Compression and Encryption

A volume’s compression algorithm and, on S3, its server-side encryption are recorded on the volume. You choose them at init and can change them later with flexblock update. A change applies to later writes only.

Procedure

Caution

The daemon must be stopped. Only --device-size can be changed while the daemon is serving.

1. Stop cleanly: unmount, then stop the daemon. See Stopping Cleanly.

2. Make the change.

   sudo flexblock update /dev/nvme1n1p1 --compression lz4
   sudo flexblock update /dev/nvme1n1p1 --s3-no-sse

3. Start the daemon again and mount.

Add --dry-run to print the old and new values without changing anything.

Flag	Meaning
--compression <none|lz4|zstd|snappy>	New algorithm for later writes. The default at init is zstd.
--s3-sse	S3 only: request server-side encryption (SSE-S3) for later writes.
--s3-no-sse	S3 only: stop requesting server-side encryption, for stores that reject the header.

On the other providers, server-side encryption is managed by the provider and there is nothing to change.

Existing objects stay readable

You do not need to rewrite anything. Each object in the bucket records its own compression, so objects written under the old setting stay readable after the change.

Repairing the volume superblock

Run with no change at all, update repairs a volume superblock that object storage reports missing or stale. One that records a larger size than the device needs --device-size at that size.

sudo flexblock update /dev/nvme1n1p1

Related

• Amazon S3
• flexblock update reference
• flexblock init reference