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View Full Version : Slow Disk Write speeds - MacBook Air 11" (2012)




BradClarke
May 16, 2013, 11:56 PM
I have a 2012 Macbook Air 11" 64GB, its only getting 150/MBs for write speed, and 390/MB/s for read speeds.

My main concern is the slow 150/MBs for write speeds, thats the highest it will go.

My older 13" 2011 Macbook air with 128GB ssd always gets 250/MBs for Read and write speeds.


Anyone know what the issue is?



opinio
May 18, 2013, 05:23 AM
I have a 2012 Macbook Air 11" 64GB, its only getting 150/MBs for write speed, and 390/MB/s for read speeds.

My main concern is the slow 150/MBs for write speeds, thats the highest it will go.

My older 13" 2011 Macbook air with 128GB ssd always gets 250/MBs for Read and write speeds.


Anyone know what the issue is?

Try disk repair in the recovery drive.

I always find a rebuild from scratch can help.

mseth
May 23, 2013, 06:12 PM
Are you using FireVault, it has a small impact on performance. It sounds to me like there is something else going on with your system. Try booting into Recovery Mode and repairing the disk & disk permissions.

dyn
May 25, 2013, 06:47 PM
The speeds are normal for the controller on the 128GB ssd. It probably is one from Toshiba which uses the Sandforce controller. Sandforce controllers will only reach the mentioned speeds when the data is easily compressed. When it is not the performance will be horrible. The tool you are using to test the disk speed is using data that is not easily compressed and thus it shows horrible speeds. However, like I said, these speeds are normal for that controller so nothing is wrong. If you want to upgrade then get a Samsung one. Do not use any from OWC since they use Sandforce controllers only and thus you'll have the exact same "problem".

peterson12
May 27, 2013, 08:11 AM
The speeds are normal for the controller on the 128GB ssd. It probably is one from Toshiba which uses the Sandforce controller. Sandforce controllers will only reach the mentioned speeds when the data is easily compressed. When it is not the performance will be horrible. The tool you are using to test the disk speed is using data that is not easily compressed and thus it shows horrible speeds. However, like I said, these speeds are normal for that controller so nothing is wrong. If you want to upgrade then get a Samsung one. Do not use any from OWC since they use Sandforce controllers only and thus you'll have the exact same "problem".

sandforce compression is relatively like windows search indexing. Data compression also enhances the NAND endurance and hence the overall performance of the SSD. Hence I am still ok if my ssd takes a while initially just to open up like a true power house in just a few hours time :)

dyn
May 28, 2013, 02:27 PM
That's what Sandforce wants you to believe. In reality almost any ssd has those kind of features minus the compressible data vs non-compressible data differentiation. The Sandforce controllers also consume more power than competitors. The Sandforce controllers work fine but there are better ones out there now for the same price or a bit cheaper now.

peterson12
May 30, 2013, 03:35 AM
That's what Sandforce wants you to believe. In reality almost any ssd has those kind of features minus the compressible data vs non-compressible data differentiation. The Sandforce controllers also consume more power than competitors. The Sandforce controllers work fine but there are better ones out there now for the same price or a bit cheaper now.

As you said Sandforce controllers works fine and it also flexible to all SSD's,When Writing to the NAND requires time and is usually the bottleneck of SSD performance. With data compression, less data is written to the NAND, and therefore, effective write
speed improves.Additionally, because fewer bits are written to the NAND as compared to an SSD that does not use data compression, the NAND is exercised less. This increases the relative endurance of the SSD, The unit features a Sandforce powered OWC Aura Pro 6G SSD, The unit is driven by a USB 3.0 interface that takes care of both data transfer and power; therefore, no external AC adapter is needed.

dyn
May 31, 2013, 01:33 PM
As you said Sandforce controllers works fine and it also flexible to all SSD's,When Writing to the NAND requires time and is usually the bottleneck of SSD performance. With data compression, less data is written to the NAND, and therefore, effective write
speed improves.

Speed doesn't improve. Other controllers apply no compression at all and are able to reach those speeds for both compressible and non-compressible data. Sandforce controllers will only be able to reach the advertised speeds with compressible data. As can be seen in real life tests and many benchmarks, the Sandforce controllers are not as fast as the competition.


Additionally, because fewer bits are written to the NAND as compared to an SSD that does not use data compression, the NAND is exercised less. This increases the relative endurance of the SSD,

If you implement data deduplication then there is much less writes to the NAND than with compressing data. The Sandforce controller was meant to make ssd's cheaper by enabling the use of NAND that can be written to much less than what was used thus far. We now know that NAND is able to sustain quite a lot (even TLC; the Dutch site hardware.info tested this). Problems with the controller are far more likely to occur and break an ssd. At the moment reliability and stability are bigger issues than NAND lifetime. The newest Intel ssd's are aiming at improving stability and reliability instead of speed or decreasing the amount of writes to NAND.


The unit features a Sandforce powered OWC Aura Pro 6G SSD, The unit is driven by a USB 3.0 interface that takes care of both data transfer and power; therefore, no external AC adapter is needed.
So? Buy any usb3 case that fits a 2.5" disk and you can fit whatever 2.5" disk you want being it an hdd or an ssd. There are some on this forum that already use a usb3 external case with their personal favourite ssd brand.

peterson12
Jun 6, 2013, 07:33 AM
Speed doesn't improve. Other controllers apply no compression at all and are able to reach those speeds for both compressible and non-compressible data. Sandforce controllers will only be able to reach the advertised speeds with compressible data. As can be seen in real life tests and many benchmarks, the Sandforce controllers are not as fast as the competition.


If you implement data deduplication then there is much less writes to the NAND than with compressing data. The Sandforce controller was meant to make ssd's cheaper by enabling the use of NAND that can be written to much less than what was used thus far. We now know that NAND is able to sustain quite a lot (even TLC; the Dutch site hardware.info tested this). Problems with the controller are far more likely to occur and break an ssd. At the moment reliability and stability are bigger issues than NAND lifetime. The newest Intel ssd's are aiming at improving stability and reliability instead of speed or decreasing the amount of writes to NAND.


So? Buy any usb3 case that fits a 2.5" disk and you can fit whatever 2.5" disk you want being it an hdd or an ssd. There are some on this forum that already use a usb3 external case with their personal favorite ssd brand.

I don't know your personal reason that heating towards SF, but true fact is controllers are designed specifically to make SSD and SF did efficient work here so what all leading companies got benefited by using SF controllers and they are ruling the industry,if you regularly updating with latest firmware then you really find the satisfied results. I am extremely glad that I have made a very smart decision in choosing Intel 520 SSD.

dyn
Jun 9, 2013, 10:07 AM
I don't know your personal reason that heating towards SF, but true fact is controllers are designed specifically to make SSD and SF did efficient work here 8<
What I'm trying to do is make you understand what you are saying and how ssd's in general work instead of repeating whatever marketeers tell you. The ssd's with a Sandforce controller work differently and it is this difference that explains the things the OP is seeing. What he is seeing is not a problem, it's a property of the Sandforce controller.

Your points are very weak because there is simply much more to it. For example, compression and encryption mean that either the cpu or the microcontroller on the ssd needs to do some calculations. This takes time and can affect speed (in either a positive or a negative way). When we look at the various reviews for different ssd's we can clearly see that the Sandforce controller has no big advantage over the competition. They are in the same range except for uncompressable data. It is what it is. It's just another controller, not something magical as you seem to believe. Nowadays almost any ssd will be good enough but there are quite a few that will be better.

peterson12
Jun 13, 2013, 09:30 AM
What I'm trying to do is make you understand what you are saying and how ssd's in general work instead of repeating whatever marketeers tell you. The ssd's with a Sandforce controller work differently and it is this difference that explains the things the OP is seeing. What he is seeing is not a problem, it's a property of the Sandforce controller.

Your points are very weak because there is simply much more to it. For example, compression and encryption mean that either the cpu or the microcontroller on the ssd needs to do some calculations. This takes time and can affect speed (in either a positive or a negative way). When we look at the various reviews for different ssd's we can clearly see that the Sandforce controller has no big advantage over the competition. They are in the same range except for uncompressable data. It is what it is. It's just another controller, not something magical as you seem to believe. Nowadays almost any ssd will be good enough but there are quite a few that will be better.


I appreciate what you are saying as well. I don't claim to know all the answers, but my information also comes from other sources.

This is an article on the latest Sandforce controller and their very low power draw. http://www.tweaktown.com/articles/5224/kingston-lsi-sandforce-b02-for-low-power-ssd-s-power-consumption-investigation/index.html

I also understand the compression issue, but it is not just a yes or no question. Most reviews I see do not ensure garbage collection is operating as is the case with your SSD 99.99% of its life. The reviewers grab the SSD out of the box and start testing. Any SSD is fast in that first day. It is after that time when the SSD will be performing at steady state. There were some detailed presentations at the Flash Memory Summit on these topics you might want to review.

Banchmarking - http://www.google.com/url?q=http://www.lsi.com/downloads/Public/Flash%2520Storage%2520Processors/LSI_PRS_FMS2009_F2A_Smith.pdf&usd=2&usg=ALhdy29XzBEyRXk3SqzG_yXHHRwvxwy47A

Compressibility and performance - http://www.lsi.com/downloads/Public/Flash%20Storage%20Processors/LSI_PRS_FMS2012_TE21_Smith.pdf