Drive letter Z always disappears

[RogerHeirbaut]

Drive letter Z keeps disappearing. I have 3 disk partitions (C, P and Z). The drive letter Z disappears from time to time, but the partition is still availble as are the data in it.  I can easily add the letter again in Windows Disk Management, but a few days later it is gone again. When I run an HP diagnostic test immediately after resetting the letter to Z, it then immediately disappears during the diagnostic test itself. I tried assigning a different  letter (Y) instead, and then the problem does not occur. But for me it is not possible to exchange Z with Y permanently because in that case all my file references would fail.

[BeemerBiker]

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@RogerHeirbaut wrote:

Drive letter Z keeps disappearing. I have 3 disk partitions (C, P and Z). The drive letter Z disappears from time to time, 

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There are two possibilities that I can think of.  One is to bring up the event viewer and look for disk drive or controller errors.

The other is the possibility that you are using a reserved partition that is normally  hidden or system.  Assigning a letter to it will temporarily unhide it.

Please run the diskpart app from the administrator command prompt and post the image back here.  It should look somewhat like the following:

See if you can get an image both  with the letter and with no letter.

A quick fix is to add an additional drive using USB adapter, copy your files to it, then remove adapter and attached drive as "Z" on the SATA cable and let that old partition remain hidden.

[RogerHeirbaut]

Hello!  Thanks for your answer.  I cannot find any related errors in the event viewer.  Hereafter you see the result of the diskpart command, with and without drive letter 'Z'.  

[BeemerBiker]

I just realized you have 7 partitions and, i am guessing, only one drive.  Possibly that is the problem but it is suspicious that "Y" works and not "Z".

There is a limit of 4 partition in windows (also Ubuntu)  but it can be gotten around by specifying simple partitions.

Please describe your problem and  ask over at https://answers.microsoft.com/en-us

You might try the following but I suspect the problem will remain.1

https://www.diskpart.com/diskpart/assign-drive-letter-4125.html

[RogerHeirbaut]

Well, in fact I have 2 SSD drives, each 1 TB.    Because the internal drive dit not have enough capactity for me I added another one on which partitions M and S are defined.  The problematic 'Z' partition is on my internal drive, and also the C and the P.  So I have 3 partitions one my internal drive and 2 on my external drive.