How to downgrade a RAID 1 Volume to Non-RAID

From SynologyWiki

Note: this information is for experienced and knowledgeable users only. This procedure is not officially supported by Synology. Please backup all data before executing this procedure, Synology cannot be held liable should any data loss occur. Any and all risk from this procedure will be held at the owner's risk.

This guide assumes that this is being performed on a DS207 series product, with 2 HDDs in RAID 1 (md2) with devices sda3 and sdb3. The objective of this guide is to convert sda3 from RAID 1 into Non-RAID. The alternative method of converting a RAID 1 volume into Non-RAID is to backup all data from the volume, delete the volume, and then recreate the data volumes as two individual Non-RAID Volumes.

Stop all network services on the Synology product (Photo station, web sevices, download service, etc)
Then perform the following commands via the Telnet interface

> /usr/syno/etc/rc.d/S25download.sh stop
> /usr/syno/etc/rc.d/S20pgsql.sh stop
> /usr/syno/etc/rc.d/S80Samba.sh stop
> umount /volume1
> mdadm -S /dev/md2
> mdadm -Cf /dev/md2 -R -n 1 -l 1 /dev/sda3
> mount /dev/md2 /volume1
> reboot