# WD My Book Studio 2 failed to recognise both drives after dismounting and erasing on mac **URL:** \ **Category:** External SSD for macOS\ **Created:** [November 17, 2018, 9:50am UTC](https://forums.sandisk.com/t/wd-my-book-studio-2-failed-to-recognise-both-drives-after-dismounting-and-erasing-on-mac/360151 "2018-11-17T09:50:16Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Petri\_de\_Pita](https://sea2.discourse-cdn.com/sandisk/user_avatar/forums.sandisk.com/petri_de_pita/32/44821_2.png) [@Petri\_de\_Pita](https://forums.sandisk.com/u/Petri_de_Pita)\ **Post date:** [November 17, 2018, 9:50am UTC](https://forums.sandisk.com/t/wd-my-book-studio-2-failed-to-recognise-both-drives-after-dismounting-and-erasing-on-mac/360151/1 "2018-11-17T09:50:16Z")
Hello My 4TB WD Studio 2 broke down, and after checking with Disk Utility on mac it told me to backup if possible and change drive. I decided to dismantle both drive and test them on an external HDD docking system. both were unreadable with Disk Utility but I could erase them. That is what I did for both disks. Then I put them back into the Studio 2 and put power on, light was not blinking, it was still so I plugged into the mac but mac did not recognise the drive and asked me if I wanted to erase, I did and now I got one drive at 4TB instead of 2… What did I do wrong ? thank you in advance for your answers ---
**Author:** ![asp73](https://avatars.discourse-cdn.com/v4/letter/a/958977/32.png) [@asp73](https://forums.sandisk.com/u/asp73)\ **Post date:** [November 20, 2018, 5:24pm UTC](https://forums.sandisk.com/t/wd-my-book-studio-2-failed-to-recognise-both-drives-after-dismounting-and-erasing-on-mac/360151/2 "2018-11-20T17:24:24Z")
Hi Petri\_de\_Pita, It seems that issue is with the My Book Studio enclosure. You should try to check both drives in another My Book Studio enclosure.