Available size of a disk
Within the physical disk area, the capacity available for creating volumes equals the physical disk size rounded down to the cylinder boundary, minus the private slice size. This size is called the available size of disk.
Size of a private slice
Private slice is an area that GDS reserves on each disk for storing data, such as configuration information and the JRM log.
When a physical disk is registered with a class, a private slice is reserved. Disks within the same class will all have the same private slice size. In the shared class and the local class, the size of a private slice in the class is determined by the size of the disk that is first registered with the class.
The size of a private slice can be estimated as below. Below estimate values represent the maximum size of the private slice that is reserved in the physical disk. The private slice size never exceeds the estimated values.
In the root class [EFI]
10.5 MB
In the shared class and the local class
When the size of the disk first registered with the class is 10 GB and below:
32 MB
When the size of the disk first registered with the class is over 10 GB:
32 MB + (0.1% of the disk capacity to the cylinder boundary, rounded-up)
The size of a log for JRM is determined by the size of the volume. As a result, the log area for JRM may not be reserved because the private slice size becomes insufficient when a mirror volume or netmirror volume is created after registering a disk larger in size than the first registered disk with the class. Therefore, the following points should be considered when registering the disk to the class.
When creating a mirror volume
When the JRM log area for the volume cannot be reserved, JRM cannot be used for the volume. Therefore you are recommended to first register a disk of the maximum size with the class.
When creating a netmirror volume
When the JRM log area cannot be reserved, a netmirror volume cannot be created.
In a class where a netmirror volume is created, you are recommended to first register a disk of the maximum size with the class.
When physical disks are registered with shadow classes, the sizes of private slices are determined based on the values stored in their private slices. For this reason, regardless of the order of registering physical disks with shadow classes, the sizes of private slices of the shadow classes become consistent with those of the corresponding disk classes. In other words, the order of registering physical disks with shadow classes is not a cause for concern.
Cylinder size
The cylinder size of a disk registered with a local class or a shared class is 32,768 blocks (= 16 MB). To calculate the sizes of disks to register with local classes or shared classes, assume that the cylinder size is 16 MB.
1 TB or larger disks [4.3A10 or later]
In the following environments, 1 TB or larger disks can be managed in local and shared classes.
When using GDS 4.3A20 or later in a RHEL6 (Intel64) environment, or a RHEL7(Intel64) or later environment
When using GDS 4.3A10 in a RHEL6 (Intel64) environment and performing the following settings
Apply the following patches:
T005774LP-05 or later (FJSVsdx-bas)
T006424LP-02 or later (devlabel)
T005775LP-04 or later (kmod-FJSVsdx-drvcore)
T006319LP-02 or later (FJSVsdx-drv)
Describe SDX_EFI_DISK=on in the GDS configuration parameter file /etc/opt/FJSVsdx/sdx.cf.
Reboot the system.
For the patch application method and details on the configuration parameter SDX_EFI_DISK, see the Update Information Files of the patch T005774LP-05 or later.
For the cluster system, the settings above need to be performed on all nodes.
For 1 TB or larger disks, register disks with the class where the disk label type is GPT and manage them. For details, see "2.3.8 Disk Label."
