a Mac Pro Quad Core 2.8 GHZ Mid 2010. Currently I have a OWC Mercury 3G 120 GB SSD, I use this for applications. I was given another SSD but another brand, Intel 320 Series SSD, 120 GB, and I want to use it to run 2 virtual machines with Parallels: One with Windows 7 Ultimate and another with Windows XP. The questions are:
1. - The OWC SSD uses Sandforce, therefore, is not necessary to activate the function TRIM in Lion. If I install the Intel drive will I need to activate the TRIM function, if I do that, not affected the performance of my OWC SSD? Stay with the same useful life time?

2. - When I put the Windows Virtual Machine into the Intel SSD, is necessary to activate the TRIM function in them?

Thank you very much in advance for your help with this.
 
If you are good with a hex editor you can update the TRIM enabler to do INTELSSD instead of APPLESSD. Did it on mine and now I have TRIM on my old Intel and not on my OWC.
 
saulinpa said:
If you are good with a hex editor you can update the TRIM enabler to do INTELSSD instead of APPLESSD. Did it on mine and now I have TRIM on my old Intel and not on my OWC.
Click to expand...

Thank you for your answer Saulinpa. Did you know about a guide or article to make this?

Thank you in advance.
 
I think you will be just fine running the VM files off the SSD without TRIM. NIce to have a dedicated SSD for this.:D
If it seems to slow down for any reason look into TRIMing it otherwise enjoy.
 
derbothaus said:
I think you will be just fine running the VM files off the SSD without TRIM. NIce to have a dedicated SSD for this.:D
If it seems to slow down for any reason look into TRIMing it otherwise enjoy.
Click to expand...
Thank for your recommendation Derbothaus, I just did it, I Run the VM into the Intel SSD without TRIM enable, but I don't see any significant performance. The speed appears to be the same as in the previous disk (7200RPM), however, I Will continue to do some tests.
 
Garbage Collection

I personally don't agree with OWC on this point. I looked into this with Sandforce, and believe that OWC missed their point.


Here is a background on TRIM -

In flash memory, Garbage Collection (GC) is the process of relocating existing data, deleting stale data, and creating empty blocks for new data


All SSDs will have some form of GC – it is not an optional feature

NAND flash cannot directly overwrite a page with data; it has to be first erased

One full block of pages has to be erased, not just one page


GC starts after each page has been written one time


Valid data is consolidated and written into new blocks

Invalid (replaced) data is ignored and gets erased

Wear leveling mainly occurs during GC

The OS tracks what files are present and what logical blocks are holding the files

SSDs do not understand the file structure of an OS; they only track valid data locations reported by the OS

When the OS deletes a file, it marks the file’s space in its logical table as free - It does not tell the drive anything

When the OS writes a new file to the drive, it will eventually write to the previously used spaces in the table

An SSD only knows data is no longer needed when the OS tells it to write to an address that already contains data

How Trim Works -



The OS sends a TRIM command at the point of file deletion
The SSD marks the indicated locations as invalid data
TRIM Features:
► Prevents GC on invalid data
► Increases the free space known to the SSD controller



TRIM Benefits:
► Higher throughput – Faster host write speeds because less time writing for GC
► Improved endurance – Reduced writes to the flash

Lower write amplification – Less data rewritten and more free space is available • TRIM does not generally work behind a RAID environment


Sandforce has a patented technology called Durawrite. OWC believes that Durawrite is better than TRIM and makes TRIM obsolete. I don't agree. Sandforce does not agree, they recommend running Durawrite and TRIM.

Please see the attached chart from SandForce.


Screen%20Shot%202012-06-27%20at%203.44.18%20PM.png

Screen%20Shot%202012-06-27%20at%203.44.18%20PM.png
 

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topmike said:
I personally don't agree with OWC on this point. I looked into this with Sandforce, and believe that OWC missed their point.


Here is a background on TRIM -

In flash memory, Garbage Collection (GC) is the process of relocating existing data, deleting stale data, and creating empty blocks for new data


All SSDs will have some form of GC – it is not an optional feature

NAND flash cannot directly overwrite a page with data; it has to be first erased

One full block of pages has to be erased, not just one page


GC starts after each page has been written one time


Valid data is consolidated and written into new blocks

Invalid (replaced) data is ignored and gets erased

Wear leveling mainly occurs during GC

The OS tracks what files are present and what logical blocks are holding the files

SSDs do not understand the file structure of an OS; they only track valid data locations reported by the OS

When the OS deletes a file, it marks the file’s space in its logical table as free - It does not tell the drive anything

When the OS writes a new file to the drive, it will eventually write to the previously used spaces in the table

An SSD only knows data is no longer needed when the OS tells it to write to an address that already contains data

How Trim Works -



The OS sends a TRIM command at the point of file deletion
The SSD marks the indicated locations as invalid data
TRIM Features:
► Prevents GC on invalid data
► Increases the free space known to the SSD controller



TRIM Benefits:
► Higher throughput – Faster host write speeds because less time writing for GC
► Improved endurance – Reduced writes to the flash

Lower write amplification – Less data rewritten and more free space is available • TRIM does not generally work behind a RAID environment


Sandforce has a patented technology called Durawrite. OWC believes that Durawrite is better than TRIM and makes TRIM obsolete. I don't agree. Sandforce does not agree, they recommend running Durawrite and TRIM.

Please see the attached chart from SandForce.


Image
Image
Click to expand...

Thank you very much for your explanation TopMike, very useful and complete. So according to this diagram is recommended to enable TRIM option in OSX Lion, even if your SSD is based on SandForce (As is the case of my OWC)?
 
Macquero said:
Thank you very much for your explanation TopMike, very useful and complete. So according to this diagram is recommended to enable TRIM option in OSX Lion, even if your SSD is based on SandForce (As is the case of my OWC)?
Click to expand...


Yes - I enabled TRIM using the following software - http://www.cindori.se/en#3

I have a MacBook Air 2011 and purchased the OWC 6G 512 GB SSD. While this is not a Mac Pro, and not the same type of drive, I enabled it anyway.

Honestly I did not see a direct improvement, but I think the improvement comes when the drive gets close to full, or you are transferring in and out a lot of data. (i.e. copying movies, moving lots of files, you have a large Database, etc) -

Your results may vary, but in general apple uses TRIM by default on all Apple SSD's. If OWC recommends not using it, I think it is because they don't undersand GC, and have not really spoken to SandForce.

Good Luck!
 
topmike said:
Yes - I enabled TRIM using the following software - http://www.cindori.se/en#3

I have a MacBook Air 2011 and purchased the OWC 6G 512 GB SSD. While this is not a Mac Pro, and not the same type of drive, I enabled it anyway.

Honestly I did not see a direct improvement, but I think the improvement comes when the drive gets close to full, or you are transferring in and out a lot of data. (i.e. copying movies, moving lots of files, you have a large Database, etc) -

Your results may vary, but in general apple uses TRIM by default on all Apple SSD's. If OWC recommends not using it, I think it is because they don't undersand GC, and have not really spoken to SandForce.

Good Luck!
Click to expand...

Thanks Mike, I will follow your recommendations. One more thing, where I can download this software? Because in their website there is not a download link, or an indication that is available in the mac Appstore.
 
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