HP StorageWorks Scalable File Share System Installation and Upgrade Guide Version 2.2

Assigning roles to servers 2–27
2.8 Assigning roles to servers
NOTE: Use the worksheet in Table B-7 in Appendix B to record the information you gather in this section.
Within an HP SFS system, various servers are responsible for running specific services, as follows:
Administration The administration service allows you to configure and operate the HP SFS
system and to configure the file systems served by the HP SFS system. The
server the administration service runs on is referred to as the administration
server.
Meta-data Server The meta-data server (MDS) service provides meta-data services for file
systems. The server the MDS service runs on is referred to as the MDS server.
Object Storage Target Object Storage Target (OST) services provide object storage services for file
systems. Servers that run only OST services are referred to as Object Storage
Servers.
In deciding how to map these services to specific servers, consider the following points:
• Hardware support for high availability.
EVA4000 and SFS20 storage arrays support high availability. In such a configuration, servers are
grouped in pairs (server pairs). Each server in a server pair is able to run the services of the other
server if that server fails.
• The administration service normally runs on the first server. The administration service can run on (that
is, fail over to) the MDS server.
• The MDS service normally runs on the second server. The MDS service can run on (that is, fail over to)
the administration server.
• The Lustre file system is a parallel file system, which means that file operations can be performed over
several OST services at the same time. OST services can run on the servers that run the MDS and
administration services. However, if an OST service and an MDS service both run on the same server,
they may impact each other’s performance and responsiveness.
Table 2-10 shows some example mappings of services to servers.
Table 2-10 Server/services mapping examples
Number of
Servers
Distribution of Services
Server 1Server 2Server 3Server 4Server 5Server 6
(a) 2 servers
1
1. Configurations a and b do not usually apply in systems where SFS20 storage is used.
OST1
OST2
Administration
service
OST3
OST4
MDS service
N/A N/A N/A N/A
(b) 4 servers
1
OST1
OST2
Administration
service
OST3
OST4
MDS service
OST5
OST6
OST7
OST8
N/A N/A
(c) 4 servers Administration
service
MDS service OST1
OST2
OST3
OST4
N/A N/A
(d) 6 servers Administration
service
MDS service OST1
OST2
OST3
OST4
OST5
OST6
OST7
OST8