Change to RAID 0

[Kraveylicious]

I've got an HP 8300 running bare metal DSM 6.2.3-25426 Update 3 using Jun's 1.03b loader with three disks in RAID 5. Constant uptime is less important than total storage space, which is why I'd like to change to RAID 0.

 

I've decided that I don't need the redundancy since I have a weekly backup I make to a single USB drive using Hyperbackup and keep in a separate building. In the Hyperbackup task, I have selected every shared folder, application and service I can for backup. I've also backed up the configuration file via the Control Panel.

 

Is the best way to do this to Erase and Restore in the Control Panel, then I would assume the discovery wizard would prompt me to go through the Synology setup wizard, choose RAID 0, import my .dss config file and import my backup via Hyperbackup? Before I obliterate the existing server, I want to have a solid plan in place. Thanks!

Edited January 25, 2021 by Kraveylicious
added config backup info

[flyride]

mdadm should allow you to reshape without unmounting, and it is easier if you don't have to.  I would stop Docker from Package Manager before trying a mounted reshape however.

The only command I believe you should have to do is the reshape (decreasing the array size in the article would not apply to you). I expect that DSM will automatically increase your Storage Pool and volumes when more space is available, but if it does not, it's easy to do.

 

i.e:

# mdadm --grow /dev/md2 --level=0

 

Obviously, have a backup before doing anything like this.  The reshape is dependent upon kernel support, and Synology modifies mdadm for their own purposes, so no guarantee it will work.  If it does work, you save time.  If it doesn't, you are back to the manual process.

Edited January 26, 2021 by flyride

[flyride]

Well, you can just remove one of the disks and what is left will technically be RAID0 (a critical RAID5 is a RAID0), with space lost for parity.

 

Manual reshape of the array with mdadm ought to permanently convert it to RAID0.  You might have to unmount your volume and stop the array first.

 

See this: https://wysotsky.info/mdadm-convert-raid5-raid10/

Edited January 25, 2021 by flyride

[Kraveylicious]

21 hours ago, flyride said:

Well, you can just remove one of the disks and what is left will technically be RAID0 (a critical RAID5 is a RAID0), with space lost for parity.

 

Manual reshape of the array with mdadm ought to permanently convert it to RAID0.  You might have to unmount your volume and stop the array first.

 

See this: https://wysotsky.info/mdadm-convert-raid5-raid10/

Thanks for the suggestion. I may give this a shot. I assume first step is to SSH in as an administrator. In the first unmount step, I think I'd just make sure that no computers have any of the shared folders mounted?

 

From what I can tell, the volumes are as follows:

• /dev/md0 is the bootloader USB
• /dev/md2 is one and only volume on the Xpenology (volume1)
• /dev/sdu1 is the backup external hard drive that I'm using with Hyper Backup

Based on my usage, I would change the size of the filesystem and array to "5T" and just copy paste all the commands on the page while modifying their volume as /dev/md2, skipping the unmount command and stopping right before the RAID 10 conversion, correct?

 

Any disadvantages to doing it this way as opposed to deleting and recreating the storage pool?

 

Edited January 26, 2021 by Kraveylicious
edit screenshot

[Kraveylicious]

On 1/25/2021 at 10:25 PM, flyride said:

mdadm should allow you to reshape without unmounting, and it is easier if you don't have to.  I would stop Docker from Package Manager before trying a mounted reshape however.

The only command I believe you should have to do is the reshape (decreasing the array size in the article would not apply to you). I expect that DSM will automatically increase your Storage Pool and volumes when more space is available, but if it does not, it's easy to do.

 

i.e:

# mdadm --grow /dev/md2 --level=0

 

Obviously, have a backup before doing anything like this.  The reshape is dependent upon kernel support, and Synology modifies mdadm for their own purposes, so no guarantee it will work.  If it does work, you save time.  If it doesn't, you are back to the manual process.

After logging in as root, I ran the above command and 20 hours later my RAID 5 storage pool was converted to RAID 0. Unfortunately, it only converted two disks and left the third Initialized but not part of the pool. I was unable to add it (maybe there's a way with mdadm) so in the end I ended up deleting the storage pool and restoring from a backup.

 

Thanks for the help!

[jensmander]

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