cachefilesd - minor documentation errors

This document (7011892) is provided subject to the disclaimer at the end of this document.

Environment


SUSE Linux Enterprise Server 11 Service Pack 2

Situation

The cachefilesd daemon manages persistent disk-based caching of files that are used by network filesystems such as NFS to cache data locally on disk.  It uses a directory as cache on an already mounted filesystem.

The cachefilesd has been included with a SLE 11 SP2 maintenance update and the kernel 3.0.51-0.7.9.1 includes the patch to support the cachefiles framework.

The README and howto.txt in the /usr/share/doc/packages/cachefilesd/ directory provide useful information how to enable it and use it.

Enabling the cache on NFS  is done by attaching an extra option to an NFS mount ("-o fsc")
NFS will use the cache when the mount option 'fsc' is attached to the mount.

The nfs.man page does not mention the 'fsc'/'nofsc' mount option yet. With "mount -o fsc server:/path /mountpoint" fscache will be enabled for NFS and the cache will be in the directory specified in /etc/cachefilesd.conf. Further details will be in the howto.txt

The howto.txt also documents that sysctl files in /proc/sys/fs/nfs/ can be used for monitoring:
(nfs_fscache_to_pages,nfs_fscache_from_pages,nfs_fscache_uncache_page, nfs_fscache_from_error and nfs_fscache_to_error). There's also a note that they are temporary and will be integrated into the NFS per-mount statistics sometime in the future.

This has happened and the sysctl parameters were replaced with fscache stats in "/proc/self/mountstats".
If fscache is enabled on a filesystem, NFS per mount statistics will be displayed on a line in  "/proc/self/mountstats"beginning with "fsc:" followed by 5 numbers.

These number correspond to:
NFSIOS_FSCACHE_PAGES_READ_OK - number of pages read from the cache
NFSIOS_FSCACHE_PAGES_READ_FAIL - number of pages read but not from cache

NFSIOS_FSCACHE_PAGES_WRITTEN_OK
NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL
These two columns are currently not used

NFSIOS_FSCACHE_PAGES_UNCACHED - number of pages removed from cache

The howto will be corrected and a future update will include the information.

Resolution


Cause


Additional Information


Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7011892
  • Creation Date: 06-Mar-2013
  • Modified Date:03-Mar-2020
    • SUSE Linux Enterprise Server

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