HDD with similar read/write speed as an SSD = similar performance?

dprdoran

macrumors newbie
Original poster
Apr 21, 2017
3
0
Philadelphia
Hello,

I have a Mac Pro 1,1. (I know, time for an upgrade.) I have 2 dual core 2.33 processors and 16gb of RAM. I want to make my computer faster. I figured swapping out my boot hdd for an ssd would be a good option. After doing some research I realized that I am limited my the early Mac Pro's SATA II bus. So the two fastest hard drives I could find (that were not limited by my SATA II bus speed) are the:

OWC Mercury Electra 3G SSD (1TB for $387.85) Stated read/write speeds of 285/275 MB/s https://eshop.macsales.com/item/Other World Computing/ADPTA3G1TB/

and the

Seagate BarraCuda Pro SATA 6Gb/s with 256 cache(6TB for $245) Stated read/write speeds of 250/245 MB/s
https://www.amazon.com/dp/B01LOOJBH8/ref=twister_B01MFAITZ1?th=1

My question is, should an HDD with similar read/write speed as an SSD offer about the same performance? Am I missing something about the nature of an SSD that would still make it faster? Does anyone know if there is a better solution all together for my Mac Pro 1,1?

Thanks for all your help.

All the best,
Dan
 

AidenShaw

macrumors P6
Feb 8, 2003
18,085
4,147
The Peninsula
Hello,

I have a Mac Pro 1,1. (I know, time for an upgrade.) I have 2 dual core 2.33 processors and 16gb of RAM. I want to make my computer faster. I figured swapping out my boot hdd for an ssd would be a good option. After doing some research I realized that I am limited my the early Mac Pro's SATA II bus. So the two fastest hard drives I could find (that were not limited by my SATA II bus speed) are the:

OWC Mercury Electra 3G SSD (1TB for $387.85) Stated read/write speeds of 285/275 MB/s https://eshop.macsales.com/item/Other World Computing/ADPTA3G1TB/

and the

Seagate BarraCuda Pro SATA 6Gb/s with 256 cache(6TB for $245) Stated read/write speeds of 250/245 MB/s
https://www.amazon.com/dp/B01LOOJBH8/ref=twister_B01MFAITZ1?th=1

My question is, should an HDD with similar read/write speed as an SSD offer about the same performance? Am I missing something about the nature of an SSD that would still make it faster? Does anyone know if there is a better solution all together for my Mac Pro 1,1?

Thanks for all your help.

All the best,
Dan
Look at latency, not bandwidth.

It takes at least a handful of milliseconds for the spinner to move the head between tracks, and to wait for the desired part of the track to pass under the head.

During those milliseconds, the transfer rate is 0.

SSDs have no heads or moving parts, so jumping around the disk has no noticeable penalty for an SSD.
_______________

Also, large capacity HDDs are "banded". The outside tracks of the disk are longer, and have more data. That means higher bandwidth - more bits pass under the head per revolution.

The inside tracks are shorter (apply a little π logic) and have fewer bytes. Lower bandwidth.

It's not unusual for the outer tracks to have three times the bandwidth of the innermost tracks. Guess which number they put in the spec sheets ;)
___________

Also, don't limit yourself to SATA II SSDs. A SATA 3 (6 Gbps) drive will work fine in your system, and you might be able to find better deals ($ per GB) on the newer drives.
 
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dprdoran

macrumors newbie
Original poster
Apr 21, 2017
3
0
Philadelphia
Look at latency, not bandwidth.

It takes at least a handful of milliseconds for the spinner to move the head between tracks, and to wait for the desired part of the track to pass under the head.

During those milliseconds, the transfer rate is 0.

SSDs have no heads or moving parts, so jumping around the disk has no noticeable penalty for an SSD.
_______________

Also, large capacity HDDs are "banded". The outside tracks of the disk are longer, and have more data. That means higher bandwidth - more bits pass under the head per revolution.

The inside tracks are shorter (apply a little π logic) and have fewer bytes. Lower bandwidth.

It's not unusual for the outer tracks to have three times the bandwidth of the innermost tracks. Guess which number they put in the spec sheets ;)
___________

Also, don't limit yourself to SATA II SSDs. A SATA 3 (6 Gbps) drive will work fine in your system, and you might be able to find better deals ($ per GB) on the newer drives.
Thanks AidenShaw. I'm still trying to wrap my head around all the different things that can effect a computers speed/performance but I think I understand what you are pointing out. And thanks for the tip on checking out 6G SSD's as well. Might even be able to re-use it on a newer system one day!

Thanks for the help!
 

jbarley

macrumors 68040
Jul 1, 2006
3,772
1,615
Vancouver Island
I also have a MacPro1,1 and use 2 Samsung SataIII SSD's in a raid0 as my boot drive.
This gives access speeds very close to a Sata 6GB SSD as shown in the Black Magic result.
This is about the best I've managed to come up with so-far, but the search is never ending.
DiskSpeedTest.png
 

AidenShaw

macrumors P6
Feb 8, 2003
18,085
4,147
The Peninsula
I also have a MacPro1,1 and use 2 Samsung SataIII SSD's in a raid0 as my boot drive.
This gives access speeds very close to a Sata 6GB SSD as shown in the Black Magic result.
This is about the best I've managed to come up with so-far, but the search is never ending.
View attachment 697078
Note that for a boot drive, especially while booting, the system does lots of small IOs scattered across the disk.

No issue for an SSD, but much slower for a spinner because head delays are part of the test.

Black Magic, as you'd suspect, looks at the performance of reading and writing huge video files.

Is it at all surprising that a pair of 3 Gbps SSDs in RAID-0 "gives access speeds very close to a Sata 6Gbps SSD" on sequential accesses?

Not even Einstein would have guessed that 3*2 was about the same as 6. ;)
 

jbarley

macrumors 68040
Jul 1, 2006
3,772
1,615
Vancouver Island
Note that for a boot drive, especially while booting, the system does lots of small IOs scattered across the disk.

No issue for an SSD, but much slower for a spinner because head delays are part of the test.

Black Magic, as you'd suspect, looks at the performance of reading and writing huge video files.

Is it at all surprising that a pair of 3 Gbps SSDs in RAID-0 "gives access speeds very close to a Sata 6Gbps SSD" on sequential accesses?

Not even Einstein would have guessed that 3*2 was about the same as 6. ;)
Actually a pair of 3 Gbps SSD's did not give me the speed I was looking for,
it took a pair of SataIII 6GBPS SSD's to achieve that.
But I'm sure Einstein would have figured that out too, given enough time.
 

h9826790

macrumors G5
Apr 3, 2014
12,782
5,591
Hong Kong
Actually a pair of 3 Gbps SSD's did not give me the speed I was looking for,
it took a pair of SataIII 6GBPS SSD's to achieve that.
But I'm sure Einstein would have figured that out too, given enough time.
No matter how many SSD you RAID hen together. You can only improve the sequenctial speed, but not the random 4k speed.

If you want faster large copying speed. Then yes, RAID more SSD (or even HDD) can achieve it. But if you want faster system respond, RAID 0 basically won't help.
 

dprdoran

macrumors newbie
Original poster
Apr 21, 2017
3
0
Philadelphia
I also have a MacPro1,1 and use 2 Samsung SataIII SSD's in a raid0 as my boot drive.
This gives access speeds very close to a Sata 6GB SSD as shown in the Black Magic result.
This is about the best I've managed to come up with so-far, but the search is never ending.
View attachment 697078
Thanks jbarley. I like the idea of a raid 0 for some extra speed but I'll probably just keep it safe and simple with one. I'm curious, do you run an updated version of Mac OS? I know the 1,1 macs are 32bit and not able to run new versions of Mac OS without some creative fixes. I managed to get 10.10.2 up and running but I'm afraid to try and run updates. Wondering if you've had a similar experience.
 

jbarley

macrumors 68040
Jul 1, 2006
3,772
1,615
Vancouver Island
my MP1,1 is fully updated to 10.10.5, I used the "PikeYoseFix" script found in post#1 at this link.
Since downloading and installing the script (I chose the black boot screen) I've had zero issues with updates.

Screen Shot 2017-04-22 at 6.35.40 PM.png