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SSD speed on 2009 Mac Book Pro

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  SSD speed on 2009 Mac Book Pro Lewis <g.kreme@gmail.com.dontsendmecopies> - 2014-05-29 04:53 +0000
    Re: SSD speed on 2009 Mac Book Pro dempson@actrix.gen.nz (David Empson) - 2014-05-29 18:16 +1200
      Re: SSD speed on 2009 Mac Book Pro dempson@actrix.gen.nz (David Empson) - 2014-05-29 18:22 +1200
      Re: SSD speed on 2009 Mac Book Pro Lewis <g.kreme@gmail.com.dontsendmecopies> - 2014-05-30 04:28 +0000
        Re: SSD speed on 2009 Mac Book Pro billy@MIX.COM - 2014-05-30 22:52 +0000
    Re: SSD speed on 2009 Mac Book Pro Alan Browne <alan.browne@FreelunchVideotron.ca> - 2014-05-29 13:12 -0400
      Re: SSD speed on 2009 Mac Book Pro JF Mezei <jfmezei.spamnot@vaxination.ca> - 2014-05-29 16:00 -0400
        Re: SSD speed on 2009 Mac Book Pro Jolly Roger <jollyroger@pobox.com> - 2014-05-29 20:14 +0000
        Re: SSD speed on 2009 Mac Book Pro Your Name <YourName@YourISP.com> - 2014-05-30 09:03 +1200
          Re: SSD speed on 2009 Mac Book Pro Jolly Roger <jollyroger@pobox.com> - 2014-05-29 21:24 +0000
            Re: SSD speed on 2009 Mac Book Pro billy@MIX.COM - 2014-05-30 22:40 +0000
              Re: SSD speed on 2009 Mac Book Pro Jolly Roger <jollyroger@pobox.com> - 2014-05-30 22:49 +0000

#59822 — SSD speed on 2009 Mac Book Pro

I have an SSD in my 2009 MBP. When I run Black Magic the first write
test is quite decent, coming in around 170MB/s-225MB/s and the read test
is around 250MB/s. However, as the test continues to run the write speed
for the SSD drops dramatically, to the 20-35MB/s range and stays there.
Read speeds remain high.

This doesn't seem like it should drop like that.

The "Stress level" is set to 1GB and the machine has 8GB of RAM.

There's over 40GB of free space on the SSD.

So... ideas?

-- 
"Conservatives want live babies so they can raise them to be dead
soldiers" ~Carlin

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#59823

Lewis <g.kreme@gmail.com.dontsendmecopies> wrote:

> I have an SSD in my 2009 MBP. When I run Black Magic the first write
> test is quite decent, coming in around 170MB/s-225MB/s and the read test
> is around 250MB/s. However, as the test continues to run the write speed
> for the SSD drops dramatically, to the 20-35MB/s range and stays there.
> Read speeds remain high.
> 
> This doesn't seem like it should drop like that.
> 
> The "Stress level" is set to 1GB and the machine has 8GB of RAM.
> 
> There's over 40GB of free space on the SSD.
> 
> So... ideas?

I'd guess the SSD has a RAM-based write buffer, and writes to flash
memory in the background. Once you saturate the buffer you are limited
by the actual write speed of the flash memory in the SSD.

What brand/model is the SSD? There might be reviews online (e.g.
anandtech.com) which show expected performance and address this sort of
issue.

-- 
David Empson
dempson@actrix.gen.nz

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#59824

David Empson <dempson@actrix.gen.nz> wrote:

> Lewis <g.kreme@gmail.com.dontsendmecopies> wrote:
> 
> > I have an SSD in my 2009 MBP. When I run Black Magic the first write
> > test is quite decent, coming in around 170MB/s-225MB/s and the read test
> > is around 250MB/s. However, as the test continues to run the write speed
> > for the SSD drops dramatically, to the 20-35MB/s range and stays there.
> > Read speeds remain high.
> > 
> > This doesn't seem like it should drop like that.
> > 
> > The "Stress level" is set to 1GB and the machine has 8GB of RAM.
> > 
> > There's over 40GB of free space on the SSD.
> > 
> > So... ideas?
> 
> I'd guess the SSD has a RAM-based write buffer, and writes to flash
> memory in the background. Once you saturate the buffer you are limited
> by the actual write speed of the flash memory in the SSD.
> 
> What brand/model is the SSD? There might be reviews online (e.g.
> anandtech.com) which show expected performance and address this sort of
> issue.

A further thought: once all flash memory pages on the SSD have been
written, garbage collection needs to be done to shuffle other data
around to create more free pages, taking wear levelling into
consideration.

If the total amount of data written to the drive is in the order of its
capacity, you could be butting heads with the garbage collection and
wear levelling, limiting write throughput. If you stop write testing,
the SSD has some time to catch up on this process, so the next time you
run the test it already has a fair amount of free space.

-- 
David Empson
dempson@actrix.gen.nz

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#59841

In message <1lmf6aj.pclg9h1xpgg2qN%dempson@actrix.gen.nz> 
  David Empson <dempson@actrix.gen.nz> wrote:
> Lewis <g.kreme@gmail.com.dontsendmecopies> wrote:

>> I have an SSD in my 2009 MBP. When I run Black Magic the first write
>> test is quite decent, coming in around 170MB/s-225MB/s and the read test
>> is around 250MB/s. However, as the test continues to run the write speed
>> for the SSD drops dramatically, to the 20-35MB/s range and stays there.
>> Read speeds remain high.
>> 
>> This doesn't seem like it should drop like that.
>> 
>> The "Stress level" is set to 1GB and the machine has 8GB of RAM.
>> 
>> There's over 40GB of free space on the SSD.
>> 
>> So... ideas?

> I'd guess the SSD has a RAM-based write buffer, and writes to flash
> memory in the background. Once you saturate the buffer you are limited
> by the actual write speed of the flash memory in the SSD.

> What brand/model is the SSD? There might be reviews online (e.g.
> anandtech.com) which show expected performance and address this sort of
> issue.

Capacity:  240.06 GB (240,057,409,536 bytes)
Model:    Crucial_CT240M500SSD1                   
Revision:   MU03    

The M500s are generally rated quite decently, if not at the top tiers.

-- 
"You've got to dance like nobody's watching." - Kathy Mattea

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#59857

Lewis <g.kreme@gmail.com.dontsendmecopies> writes:

> Capacity:  240.06 GB (240,057,409,536 bytes)
> Model:    Crucial_CT240M500SSD1                   
> Revision:   MU03    
> 
> The M500s are generally rated quite decently, if not at the top tiers.

When the disk fills, it's going to slow down.  In the real world
of video editing, we have to leave some free space.  I don't know
if Black Magic's benchmark tool can be set to do this, but try
leaving 25% of the total capacity free.  Or, though it's not an
option here, use larger capacity drives, heh.

With this disk, enabling TRIM is a good idea.  For example -

https://digitaldj.net/blog/2011/11/17/trim-enabler-for-os-x-lion-mountain-lion-mavericks/

Billy Y..
-- 
        sub     #'9+1   ,r0             ; convert ascii byte
	add     #9.+1   ,r0             ; to an integer
	bcc     20$                     ; not a number

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#59828

On 2014.05.29, 00:53 , Lewis wrote:
> I have an SSD in my 2009 MBP. When I run Black Magic the first write
> test is quite decent, coming in around 170MB/s-225MB/s and the read test
> is around 250MB/s. However, as the test continues to run the write speed
> for the SSD drops dramatically, to the 20-35MB/s range and stays there.
> Read speeds remain high.
>
> This doesn't seem like it should drop like that.
>
> The "Stress level" is set to 1GB and the machine has 8GB of RAM.
>
> There's over 40GB of free space on the SSD.
>
> So... ideas?

I've noticed with hard disks that at the start, writing to an empty 
disk, the write rate is on the order of 165 - 185 MB /s (USB 3.0 / SATA 
III) but as the disk fills up, the write rate drops down to about 80 - 
90 MB/second at the end.  If the drive is encrypted, then it's a bit 
slower (about 20%).  (I posted actual numbers here about 3 months ago).

-- 
I was born a 1%er - I'm just more equal than the rest.

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#59830

Separate question on same subject:

If I buy an non-Aople SSD for my laptop and plug it in. Does OS-X
automatically behave any differently with regards to type of activity it
does on the disk ? (for instance, defragmenting the drive results in a
lot of writes).

If there needs to be some different handling of an SSD drive, what are
the commands to tell OS-X that the new drive should be handled as an SSD ?

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#59831

On 2014-05-29, JF Mezei <jfmezei.spamnot@vaxination.ca> wrote:
> Separate question on same subject:
>
> If I buy an non-Aople SSD for my laptop and plug it in. Does OS-X
> automatically behave any differently with regards to type of activity it
> does on the disk ? (for instance, defragmenting the drive results in a
> lot of writes).
>
> If there needs to be some different handling of an SSD drive, what are
> the commands to tell OS-X that the new drive should be handled as an SSD ?

Every non-Apple SSD I've ever installed in any Mac model just worked.
Why would anything special be required?

-- 
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR

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#59832

In article <538791d7$0$47879$c3e8da3$5d8fb80f@news.astraweb.com>, JF
Mezei <jfmezei.spamnot@vaxination.ca> wrote:
> 
> Separate question on same subject:
> 
> If I buy an non-Aople SSD for my laptop and plug it in. Does OS-X
> automatically behave any differently with regards to type of activity it
> does on the disk ? (for instance, defragmenting the drive results in a
> lot of writes).
> 
> If there needs to be some different handling of an SSD drive, what are
> the commands to tell OS-X that the new drive should be handled as an SSD ?

If you mean an internal SSD, then the drive will work like any other
type of drive ... except that the Trim* function doesn't work with
third-party drives, so you need to use an extra piece of software like
Trim Enabler or similar.

This might be the cause of the problems of the original poster as well.

* The ATA interface standard's TRIM command helps SSDs write faster
  and live longer.

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#59835

On 2014-05-29, Your Name <YourName@YourISP.com> wrote:
> In article <538791d7$0$47879$c3e8da3$5d8fb80f@news.astraweb.com>, JF
> Mezei <jfmezei.spamnot@vaxination.ca> wrote:
>> 
>> Separate question on same subject:
>> 
>> If I buy an non-Aople SSD for my laptop and plug it in. Does OS-X
>> automatically behave any differently with regards to type of activity it
>> does on the disk ? (for instance, defragmenting the drive results in a
>> lot of writes).
>> 
>> If there needs to be some different handling of an SSD drive, what are
>> the commands to tell OS-X that the new drive should be handled as an SSD ?
>
> If you mean an internal SSD, then the drive will work like any other
> type of drive ... except that the Trim* function doesn't work with
> third-party drives, so you need to use an extra piece of software like
> Trim Enabler or similar.
>
> This might be the cause of the problems of the original poster as well.
>
> * The ATA interface standard's TRIM command helps SSDs write faster
>   and live longer.

Meh. That blanket statement doesn't apply equally to all SSDs. Some SSDs
don't benefit from TRIM:

<http://blog.macsales.com/21641-with-an-owc-ssd-theres-no-need-for-trim>

-- 
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR

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#59855

Jolly Roger <jollyroger@pobox.com> writes:

> Meh. That blanket statement doesn't apply equally to all SSDs. Some SSDs
> don't benefit from TRIM:
> 
> <http://blog.macsales.com/21641-with-an-owc-ssd-theres-no-need-for-trim>

Scroll down to the end of this page and read my comment.  Heh.

Billy Y..
-- 
        sub     #'9+1   ,r0             ; convert ascii byte
	add     #9.+1   ,r0             ; to an integer
	bcc     20$                     ; not a number

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#59856

On 2014-05-30, billy@MIX.COM <billy@MIX.COM> wrote:
> Jolly Roger <jollyroger@pobox.com> writes:
>
>> Meh. That blanket statement doesn't apply equally to all SSDs. Some SSDs
>> don't benefit from TRIM:
>> 
>> <http://blog.macsales.com/21641-with-an-owc-ssd-theres-no-need-for-trim>
>
> Scroll down to the end of this page and read my comment.  Heh.

I read that, but didn't realize it was you! Good post. : )

-- 
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR

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