This session discusses how self-heal daemon in replicate translator performs data, metadata, entry heals

1. Glusterfs Session #17
Self-heal daemon (Part 2)
Data, metadata and entry healing
ravishankar.n@pavilion.io

2. Agenda
In the previous session:
- Intro to self-heal daemon (shd)
- Types of crawl in shd
- Code walkthrough
In this session:
- Types of heal needed for a given file/directory
- Code walkthrough

3. Types of heal: Metadata heal, data heal and entry-heal
Files: metadata heal (and/or) data heal
Example: # getfattr -d -m . -e hex /data/bricks/brick1/FILE
getfattr: Removing leading '/' from absolute path names
# file: data/bricks/brick1/FILE
security.selinux=0x73797374656d5f753a6f626a6563745f723a6574635f72756e74696d655f743a733000
trusted.afr.dirty=0x000000000000000000000000
trusted.afr.testvol-client-2 =0x000000010000000000000000 ===> Data=yes, metadata=no, entry=yes
trusted.gfid=0xffd76721fe014ac9a0c6f1314a6f48b0
trusted.gfid2path.496139f0a2596ca2=0x30303030303030302d303030302d303030302d303030302d3030303030303030303030312f46494c45
trusted.glusterfs.mdata=0x0100000000000000000000000061801023000000001a0a3d6b0000000061801023000000001a0a3d6b0000000061800fff00000000
2c429d3a
Directories: metadata heal (and/or) entry heal
Example: # getfattr -d -m . -e hex /data/bricks/brick1/DIR/
getfattr: Removing leading '/' from absolute path names
# file: data/bricks/brick1/DIR/
security.selinux=0x73797374656d5f753a6f626a6563745f723a6574635f72756e74696d655f743a733000
trusted.afr.dirty=0x000000000000000000000000
trusted.afr.testvol-client-2 =0x000000000000000000000001 ===> Data=no, metadata=no, entry=yes
trusted.gfid=0xca3d6f325e7943e0a696fb05526c4803
trusted.glusterfs.dht=0x000000000000000000000000ffffffff

4. Code walkthrough
~/workspace/glusterfs$ ls xlators/cluster/afr/src/afr-self-heal*
xlators/cluster/afr/src/afr-self-heald.c
xlators/cluster/afr/src/afr-self-heald.h
xlators/cluster/afr/src/afr-self-heal.h
xlators/cluster/afr/src/afr-self-heal-common.c
xlators/cluster/afr/src/afr-self-heal-metadata.c
xlators/cluster/afr/src/afr-self-heal-name.c
xlators/cluster/afr/src/afr-self-heal-data.c
xlators/cluster/afr/src/afr-self-heal-entry.c

5. Functions/ variables
Entry point:
afr_selfheal() <---- called either by shd or client side heal
afr_selfheal_data()
afr_selfheal_metadata()
afr_selfheal_entry()