How to check the fragmentation and do defragmentation on ext4? Helpful check for home directory

[#1]

Today, I got a question about how to check the fragmentation of ext4 filesystems, as most common for the Data Center edition or Server edition setups. 

That article is the next step of a previous story about the  improvement of latency for volumes.

Of course, some users can ask why we need to do defragmentation on ext4 as it’s not fragmented. As an answer, I would recommend checking out the presentation from LinuxCon 2010  with the name Outline of Ext4 File System & Ext4 Online Defragmentation Foresight  and watch the small video with fragmentation (https://www.youtube.com/watch?v=w0TzYtuh8D0)

So let’s start to use one small command line utility e4defrag. 

Online man page you can find here: http://manpages.ubuntu.com/manpages/focal/man8/e4defrag.8.html

1. Get report of fragmentation:

$ sudo e4defrag -c /location

1. After checking the results you can run the defragmentation:

$ sudo e4defrag /location

1. If you want extra info:

$ man e4defrag

This is result on out test env:

Reference:

• Akira Fujita - Outline of Ext4 File System & Ext4 Online Defragmentation Foresight - https://events.static.linuxfound.org/slides/2010/linuxcon_japan/linuxcon_jp2010_fujita.pdf
• Takashi Sato - ext4 online defragmentation -  https://www.kernel.org/doc/ols/2007/ols2007v2-pages-179-186.pdf
• Source code of utility - https://github.com/tytso/e2fsprogs/blob/master/misc/e4defrag.c
• Previous article: The story about how to improve the background indexing Lucene job for Jira in one shot (just non-standard way)?  

Hope it helps for your DC installations on ext4.

Cheers,

Gonchik Tsymzhitov

[DPKJ]

Will this help if instances are hosted on AWS, using Atlassian provided templates?

[Gonchik Tsymzhitov]

Good question, let me investigate that possibility. 

@DPKJ Could you share some information about your AWS installation, please?

[DPKJ]

Here it is - https://aws.amazon.com/quickstart/architecture/jira/

[Sergey Papurin]

@DPKJ 

On AWS default is XFS not EXT4
It can be checked and defragged with xfs_db and xfs_fsr