After converting a Synology SHR‑1 (mirrored) volume to SHR‑0 (single-disk), you will likely want to expand your storage pool to use the extra capacity of the new disk you originally mirrored with. Here’s a step-by-step guide using SSH and command-line tools to safely resize your volume.

Note: This guide assumes you have already converted your SHR‑1 to SHR‑0 and are working with a single active disk. Always backup your data before making changes to partitions, RAID, or LVM.

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Step 1 — Verify your disk and partition

First, check the current disk layout:

sudo parted /dev/sdb print

Example output before resizing:

Number  Start   End     Size    File system
1      4MB     8.5GB   8.5GB   ext4
2      8.5GB   10.7GB  2.1GB   swap
5      10.9GB  8TB      8TB

Notice partition 5 (the data partition) is still the size of the old disk.

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Step 2 — Resize the partition to the full disk

Use parted to expand the partition:

sudo parted /dev/sdb
(unit %)
resizepart 5 100%
quit
Information: You may need to update /etc/fstab.

• This resizes partition 5 to occupy all remaining space on the disk.
• The unit % option ensures it goes to the end of the disk.

Note: Parted may display You may need to update /etc/fstab — this can be ignored on Synology.

Then tell the kernel to re-read the partition table:

sudo partprobe /dev/sdb

No output means it was successful.

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Step 3 — Grow the mdadm RAID array

Next, expand the RAID metadata to use the full partition:

sudo mdadm --grow /dev/md2 --size=max

Check progress:

sudo mdadm --detail /dev/md2

Once complete, mdadm now sees the full disk size.

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Step 4 — Resize the LVM physical volume

Synology SHR uses LVM on top of mdadm. Resize the PV:

sudo pvresize /dev/md2

This allows LVM to see all free space in the array.

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Step 5 — Extend the logical volume

Grow your volume to use all free space:

sudo lvextend -l +100%FREE /dev/vg2/volume_1

Example output:

Size of logical volume vg2/volume_1 changed from 7.27 TiB to 10.90 TiB.

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Step 6 — Resize the filesystem

Finally, expand the filesystem so DSM sees the new space.

If Btrfs (most modern Synology volumes):

sudo btrfs filesystem resize max /volume1

If ext4 (older volumes):

sudo resize2fs /dev/vg2/volume_1

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Step 7 — Verify

Check the volume size:

df -h

You should now see the full capacity of your new disk.

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Summary

With these steps, you have:

1. Resized the data partition to fill the new disk.
2. Expanded the mdadm RAID array.
3. Updated LVM to use all free space.
4. Extended the logical volume.
5. Resized the filesystem so DSM recognizes the full size.

Your SHR‑0 volume is now healthy and fully expanded, ready for use — all without losing any data.

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This method is safe for single-disk SHR volumes and works after converting from SHR‑1 to SHR‑0, allowing you to upgrade to larger disks seamlessly.

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