Hp StoreAll Storage User Manual download pdf (Page 11)

1) The segment server initiating the operation can read files directly from the segment

across the SAN; this is called a SAN READ.

2) The segment server initiating the operation routes writes over the IP network to the

segment server owning the segment. That server then writes data to the segment.

c. All reads and writes must be routed over the IP network between the segment servers.

8. Step 7 assumed that the server had to go to a segment to read a file. However, every segment

server that reads a file keeps a copy of it cached in its memory regardless of which segment

it was read from (in the diagram, two servers have cached copies of File 1). The cached

copies are used to service local read requests for the file until the copy is made invalid, for

example, because the original file has been changed. The file system keeps track of which

servers have cached copies of a file and manages cache coherency using delegations, which

are IBRIX file system metadata structures used to track cached copies of data and metadata.

File system building blocks

A file system is created from building blocks. The first block comprises the underlying physical

volumes, which are combined in volume groups. Segments (logical volumes) are created from the

volume groups. The built-in volume manager handles all space allocation considerations involved

in file system creation.

Configuring file systems

You can configure your file systems to use the following features:

• Quotas. This feature allows you to assign quotas to individual users or groups, or to a directory

tree. Individual quotas limit the amount of storage or the number of files that a user or group

can use in a file system. Directory tree quotas limit the amount of storage and the number of

files that can be created on a file system located at a specific directory tree. See “Configuring

quotas” (page 25).

• Remote replication. This feature provides a method to replicate changes in a source file system

on one cluster to a target file system on either the same cluster or a second cluster. See “Using

remote replication” (page 127).

File system building blocks 11

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Hp StoreAll Storage User Manual Page 11