You may be able to reconfigure the RAID 6 to RAID 5. It is not, by design, data-destructive, so you should be able to reconfigure on the fly without data loss. However, you have no business doing this if you don't have a backup of the data. If you don't have a backup, then you should put ALL your plans on hold and focus on a backup strategy first. You can find the Reconfigure option in the drop-down menu of Available Tasks for your RAID 6 on the OMSA > Storage > PERC > Virtual Disk page.
Our PE r740xd has a RAID-6 disk group setup. We would like to convert it into a RAID-5 because we are running out of space, and we thought that using a spare disk from the RAID-6 could help us by converting the said RAID type. We always see OMSA (thru this forum and internal suggestions within our group) as a tool to help resolve our concern. But of course, we are fearing of losing a lot of data if we convert RAID-6 to RAID-5. Also, we are not considering any plan converting the RAID type by erasing RAID-6 and creating RAID-5 from the same disk group. Can you please help confirm if that is the case or otherwise? Thank you.
From RAID-6 to RAID-5