If you haven’t done so already, use the forum search feature (magnifying glass icon top right). There are a number of past discussions about restsdk-server and other services that run on the single bay/single drive My Cloud that some have ended up disabling using SSH.
https://community.wd.com/search?q=restsdk-server%20%23personal-cloud-storage%3Awd-my-cloud
For example this post:
Many of us first gen users have disabled Restsdk and several other services in an attempt to deal with various My Cloud issues, in particular the “sleep” issue that is well discussed in many other posts in this OS3 subforum. Generally for OS3 v4.x firmware users they can use the /etc/rc2.d/S98user-start file to stop certain services when the My Cloud boots up.
A basic example of the S98user-start file I’ve run on a single bay OS3 v4.x firmware My Cloud. Unknown if the 2nd gen single bay v2.x firmware uses the same commands or user-start file.
# Attempts to fix sleep issue with Samba
/etc/init.d/samba stop
mount -t tmpfs -o mode=0700,noatime,size=2m tmpfs /etc/samba/msg.sock/
/etc/init.d/samba start
# Stop certain unwanted wakeups
mount -o remount,noatime,nodiratime /dev/root /
# Stopped My Cloud services
/etc/rc2.d/S20restsdk-serverd stop
/etc/rc2.d/S85wdmcserverd stop
/etc/rc2.d/S86wdphotodbmergerd stop
/etc/rc2.d/S92wdnotifierd stop
