LFS-CHANGELOG(1) Lustre User Utilities LFS-CHANGELOG(1)

# [NAME](#NAME)

lfs-changelog, lfs-changelog\_clear - client utility to read and clear Lustre changelogs

# [SYNOPSIS](#SYNOPSIS)

`lfs changelog` \[**--follow**] \[**--user** *USERNAME*] \[**--mask** *MASK*] *MDTNAME* \[*STARTREC* \[*ENDREC*]]

`lfs changelog_clear` *MDTNAME* *ID* *ENDREC*

# [DESCRIPTION](#DESCRIPTION)

**lfs changelog** displays the metadata changes on an MDT. Start point *STARTREC* and end point *ENDREC* are optional.

**lfs changelog\_clear** indicates that changelog records previous to *ENDREC* are no longer of interest to a particular consumer *ID*, potentially allowing the MDT to free up disk space. An *ENDREC* of 0 indicates the current last record.

Changelog consumers must be registered on the MDT node using [**lctl-changelog\_register**(8)](/man/enterprise-packages/lustre/lctl-changelog_register.8).

# [OPTIONS](#OPTIONS)

[**--follow**](#follow)

Block and wait for new changelog records to arrive.

[**--user USERNAME**](#user)

Specify a registered changelog username for filtering. The format of *USERNAME* can be a username or numeric ID, e.g., "cl1", "cl1-user", "1", or "user".

[**--mask MASK**](#mask)

Specify a changelog event filtering mask in the same format as [**lctl-changelog\_register**(8)](/man/enterprise-packages/lustre/lctl-changelog_register.8), e.g., "creat,unlnk,+open,-hsm". If *MASK* is not specified, the user's *MASK* specified to [**lctl-changelog\_register**(8)](/man/enterprise-packages/lustre/lctl-changelog_register.8) will be used.

# [RETURN VALUES](#RETURN_VALUES)

Return 0 on success or a errno value on failure.

# [ERRORS](#ERRORS)

[**EINVAL**](#EINVAL)

One or more invalid arguments are given.

[**ENOENT**](#ENOENT)

MDT's changelog char device or changelog user not found.

[**EACCES**](#EACCES)

Not enough permissions to open the changelog char device. By default, the device is only accessible to the root user.

[**EIO**](#EIO)

Failed to read the changelog record on the MDT.

# [NOTES](#NOTES)

Certain userspace tools might rely on past Lustre behavior of displaying the shard's parent FID instead of the real parent FID, in changelog records related to striped directories or filesystem objects contained within them; if this behavior is needed for compatibility, please set mdd.\*.enable\_shard\_pfid=1. This tunable might be deprecated in a future Lustre release.

# [EXAMPLES](#EXAMPLES)

Register 2 changelog consumers on MDT0000:

```
mds# lctl --device lfs1-MDT0000 changelog_register
lfs1-MDT0000: Registered changelog userid 'cl1'
mds# lctl --device lfs1-MDT0000 changelog_register -u dirs -m mkdir+rmdir
lfs1-MDT0000: Registered changelog userid 'cl2-dirs'
```

```
Set changelog mask to generate changelogs for file creations:
```

```
mds# lctl set_param mdd.lfs1-MDT0000.changelog_mask=CREAT
mdd.lfs1-MDT0000.changelog_mask=CREAT
```

```
Generate changelogs by creating some files on the fs:
```

```
client# touch /mnt/lfs1/test{1..101}
```

```
Read changelog from number 0 to 99 on MDT0000:
```

```
client# lfs changelog lfs1-MDT0000 0 99
0 01CREAT 11:03:54.129724442 2022.11.22 ... p=[0x200000007:0x1:0x0] test1


 ....
99 01CREAT 11:03:54.129724465 2022.11.22 ... p=[0x200000007:0x1:0x0] test100
```

```
Read changelog records using registered user cl1:
```

```
client# lfs changelog --user cl1 lfs1-MDT0000
100 01CREAT 11:03:54.129724492 2022.11.22 ... p=[0x200000007:0x1:0x0] test101
```

```
Read changelog records for registered user cl2-dirs with an extra filter mask:
```

```
client# lfs changelog --user cl2-dirs --mask unlnk lfs1-MDT0000
No record found.
```

```
Inform MDT0000 that changelogs lower than 100 are not needed for user
cl1:
```

```
client# lfs changelog_clear lfs1-MDT0000 cl1 99
```

```
Inform MDT0000 that changelogs lower than 200 are not needed for user
cl2-dirs:
```

```
client# lfs changelog_clear lfs1-MDT0000 cl2-dirs 199
```

```
The changelogs from 0 to 99 are cleared by the MDT:
```

```
client# lfs changelog lfs1-MDT0000 0
100 01CREAT 11:03:54.129724492 2022.11.22 ... p=[0x200000007:0x1:0x0] test101
```

# [AVAILABILITY](#AVAILABILITY)

**lfs changelog** and **lfs changelog\_clear** are part of the [**lustre**(7)](/man/enterprise-packages/lustre/lustre.7) filesystem package since release 2.0.0.

# [SEE ALSO](#SEE_ALSO)

[**lfs**(1)](/man/enterprise-packages/lustre/lfs.1), [**llapi\_changelog\_clear**(3)](/man/enterprise-packages/lustre/llapi_changelog_clear.3), [**llapi\_changelog\_recv**(3)](/man/enterprise-packages/lustre/llapi_changelog_recv.3), [**llapi\_changelog\_start**(3)](/man/enterprise-packages/lustre/llapi_changelog_start.3), [**llapi\_changelog\_start\_user**(3)](/man/enterprise-packages/lustre/llapi_changelog_start_user.3), [**lctl-changelog\_deregister**(8)](/man/enterprise-packages/lustre/lctl-changelog_deregister.8), [**lctl-changelog\_register**(8)](/man/enterprise-packages/lustre/lctl-changelog_register.8)

2025-11-25 Lustre

---

Document: lfs-changelog_clear(1) from lustre 2.17.59-r2 (Chainguard OS)
Source: https://github.com/lustre/lustre-release