Ldev 1 Disk Space Report

Support for using entire disk space on LDEV 1
By Ushadevi H N, Commercial Systems Division
Beginning with MPE/iX 7.5 release, the MPE/iX operating system uses the full capacity of the disk configured as LDEV 1.
This article explains the enhancement and briefly describes the user level changes of which customers need to be aware to
use the system appropriately after installing MPE/iX 7.5 release.
Background
Before this release, even if the actual capacity of the disk was more than 4GB (such as 18GB) and it was configured as
LDEV 1, MPE/iX limited the access to only 4GB of the total disk space and rest of the disk was unavailable for use.
Primarily, this limitation existed due to the fact that the initial system loader (ISL> prompt) can access only the first 4GB of
the disk and hence system utilities such as START, DUMP, DISKUTIL, etc. need to reside in the first 4GB of the disk.
Therefore, LDEV 1 disk access was limited to 4GB of the disk space.
With this enhancement, even though the ISL limitation is not removed (system utilities need to be stored within the first 4GB
of the disk), the operating system has now been enhanced to handle the entire disk space for storing other files.
Hardware and Software requirements
This enhancement is provided and enabled by default once the MPE 7.5 version of the operating system (Release C.75.00) is
installed.
This feature works with all HP supported disks and disk arrays irrespective of the disk capacity. This new feature is enabled
for all the LDEV 1 disks with a disk capacity more than 5GB. Note: Even though this feature is to support all disks greater
than 4GB, due to the operating system internal overhead involved in supporting this feature, it is only enabled for disks with
a capacity more than 5GB.
Enhancement Details
This enhancement distinguishes between files residing within 4GB and those beyond 4GB for disks configured as LDEV 1.
As stated previously, for the proper functioning of the MPE/iX operating system, it is very critical that some of the system
utilities reside in the first 4GB of the disk. Therefore, user files targeted for LDEV 1 will only be stored in the first 4GB
under two circumstances: if there is not enough space beyond the first 4GB to accommodate the file OR when forced by the
file equate option described below.
It is highly recommended that user files are kept in the disk space beyond 4GB, to preserve space for system files now and in
the future. A process is provided to differentiate and help users keep files within or beyond 4GB.
;DEV=**$SYSTEM_MASTER
In the file commands such as BUILD and FILE, file system intrinsics such as HPFOPEN, using
$SYSTEM_MASTER refers
to the first 4GB of LDEV 1 and files will be referenced/stored within this space.
WARNING: In case the requested space is not available within the 4GB, an error indicating out of space will be returned
(even if enough space is available beyond the first 4GB) when creating this file.
OUT OF DISK SPACE (FSERR 46)
To make more space within 4GB,
Read
the section
“
Freeing up Space within 4GB
”
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Full Disk Space on LDEV 1
7/18/2008
http://jazz.external.hp.com/papers/ldev_1.htm