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Lucagfc
Jul 27, 2012, 05:47 AM
Hi

I' ve some problem with my Samsung 830 SSD after ML upgrade. When I installed the SSD 2 month ago the performance mesured with Blackmagic Disk Speed Test were: 380 MB/s write and 420 MB/s reading.

Now I' ve 350 write and only 180 Mb/S reading! anyone have this issue? thanks!



steve-p
Jul 27, 2012, 05:49 AM
Is it still indexing Spotlight in the background, or maybe something else is running that's reading and writing a lot?

Reason077
Jul 27, 2012, 05:49 AM
Make sure you have TRIM enabled. You need to re-enable it after installing Mountain Lion.

Lucagfc
Jul 27, 2012, 05:51 AM
Is it still indexing Spotlight in the background, or maybe something else is running that's reading and writing a lot?

Sppotlight is not indexing (no dot in the lenses in the top right cornet) and I' ve no other program running expect Mail, Safari and iTunes!

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Make sure you have TRIM enabled. You need to re-enable it after installing Mountain Lion.

I' ve never enabled TRIM for my Samsung 830. After some web search I decided to not use that because it' s not necessary

Reason077
Jul 27, 2012, 05:52 AM
I' ve never enabled TRIM for my Samsung 830. After some web search I decided to not use that because it' s not necessary

Sure, it's not necessary. But this is why you are seeing decreased performance over time.

Lucagfc
Jul 27, 2012, 06:04 AM
Sure, it's not necessary. But this is why you are seeing decreased performance over time.

I don't think that the disabled TRIM is the problem for me. disk has only 2 month and the benchmark with Blackmagic Disk Speed Test are really strange. The first test, now is good with 380 mb/s write and 430 mb/s read but after a couple of test the speed decrease to 200 mb/s and slowly increse at 300 but I don' t understand why! before ML installation after my last benchmark all works great.

Reason077
Jul 27, 2012, 06:06 AM
I don't think that the disabled TRIM is the problem for me. disk has only 2 month and the benchmark with Blackmagic Disk Speed Test are really strange. The first test, now is good with 380 mb/s write and 430 mb/s read but after a couple of test the speed decrease to 200 mb/s and slowly increse at 300 but I don' t understand why! before ML installation after my last benchmark all works great.

If you enable TRIM, you should get more consistent performance.

Lucagfc
Jul 27, 2012, 06:32 AM
If you enable TRIM, you should get more consistent performance.

Ok, but before ML installation all works great and with the TRIM disabled. Why in ML i need to enable TRIM to have the same performance of Lion?

AlexBass
Jul 27, 2012, 06:53 AM
Ok, but before ML installation all works great and with the TRIM disabled. Why in ML i need to enable TRIM to have the same performance of Lion?

Check to see if your data is encrypted, if so, decrypt it.
After installing ML, for some reason everything became encrypted slowing my Sammy SSD's down significantly.

If you can, get Windows for bootcamp and update the firmware, that usually does the trick.

As the others said, you should also try enabling TRIM.

Lucagfc
Jul 27, 2012, 07:47 AM
Check to see if your data is encrypted, if so, decrypt it.
After installing ML, for some reason everything became encrypted slowing my Sammy SSD's down significantly.

If you can, get Windows for bootcamp and update the firmware, that usually does the trick.

As the others said, you should also try enabling TRIM.

Do you mean FileVault? I check that and it's disabled. For me install Windows is not simple. Is not possible to install bootcamp on external disk so I need to resize my Samsung 256 Gb and I prefer to not do that.

I try to enable TRIM but the strange think is that the SSD performance change during the benchmark so in a really short time and It's a really strange thing!!

jeremiah239
Jul 27, 2012, 07:54 AM
This guy really doesn't understand what TRIM is.

Lucagfc
Jul 27, 2012, 07:59 AM
This guy really doesn't understand what TRIM is.

I kwow what TRIM is and I follow you advice and now TRIM in enabled but nothing changed. The performance drop after 2 or 3 read/write test are still there.

Reason077
Jul 27, 2012, 08:02 AM
Ok, but before ML installation all works great and with the TRIM disabled. Why in ML i need to enable TRIM to have the same performance of Lion?

There's no difference between SSD performance in Lion vs. Mountain Lion.

What you are probably seeing is reduced performance over time due to not using TRIM, and this might be particularly noticeable after installing a new OS, because OS installation means a huge number of files are getting deleted and new files being written.

See this article for a good explanation of how TRIM improves performance:

http://en.wikipedia.org/wiki/TRIM

Basically it comes down to this: Flash NAND cells must be erased before they can be written to, which takes time. Normally an SSD has no way to distinguish between blocks that contain live files and those which contain data that has already been deleted, so it can't erase the unused blocks straight away when you delete a file. That means when the OS writes a file to a block that has previously been used, the write will be slower.

What TRIM does is gives the OS a way to say "hey, this block has been deleted, you can go ahead and really erase it now".

While SSDs do contain mechanisms that work around the lack of TRIM somewhat (eg: garbage collection), it's better to enable TRIM if you can.

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I kwow what TRIM is and I follow you advice and now TRIM in enabled but nothing changed. The performance drop after 2 or 3 read/write test are still there.

You need to give it some time. TRIM may not have an immediate effect, but it should improve performance over time as files get deleted and unused blocks are TRIMed by the OS.

jeremiah239
Jul 27, 2012, 08:50 AM
There's no difference between SSD performance in Lion vs. Mountain Lion.

What you are probably seeing is reduced performance over time due to not using TRIM, and this might be particularly noticeable after installing a new OS, because OS installation means a huge number of files are getting deleted and new files being written.

See this article for a good explanation of how TRIM improves performance:

http://en.wikipedia.org/wiki/TRIM

Basically it comes down to this: Flash NAND cells must be erased before they can be written to, which takes time. Normally an SSD has no way to distinguish between blocks that contain live files and those which contain data that has already been deleted, so it can't erase the unused blocks straight away when you delete a file. That means when the OS writes a file to a block that has previously been used, the write will be slower.

What TRIM does is gives the OS a way to say "hey, this block has been deleted, you can go ahead and really erase it now".

While SSDs do contain mechanisms that work around the lack of TRIM somewhat (eg: garbage collection), it's better to enable TRIM if you can.

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You need to give it some time. TRIM may not have an immediate effect, but it should improve performance over time as files get deleted and unused blocks are TRIMed by the OS.

This

etsi
Jul 27, 2012, 09:06 AM
Is this method valid to enable trim again?

http://digitaldj.net/2011/07/21/trim-enabler-for-lion/

Lucagfc
Jul 27, 2012, 02:37 PM
There's no difference between SSD performance in Lion vs. Mountain Lion.

What you are probably seeing is reduced performance over time due to not using TRIM, and this might be particularly noticeable after installing a new OS, because OS installation means a huge number of files are getting deleted and new files being written.

See this article for a good explanation of how TRIM improves performance:

http://en.wikipedia.org/wiki/TRIM

Basically it comes down to this: Flash NAND cells must be erased before they can be written to, which takes time. Normally an SSD has no way to distinguish between blocks that contain live files and those which contain data that has already been deleted, so it can't erase the unused blocks straight away when you delete a file. That means when the OS writes a file to a block that has previously been used, the write will be slower.

What TRIM does is gives the OS a way to say "hey, this block has been deleted, you can go ahead and really erase it now".

While SSDs do contain mechanisms that work around the lack of TRIM somewhat (eg: garbage collection), it's better to enable TRIM if you can.

----------



You need to give it some time. TRIM may not have an immediate effect, but it should improve performance over time as files get deleted and unused blocks are TRIMed by the OS.

I really appreciate you post but I already knew the theory behind the TRIM.

My question is: The flash cell need to be erased before new write operation so the TRIM in theory should only influence write performance. But I have problems in reading performance. This in the really strange thing!

Reason077
Jul 30, 2012, 09:54 AM
Is this method valid to enable trim again?

http://digitaldj.net/2011/07/21/trim-enabler-for-lion/

Just use Trim Enabler from http://www.groths.org/?page_id=322

It's very easy to use and works with all recent OS X versions including Mountain Lion.

etsi
Jul 30, 2012, 09:56 AM
I had read in the past that this program replaces a system file instead of patching causing more trouble than good. Have they changed they way it enables trim?

Reason077
Jul 30, 2012, 10:06 AM
I had read in the past that this program replaces a system file instead of patching causing more trouble than good. Have they changed they way it enables trim?

Recent versions of Trim Enabler work by patching and thus are fine with all the various different OS X versions, including Mountain Lion.