SSD Speed Comparison

[choreo]

I have two Macs, both with Samsung SSD Boot Drives:

MacPro 2012 3.33 GHz 6-Core Intel Xeon w/32 GB 133 HMHz DDR3 Ram
Velocity x2 PCI Card w/ two Samsung 500GB 840 EVO SSDs (one is boot drive with Mavericks 10.9.5)

MacbookPro 17" 2011 w/ Samsung 500GB 850 EVO

I just installed "Disk Sensei" on both machines to replace Trim Enabler and ran a couple benchmarks within that app on both machines. Can anyone tell me why the Powerbook appears to be so much faster than the MacPro? Launching Photoshop CC2015 on the older Powerbook takes 3 seconds. On the MacPro it takes about 10 seconds (for comparison). Is it because maybe the MacPro is SATA II and the Powerbook may be SATA III?

https://www.dropbox.com/s/n2322h6egtmva13/MacPro_Disk_Sensei.jpg?dl=0
https://www.dropbox.com/s/5kazc4h80xhtmsb/Powerbook_Disk_Sensei.jpg?dl=0

 

[Gav2k]

You hit the nail on the head. Your Mac Pro is sata 2 and the mbp is sata 3

 

[choreo]

You hit the nail on the head. Your Mac Pro is sata 2 and the mbp is sata 3

Thanks, that was all I could think of. There is such a big difference in the "latencies", that may be why apps are launching slower?

 

[SoyCapitanSoyCapitan]

Delete the caches in both library folders and try to test again. There should not be such a much difference between SATA 2 and 3 when launching apps. See benchmarks

http://www.tomshardware.co.uk/ssd-upgrade-sata-3gbps,review-32673-15.html

 

[choreo]

Delete the caches in both library folders and try to test again. There should not be such a much difference between SATA 2 and 3 when launching apps. See benchmarks

http://www.tomshardware.co.uk/ssd-upgrade-sata-3gbps,review-32673-15.html

Which caches?

 

[SoyCapitanSoyCapitan]

Which caches?

The application caches in library/caches and system/library/caches

Then you can check is the speed difference is the fault of RAM or something else

 

[choreo]

The application caches in library/caches and system/library/caches

Then you can check is the speed difference is the fault of RAM or something else

No significant change.

 

[SoyCapitanSoyCapitan]

No significant change.

You will just have to chalk it up to the operating system not performing identically on both platforms. It's not SATA or the SSDs unless the 840 has degraded.

 

[Inutopia]

On the MacPro it takes about 10 seconds

I think there's something wrong on the Mac Pro end. I just checked on mine and launching PS takes about 3 seconds.

Do you have heaps of plugins installed on the Mac Pro that aren't on the laptop? What about fonts? Check your font book, errors there can slow down PS with large font libraries.

 

[Thessman]

You hit the nail on the head. Your Mac Pro is sata 2 and the mbp is sata 3

The Velocity card is an adapter from PCI to SATA III, which depending on the exact model gives you about 800 MB/s max for both disks, not as much as 2xSATA III but much better than SATAII, so the reason for the delay should be something else. Do you have other PCI cards? which slot do you have your Velocity in?

 

[h9826790]

Is your 840 Evo using the latest firmware? There is a bug in the old firmware. Slow reading on old data (e.g. 3 months old).

The bug can reduce the 500MB/s reading speed to something like 25MB/s.

You may try to copy some old file (e.g. the photoshop app) from the 840 Evo to another disk (use a RAM disk as target disk can eliminate the target disk speed limit). And check if you are suffering from this bug.

 

[subsonix]

The Velocity card is an adapter from PCI to SATA III, which depending on the exact model gives you about 800 MB/s max for both disks

You are talking about two striped disks right? The theoretical max for SATA III is 600 MB/s after taking encoding into consideration.

 

[Thessman]

You are talking about two striped disks right? The theoretical max for SATA III is 600 MB/s after taking encoding into consideration.

No i'm talking 800 MB's total bandwidth, or 550 MB/s for one at a time, as is stated on the specs for the card, the solo x2 for example gives you two SATA III connectors, but the total usable bandwidth is up to 800 MB/s.

 

[subsonix]

No i'm talking 800 MB's total bandwidth, or 550 MB/s for one at a time, as is stated on the specs for the card, the solo x2 for example gives you two SATA III connectors, but the total usable bandwidth is up to 800 MB/s.

Right, but 800 MB/s implies that more than one SATA port is used, since you can not get more data out of the port than the spec of the SATA III protocol, no matter what the card says. SATA III provides 6 Gbit/s, i.e 750 MB/s, then the data is 8b/10b encoded, so each 10 bits carries 8 bits of data, so the theoretical max of SATA III is 750 * 0.8 = 600 MB/s.

 

[Thessman]

Right, but 800 MB/s implies that more than one SATA port is used, since you can not get more data out of the port than the spec of the SATA III protocol, no matter what the card says. SATA III provides 6 Gbit/s, i.e 750 MB/s, then the data is 8b/10b encoded, so each 10 bits carries 8 bits of data, so the theoretical max of SATA III is 750 * 0.8 = 600 MB/s.

You're correct of course, I just stated that it's a SATA III adapter (with a bandwidth equal to a real SATA III, give or take a few MB/s, as the actual sustained data rate of a SATA III ssd never exceeds 565 MB/s.) because Gav2k suggested that the SATA II interface of the Mac Pro is the culprit for the reduced performance of choreo's ssd.

 

[kennyman]

EDIT - wrong post