System information

Chapter 10. FS-Cache
FS-Cache is a persistent local cache that can be used by file systems to take data retrieved from over
the network and cache it on local disk. This helps minimize network traffic for users accessing data
from a file system mounted over the network (for example, NFS).
The following diagram is a high-level illustration of how FS-Cache works:
Fig ure 10.1. FS- Cach e O verview
FS-Cache is designed to be as transparent as possible to the users and administrators of a system.
Unlike cachefs on Solaris, FS-Cache allows a file system on a server to interact directly with a
client's local cache without creating an overmounted file system. With NFS, a mount option instructs
the client to mount the NFS share with FS-cache enabled.
FS-Cache does not alter the basic operation of a file system that works over the network - it merely
provides that file system with a persistent place in which it can cache data. For instance, a client can
still mount an NFS share whether or not FS-Cache is enabled. In addition, cached NFS can handle
files that won't fit into the cache (whether individually or collectively) as files can be partially cached
and do not have to be read completely up front. FS-Cache also hides all I/O errors that occur in the
cache from the client file system driver.
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