Peter Gamble

I want to put in two SSD's in a 27" iMac Retina 5K (mid 2017)? I understand that such iMac has two different ports for two...

There is a lot of misinformation and confusion on this topic. Currently, no utility can rebuild the directory of APFS disks on Mac. That includes DiskWarrior (the best in the repair arsenal), TechTool Pro (second choice) and Drive Genius (third choice). Worst of all, macOS versions above 10.12 Sierra re-format disks as APFS, so users are left in the cold. Apple should not do that!!! The reason is that Apple has not yet released documentation about how to write to such APFS disks, as they did about how to read them by September 2018 (after releasing macOS 10.14 Mojave; a year after releasing APFS for Mac and even before for iOS by March 2017!!!). • Some developers are clear about it in their web pages, like Prosoft Engineering: Drive Genius 5. Rebuild utilities are not supported on APFS. https://www.prosofteng.com/drive-genius-mac-protection-software++ • Micromat is misleading: TechTool Pro. In addition to native Mac drive formats, Mac OS Extended and APFS, Techtool Pro supports testing and repair of MS-DOS...

Great. What SSD model inside iMac Pro (4 TB) shows at "Apple - About This Mac - System Report - Hardware - Storage - Physical Drive - Device Name"? For instance, iMac 5K 27-inch shows "APPLE SSD SM2048L", which stands for SaMsung SSD 2,048 GB (2 TB). Thanks and Happy Christmas!

Surprising results for 27" iMac Retina 5K (mid 2017): TESTED: 2017 iMac 5K SSD Speed vs 2015 iMac 5K (Surprising Finding) Thus the 2017 iMac 5K is substantially slower for everyday tasks that involve intensive I/O with smaller reads, in spite of the 40% greater speed for large reads. <https://macperformanceguide.com/blog/201...-2017iMac5K-SSD.html> 2017 iMac 5K: Flash Drive (SSD) 2015 iMac 5K: writes at 1520 MiB/sec and reads at 2075 MiB/sec 2017 iMac 5K: writes at 2102 MiB/sec and reads at 2915 MiB/sec. <https://macperformanceguide.com/iMac5K_2...-flashDriveSSD.html> — That is less read speed than Samsung 960 PRO with sequential R/W (read/write) speeds up to 3,500/2,100 MB/s and random R/W speeds up to 440/360K IOPS, respectively.

Two SSD modules in RAID?

Step 8. It says “Toshiba TSB4227VE8434CHNA11926 and TSB4227VE8437CHNA11926 flash storage (512 GB total)”.

Does it mean that it has two SSD sticks? RAID? Thanks!

RAID 0 SSD? From Samsung?

@mark

You said: "The data isn’t striped. As already alluded to, that implies to separate controllers on two separate drives. This is one controller accessing chips on two separate boards. As the previous poster pointed out, this would be no different that putting all the chips on a single board, just less flexible in terms of space. which is at a premium inside this enclosure”.

Data not stripped on SSD? Do you have a proof of that? How can it achieve 3.3GB/s write and 2.8GB/s read without RAID 0 ?

Anyway, even if data is not striped, do you mean that if one SSD fails, data can be recovered on the other? If not, it is like RAID 0 in relation to data protection.

@dgramatzki

I see a big difference. If data is stripped between two SSD, it is like RAID 0 for data protection by definition.

“Think of it more like a bank of RAM. Each operation is bounced between the two modules (inter-leaved)”.

Then it is equivalent to RAID 0 in relation to data protection: if one SSD fails, all is lost. Or if the controller chip fails. Or if the main board fails in this case, since the SSD is paired with it. You cannot take the SSD out for troubleshooting or data recovery or booting in other Mac.

Please, let is know if you can configure it as two separate SSD.

Is the SSD paired to logic board? If the logic board fails, can the data in SSD be recovered? Thanks.

Is the SSD encryption mandatory? Can it be turned off or disabled? Thanks.

“It’s one SSD controller on two sticks of dumb NAND, no need for a RAID”.

Really? Do you mean that the iMac Pro has 2.8 GB/s read & 3.3 GB/s write without RAID 0? Why not use then a single SSD blade-stick instead if two?