iMac 27" late-2015 1TB SSD and 3TB Fusion Drive models

[j1104638]

Hi all,

If you have iMac 27" late-2015 with original Apple 1TB SSD or 3TB Fusion Drive or you know the following info, please share:

1. is 1TB SSD NVMe? I think you could check it by going to  -> About this Mac -> System Info and looking if the SSD is under NVMExpress or SATA/SATA Express tab; please post a screenshot if you can;

2. what model is 3TB HDD within 3TB Fusion Drive? I think you could check it by going to  -> About this Mac -> System Info and looking up the model number and/or revision of it; please post a screenshot if you can.

Thank you for the help!

 

[tubeexperience]

The SSD is AHCI only.

 

[mpe]

Fusion drive (both 2TB and 3TB) contain SM0128G, which is x4 (8.0 GT/s) PCIe drive. I don't think it is using NVMExpress.

As far as I know HDDs are Seagate ST2000DM001 (2TB Fusion) or ST3000DM001 (3TB Fusion)

 

[j1104638]

The SSD is AHCI only.

Sad news. Thank you.
[doublepost=1470172788][/doublepost]

Fusion drive (both 2TB and 3TB) contain SM0128G, which is x4 (8.0 GT/s) PCIe drive. I don't think it is using NVMExpress.

As far as I know HDDs are Seagate ST2000DM001 (2TB Fusion) or ST3000DM001 (3TB Fusion)

Sad as well.

Using photo from MacSales tear down I hoped both 1TB SSD and SSD of 3TB Fusion Drive are NVMe.

Thank you.

 

[mpe]

I think only the small Fusion (the crippled 24GB in 2015 1TB Fusion drive) is NVMe.

However, I don't think it makes any real difference except in benchmarks (when the Fusion is empty). The 8GT/s part in 2TB/3TB is really, really fast.

 

[CWallace]

The new MacBook Retina uses NVMe so Apple may add it to the next refresh, but even with AHCI my 1TB SSD is ridiculously good.

 

[vmflapem]

Could someone please explain the difference between the NVMe and AHCI? I tried to do some research but I could not understand. I'm thinking of buying a 1TB SSD 5K imac but is this a deal breaker for the current imac 5K?

 

[mpe]

NVMe is a more modern protocol set optimised for interacting with SSD storage over PCIe. Older standards such as AHCI over SATA/PCIe contains some idiosyncrasies related to dealing with rotational nature of storage devices. Interfaces needs do necessary translations, queuing, etc.

NVMe is designed from ground up to interact with RAM-like media more efficiently. In theory that allows for faster access, lower latencies, more efficient parallel access, lower overhead, etc.

Practical difference for consumer hardware is not that significant. Current generation of SSDs, especially those connected via PCIe bus in Macs are crazy fast.

 

[vmflapem]

NVMe is a more modern protocol set optimised for interacting with SSD storage over PCIe. Older standards such as AHCI over SATA/PCIe contains some idiosyncrasies related to dealing with rotational nature of storage devices. Interfaces needs do necessary translations, queuing, etc.

NVMe is designed from ground up to interact with RAM-like media more efficiently. In theory that allows for faster access, lower latencies, more efficient parallel access, lower overhead, etc.

Practical difference for consumer hardware is not that significant. Current generation of SSDs, especially those connected via PCIe bus in Macs are crazy fast.

Awesome, Thanks! Just one more question - is it true that a 1TB SSD is faster than a 512GB SSD assuming that I only use 200GB of storage?

 

[mpe]

Awesome, Thanks! Just one more question - is it true that a 1TB SSD is faster than a 512GB SSD assuming that I only use 200GB of storage?

It is complicated.

It shouldn't be slower (supposing everything else is equal - such as link speed, organisation of chips, firmware, controller). Most SSD's are slower at writes when being close to full though. So if you were used close to 500GB of capacity, the 1TB could be faster as the firmware could struggle to find "recycled" cells when writing.

However, some low-end SSD's (64GB/128GB) scale down by using fewer memory chips than their 256GB/512GB/1TB+ counterparts from the same series. These could be slower.

 

[vapourtrails]

What speed is the HD portion of the fusion drive? Is it 7200 or 5400? Also, is it a full size drive or a laptop drive?

 

[CWallace]

I believe the 2TB and 3TB are both 7200RPM and the 1TB is 5400RPM.