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HP StorageWorks Scalable File Share User Manual

Page 91

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Creating a file system — EVA4000 storage

5–7

14 4 B ost 290 south[5-6] -
15 5 A ost 290 south[5-6] -
16 5 B ost 290 south[5-6] -
.

.

.

You must select preferred servers so that OST serving is balanced optimally. Both of the servers in a server

pair are capable of serving (that is, being the preferred server for) any of the LUNs on the arrays attached

to the server. In the example above, LUNs 8 through 11 are visible to (that is, presented to) the

south3

and

south4

servers. This means that either of these servers could be the preferred server for any of LUNs 8

through 11. However, it would not be optimal to prefer all of the LUNs to one of the servers, as this would

leave the second server unused. To help you to balance the distribution of LUNs to servers, the

create

filesystem

command shows the EVA4000 controller that is managing each LUN.

The HP SFS system is configured with multiple paths between a server and the EVA4000 array. Each host

has two HBA ports. Each HBA port is connected by a separate Fibre Channel fabric to both EVA4000

controllers. This means that each server has four paths to a given LUN.

However, when you create a LUN, you specify the preferred EVA4000 controller for the LUN (refer to

Chapter 5 of the HP StorageWorks Scalable File Share System Installation and Upgrade Guide for more

information). In the example above, LUNs 8 and 9 are being managed by different EVA4000 controllers.

This is normal; however, if LUNs 8 and 9 were both managed by the same EVA4000 controller, you would

need to investigate the configuration and make changes if necessary. Specifically, if LUNs 8 and 9 were

both preferred to the

south3

server, the

south3

server would access both LUNs through the same

controller port and the second EVA4000 controller would be idle. This would impact performance.

For examples of file system configurations, see Appendix C.

For information on how to order OST services in the file system to support optimal performance, see

Section 5.1.4.1.

File system optimization for I/O pattern

You can optimize I/O operations on the OST services in a file system by specifying the file I/O pattern that

you expect on the file system. The options are:

Predominantly large file streamed sequential access

Large numbers of smaller files

Select the scenario that best suits your needs. If you choose the second option (large numbers of small files),

the

mballoc

option is added to the list of options that can be specified for OST services (this list is presented

later).

Mount options

Underlying the OST and MDS services on the Lustre file systems, there are

ldiskfs

file systems. When an

OST or MDS service starts, it mounts the underlying

ldiskfs

file system so that it can access the data. You

can specify mount options on the file system services to determine what happens when the file systems are

mounted.

When creating a file system, accept the default options provided by the

create filesystem

command for OST services.

You can optionally set the

acl

and

user_xattrs

options for MDS services:

The

acl

option must be enabled if Access Control Lists (ACLs) are to be used when the file

system is mounted on client nodes.

The

user_xattrs

option must be enabled if extended attributes are to be used when the file

system is mounted.