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Creating partitioned files on virtual disks – HP Integrity NonStop J-Series User Manual

Page 57

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Configuring and Managing SMF Processes

HP NonStop Storage Management Foundation User's Guide523562-007

3-7

Considerations for Data

Data that must be accessible from OSS through its /G interface. This restriction
does not apply for H06.26, J06.15, or later RVUs.

Data that must be network accessible from a remote system running a version of
the operating system prior to D38

Files with large labels that cannot be converted (see

Expanding File Labels

on

page 4-6)

Data that should be left directly accessible for performance or operational reasons
includes:

Program files where application start-up time is critical

Data that must be backed up by using volume mode backup (see

Section 7, File

Protection and Recovery for Virtual Disks

)

Data can also be left directly accessed to reduce the overall size of the SMF
configuration. For example, a 500 GB SQL table must be split into partitions of no more
than 2 GB each, resulting in 250 partitions. Under SMF, each partition requires a virtual
disk process. If only 8 CPUs are available for SMF use, more than 30 VDPs per CPU
will have to be configured. This number can be reduced by leaving one partition per
disk directly accessed. Further, if the system uses 8 GB drives, four SQL partitions can
be placed on each drive. If one of these partitions remains directly accessed, the
number of VDPs will be reduced by 25 percent. Another alternative to reduce the
overall size of the SMF configuration is to identify disks full of static data and leave
them directly accessed.

Creating Partitioned Files On Virtual Disks

In a situation where all the partitions reside on the physical disks, there is a risk of
losing one partition in case one physical disk fails. This is not the case in a system that
has some partitions residing on physical disks and some on virtual disks.

When a partitioned file resides on a virtual disk, two scenarios are possible:

The primary partition is on a physical disk. Some of its secondary partitions reside
on physical disks and some reside on virtual disks.

The primary partition is on a virtual disk. Some of its secondary partitions reside on
physical disks and some reside on virtual disks.

In the first case only, there is a risk of losing more than one partition if a physical disk
fails. If a secondary partition on a physical disk and the physical file corresponding to a
secondary partition on a virtual disk happen to be on the same physical disk, and that
disk fails, two partitions will be lost. HP suggests that you do not place the physical file
(which corresponds to a secondary partition on a virtual disk) on a physical disk that
already has a secondary partition. Use the PHYSVOL option to place the physical file
on the appropriate physical disk.

The following example demonstrates this:

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