What does btrfs scrub do?

What does btrfs scrub do?

btrfs scrub is used to scrub a btrfs filesystem, which will read all data and metadata blocks from all devices and verify checksums. Automatically repair corrupted blocks if there’s a correct copy available.

Is btrfs cluster aware?

Btrfs is SSD-aware and exploits TRIM/Discard to allow the file system to report unused blocks to the storage device for reuse. On SSDs, Btrfs avoids unnecessary seek optimization and aggressively sends writes in clusters, even if they are from unrelated files.

What is a btrfs subvolume?

A subvolume is a part of filesystem with its own independent file/directory hierarchy. Note: A subvolume in btrfs is not like an LVM logical volume, which is block-level snapshot while btrfs subvolumes are file extent-based. A subvolume looks like a normal directory, with some additional operations described below.

How do you mount a btrfs subvolume?

You can actually mount a subvolume in basically the same way that you have always mounted entire fillesystems, all you have to do is add “-o subvol=name” or “-o subvolid=ID” to the mount command or /etc/fstab. When you do this, the directory associated with the subvolume will be the top level of the mounted filesystem.

How often should I scrub btrfs?

1 Answer. btrfs-scrub manpage recommends to run it monthly: The user is supposed to run it manually or via a periodic system service. The recommended period is a month but could be less.

How do you use btrfs scrub?

Use the btrfs scrub start command to start a scrub on all the devices of a file system or on a single device. The syntax is as follows: # btrfs scrub start [-BdqrR] [-c ioprio_class Do not run in the background and print statistics when finished.

How do you btrfs?

Step 1: Installing and Creating Btrfs Filesystem

1. Press ‘n’ for creating new partition.
2. Then choose ‘P’ for Primary partition.
3. Next choose the partition number as 1.
4. Define the default value by just pressing two times Enter key.
5. Next press ‘P’ to print the defined partition.
6. Press ‘L’ to list all available types.

What do you need to know about Btrfs scrub?

DESCRIPTION btrfs scrub is used to scrub a btrfs filesystem, which will read all data and metadata blocks from all devices and verify checksums. Automatically repair corrupted blocks if there’s a correct copy available. Note: Scrub is not a filesystem checker (fsck) and does not verify nor repair structural damage in the filesystem.

Where do I find the subvolume ID in Btrfs?

If –subvolid is used, must point to a btrfs filesystem. See btrfs subvolume list or btrfs inspect-internal rootid how to get the subvolume id. The corresponding directory is removed instantly but the data blocks are removed later in the background. The command returns immediately.

What’s the difference between snapshot and subvolume in Btrfs?

A snapshot is also subvolume, but with a given initial content of the original subvolume. A subvolume in btrfs is not like an LVM logical volume, which is block-level snapshot while btrfs subvolumes are file extent-based.

Why is scrub not a filesystem checker?

Note: Scrub is not a filesystem checker (fsck) and does not verify nor repair structural damage in the filesystem. It really only checks checksums of data and tree blocks, it doesn’t ensure the content of tree blocks is valid and consistent.

https://www.youtube.com/watch?v=8yDkE7l_Usc