[SOLVED] SSD Usage and Capacity

[grawlix]

Hello all, I have a couple of questions concerning a particular M.2 SSD in a Dell 2-in-1 folding notebook. Here are some links to the relevant bits:

Notebook
https://www.dell.com/support/home/u...t/product/inspiron-17-7786-2-in-1-laptop/docs

SSD
https://ark.intel.com/content/www/u...es-16gb-m-2-80mm-pcie-3-0-20nm-3d-xpoint.html

This is a relatively new computer, but it has been quarrelsome from the start. It had a tendency to trip into the SupportAssist boot diagnostics and hang up on the very end of a hard drive scan. There are two storage devices, the aforementioned solid-state drive, and a 1TB hard disk drive. Cancelling the diagnostic before the kill screen would put you back into Windows 10 Home.

Against my better advice, the user continued with the machine, and continued to avoid all backup strategies. So, the 1TB hard drive is now dead, with all documents lost. A new hard drive is in it with a fresh, activated install of Windows 10 Home 1903, and seems to be running well enough.

Q1) What was the likely use of that 16GB solid-state drive?

Unfortunately, I did not do a proper inspection until after the catastrophe. Presumably the 1TB drive was the boot drive, so no clues to be had there. Was the 16GB a swap drive? I can't find any discussion of it in Dell's literature.

The SSD currently shows as entirely unallocated. Here's the odd bit, it claims a 13735MB capacity. If I begin to create a volume upon it with Windows 10 Disk Management, I'm allowed to make that volume up to 13733MB. I'm fairly certain these to previous MBs are actually referring to MiB (1 MiB = 1024 x 1024 B), so that would make the capacity just a bit over 14,402,000,000 bytes--that's only 90% of 16GB?

Q2) Does this reduced capacity indicate a failure in the SSD?

Maybe there's some sort of super hidden partition that could be used for UEFI or recovery options? It just seems odd. Here's a bonus question:

Q+) Is there any downside to just cramming a beefier M.2 SSD in there and using it as the boot volume?

Samsung 970 EVO
https://www.newegg.com/samsung-970-evo-500gb/p/N82E16820147690

Thanks for any consideration you make.

 

[TJ Hooker]

The SSD is there to act as a cache for the HDD, to improve storage performance.
https://www.dell.com/support/manual...6ceb27-5785-4bc5-a110-7c376e48c907&lang=en-us

Edit: And I believe that, if properly configured, it should be invisible to the user. They'd just see the 1TB drive, and files would be automatically cached on the SSD using Intel's RST algorithms.

 

[grawlix]

Thanks. I should warn you that an answer is likely to generate more questions from me.

If the SSD is properly configured and working, will it appear as 16GB of unallocated space?

 

[TJ Hooker]

See my edit above. As far as I know the drive should not be visible to the user.

 

[grawlix]

Ok, excellent. I've managed to enable Intel Optane Memory with the RST ui from Intel's website, and it looks to be functioning. The SSD disappeared from Disk Management as well. (Edit: There's a marked improvement in the system drive's benchmarks as well.)

Intel RST's "Storage System View" though, shows the SSD's size to be 13,736 MiB. That appears to be wrong to me.

Edit:

Q3) Is there any way to hide part of a physical drive's capacity from Windows Disk Management?

I understand that the entire drive might not be visible, but if it does appear, shouldn't it have the full capacity? ( GPartEd also identified that SSD as having a 14.4GB capacity.)

 

[USAFRet]

"16GB" drive reading at 13.7GB is entirely normal.
The full size should read as 14.4GB (as GPartEd shows), but that extral little bit might be taken with the cache workings.

16 = 14.4 is simply a difference in reporting units.
Base 10 vs Base 2.
1000 vs 1024.
Human vs Computer

Same as a "1TB" drive will show as 931GB.

 

[grawlix]

I tried to be careful in specifying MB vs MiB for those different bases.

Conservatively, let's say the unit's true capacity is 16,000,000,000 bytes. So that would be 16GB and 14.9GiB respectively.

This unit is reporting a 13735 MB capacity, but I think that's actually MiB. Let's do both:

14.4GB if 13735MiB
13.7GB if 13735MB

At a minimum, it's 1.6GB short, isn't it?

 

[USAFRet]

That 1.6 could be consumed with the caching function. I do not know if that is the case, but a possibility.
In any case....that drive is simply just a cache for the HDD. In that usage, the 'missing space' is mostly irrelevant.

 

[popatim]

...Against my better advice, the user continued with the machine, and continued to avoid all backup strategies...

I have a couple users like that too. One in particular keeps bringing up up every year but never actually does anything about it. I'm to the point where I tell him to give me the credit card and I'll take care of it when he mentions it...
They've already had one drive fail on them earlier this year and still no backup system, just more talk. 😠

 

[grawlix]

I'm not particularly concerned about the loss in storage--it's just want to know if part of it has failed. Even Intel RST is reporting a significantly lower capacity than the spec. It seems like it should know.

 

[USAFRet]

I'm not particularly concerned about the loss in storage--it's just want to know if part of it has failed. Even Intel RST is reporting a significantly lower capacity than the spec. It seems like it should know.

It wouldn't fail 'part way'. An SSD is pretty much all or nothing.

 

[popatim]

It's completely normal. A 32Gb shows up as 27.1 ...

[edit] Decided a pic was worth 1000 words and found a 16Gb that shows it. About a 1/3rd of the way down the page.
https://support.cyberpowerpc.com/hc/en-us/articles/360014651473-Re-enabling-Optane

 

[grawlix]

Thanks for that. I guess there must be some portion reserved for internal use.

32 GB = 32 * 1000^3 B = 29.8 * 1024^3 B = 29.8 GiB