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.
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
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- SUSE Linux Enterprise Server
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