I want to replace my Toshiba HDD (Model: MQ01ABD100) with a faster one. I found Western Digital SSD (Model: WD Blue 3D NAND SATA SSD) for a good price however I'm concerned about a form factor: Toshiba - 2.5-inch, 9.5mmH and WD - 2.5-inch/7mm cased, M.2 2280. Whoever knows, please, advise if WD will fit the slot. Thank you in advance.
You don't specify the exact model for the Western Digital, which is problematic in this case.
You do mention it is an "M2 2280" model, while at the same time mentioning it is a 2.5"/7 mm drive.
The Western Digital Blue drives can come in BOTH versions, but they are mutually exclusive.
It is either a M2 (which won't fit as it is a totally different connector and formfactor) or it is a 2.5" drive which will fit. (The 7mm is Ok. Less height than the old drive always fits, because the mounting holes will be the same place).
To be abolutely clear: Your Toshiba is a regular SATA 2,5" inch drive. Any replacement has to be also a 2.5" SATA drive, not a M2. As for height: As the old drive is 9.5mm, both 7 and 9.5mm models will fit. 12mm might also fit, but that depends on the mounting frame/space inside the laptop.