MP 1,1-5,1 Understanding SSD vs HDD Sata II speeds

[Rv5]

Hey all, I'm just working on some upgrades for my 5,1 - so far been successful with USB 3.0, x2 cpu upgrade, 580 gfx and NVMe SSD.

One thing I can't quite figure out is the speed descrepency in the default bays. Though limited to Sata II speeds I was still expecting the SSD to be performing better.

Running 10.14.6
Using Black Magic Disk Speed Test
HDD (2 TB WD Extreme 7200rpm) : read and write both approx 170Mb/s
SSD (Samsung 840 250gb in APFS format) : write = 75Mb/s read = 140Mb/s
SSD (Samsung 840 250gb in Mac OS journaled format) : write = 40Mb/s read = 260Mb/s

while the NVMe is giving speeds more as expected: 14/1500 ish write and read

Would like to understand a little about the SSD results. Thanks for any insight!

 

[r6mile]

Hey all, I'm just working on some upgrades for my 5,1 - so far been successful with USB 3.0, x2 cpu upgrade, 580 gfx and NVMe SSD.

One thing I can't quite figure out is the speed descrepency in the default bays. Though limited to Sata II speeds I was still expecting the SSD to be performing better.

Running 10.14.6
Using Black Magic Disk Speed Test
HDD (2 TB WD Extreme 7200rpm) : read and write both approx 170Mb/s
SSD (Samsung 840 250gb in APFS format) : write = 75Mb/s read = 140Mb/s
SSD (Samsung 840 250gb in Mac OS journaled format) : write = 40Mb/s read = 260Mb/s

while the NVMe is giving speeds more as expected: 14/1500 ish write and read

Would like to understand a little about the SSD results. Thanks for any insight!

Have you looked at the 'negotiated' speed in the Hardware report under About my Mac? In the SATA section. It should be 3Gbps - anything lower (for example, I get 1.5 Gbps for one of my HDDs, which I need to diagnose properly) could indicate an issue with the SATA Bay, the connector, the drive, etc. You could also try swapping the drives between bays, if there is a particular one causing an issue, and seeing if you can narrow down the problem.

 

[KeesMacPro]

the samsung 840 evo should have a read/write speed in the SATA II bay's of around ~250-280 mb/s .
Could it be that there's no free space left on them?
Is TRIM enabled?

 

[Juicy Box]

I have a Mac Pro 1,1 and swapped drives many times over the years.

The HDDs sound realistic. I currently have two 4TB WD Red HDDs in a SW RAID0, and I get about 315MBps for Both Write and Read. Split that in half, and it is close to what you are getting.

I have had a few different SSD set ups in the Mac Pro 1,1 over the years, single and SW RAIDs.

Your SSD Write speeds are really slow. It makes me curious if you have TRIM enabled.

SSD (Samsung 840 250gb in APFS format) : write = 75Mb/s read = 140Mb/s

Both write and read are slower than what I would expect.

SSD (Samsung 840 250gb in Mac OS journaled format) : write = 40Mb/s read = 260Mb/s

The read speed is about what I would expect, maybe a little higher, but the write speed is really low.

I would check to see if you have TRIM enabled, and see if those drive are compatible with enabling TRIM.

 

[Rv5]

Hey guys, thanks for your replies. I tried out your suggeston @r6mile of swapping out the drives. Also checked the negotiated speed and it's 3Gbs

With SSD 1 and 2 in bays 1 and 2 (previously 3 and 4) and HDD in 3 (previously 2), read speed is now a more expected 250Mb/s in both (edit) but the write speed has lessed from 75 to 40ish in 1 and increased 40is to 60ish in 2. HDD is similar as it was in the other bay.

So, a little strange, I suppose I might take away from that is there's an issue with how it's handling SSDs particularly, as the HDD is consistent.

Regardin TRIM, I must admit it's the first I've heard of it so did a quick google to get more info. At present it's not enabled - seems it's recommended to have it enabled for longevity, does it have a huge impact on peformance? Could this be causing some oddities in these results?

 

[r6mile]

Hey guys, thanks for your replies. I tried out your suggeston @r6mile of swapping out the drives. Also checked the negotiated speed and it's 3Gbs

With SSD 1 and 2 in bays 1 and 2 (previously 3 and 4) and HDD in 3 (previously 2), read speed is now a more expected 250Mb/s in both (edit) but the write speed has lessed from 75 to 40ish in 1 and increased 40is to 60ish in 2. HDD is similar as it was in the other bay.

So, a little strange, I suppose I might take away from that is there's an issue with how it's handling SSDs particularly, as the HDD is consistent.

Regardin TRIM, I must admit it's the first I've heard of it so did a quick google to get more info. At present it's not enabled - seems it's recommended to have it enabled for longevity, does it have a huge impact on peformance? Could this be causing some oddities in these results?

It never hurts to have it enabled. Just type in the Terminal
sudo trimforce enable
And see if it makes a difference to your SSD speeds.

 

[KeesMacPro]

Could it be that there's no free space left on them?
Is TRIM enabled?

 

[Rv5]

There's space, one is completely empty, the other has about 25gb free. Moved the drives around again, similar results; HDD is the same, SSDs are both showing 250ish read but still not getting above 70s for the write.

Will enable trim and see if that makes a difference!

 

[KeesMacPro]

the other has about 25gb free

You may know this but it's recommended to keep at least 25% of space free..

 

[Rv5]

You may know this but it's recommended to keep at least 25% of space free..

Thanks for the tip! I had 10% in my head but will free up some space accordingly!

And, thanks for all the input - enabling TRIM has resolved the issue!! Now seeing consistent read and write speeds of 240/250 on both SSDs. Super glad it was something so easy to sort out, thanks for pointing that out guys and thanks the terminal command r6mile.

 

[MarkC426]

the samsung 840 evo should have a read/write speed in the SATA II bay's of around ~250-280 mb/s .
Could it be that there's no free space left on them?
Is TRIM enabled?

I second this reply, I have 3 ssd’s in sata bays, all run at ~250mb/s.

 

[h9826790]

There's space, one is completely empty, the other has about 25gb free. Moved the drives around again, similar results; HDD is the same, SSDs are both showing 250ish read but still not getting above 70s for the write.

Will enable trim and see if that makes a difference!

Without TRIM, those empty space isn't really "empty" (zeroed out for next fast write) unless that's a completely new SSD or secure erased.

Most poor sequential write speed of SSD discussed in this forum is due to lack of TRIM. And you solved this already.

The recommendation is about 20% empty space to allow TRIM + GC to work effectively. The 840 itself should have 7% over provision anyway. Therefore, if the drive still have another 10% free space. That should be good enough for most normal usage.

Of course, free up some more space still good practice (for future use, especially there is only 10% free space) if those data aren't really needed. But don't expect the SSD can perform better by further empty up the SSD.

Anyway, a little bit side topic here. I did some tests to see how different file system affect storage performance and here is the result.

APFS

HFS+

ExFAT