1 CREATE 2 DISK Create or modify a virtual disk, memory disk, of a specified capacity in local private memory or Galaxy shared memory. Format CREATE DISK disk-name 3 Parameters disk-name The name of the memory disk that you want to create or modify. The disk name must begin with MD followed by a controller letter between A and Z followed by the disk number from 0 to 9999 for served devices such as MDC256. The non-served device number limit is 32767. 3 Description The CREATE DISK command creates or modifies a memory disk in local private memory or Galaxy shared memory The command can be further refined with the available qualifiers. The command can be entered from the VMS prompt or the DECRAM> prompt. Requires AUDIT, CMKRNL, SYSLCK, SYSPRV, and PHY_IO privileges. 3 Qualifiers /CAPACITY /CAPACITY=blocks This qualifier is required. You must specify the size of the memory disk to create or modify in blocks (512 bytes). Capacity=0 will return the memory to the operating system. /MEMORY /MEMORY=type This qualifier is not required and defaults to local. LOCAL means create the memory disk in local private memory. SHARED means create the memory disk in Galaxy shared memory. Local memory can be accessed on only the node or instance where it resides. Shared memory can be accessed from any Galaxy instance that attaches to the shared memory. Shared memory requires VMS Galaxy software to be loaded and running. /PERSIST /[no]PERSIST This qualifier is not required and defaults to /PERSIST. It controls whether or not the disk is restored after a reboot. Note that /nopersist and /serve are mutually exclusive. /SERVE /[no]SERVE This qualifier is not required and defaults to /NOSERVE. It controls whether or not disk serving is available for the VMSCluster. When /SERVE is selected, the disk is MSCP served. Once a disk is selected /SERVE it cannot be selected /NOSERVE. Note that /nopersist and /serve are mutually exclusive. Also note that served device numbers cannot exceed 9999. /ALLOCLASS /ALLOCLASS=number This qualifier is not required and defaults to 99. It is only allowed for SHARED memory type disks. Note that associating a particular controller letter with a specific allocation class is valid for all time! All time means as long as the shared memory section exists or the MDRECOVER.DAT file exists. Selecting an allocation class equal to the node's allocation class for shared memory disks is not allowed. /WRITEBUFFERED /[no]WRITEBUFFERED This qualifier is not required and defaults to /NOWRITEBUFFERED. It is selected to help reduce write recovery time after a power fail or system crash. Application recovery techniques and OpenVMS Volume Shadowing can also be used to reduce write recovery time after a power fail. /RAD /RAD=stripe (default) /RAD=number /RAD=home /RAD=(,,,) This qualifier is not required and defaults to striping the memory disk across all available RADs for local and shared disks. It is only effective when RAD SUPPORT is enabled on the system. It is used to specify a single RAD (i.e., a number such as 2) for both local and shared memory, or a comma separated list of RADs for shared memory only. It can also be used to select the home RAD or to change from a single RAD to striping. 3 Examples 1. $ decram create disk mdf1111 /capacity=16777216 /memory=local - /serve /nopersist /rad=2 This example creates an 8 gigabyte memory disk mdf1111 in local memory with an allocation class equivalent to the node allocation class. It is issued from the VMS prompt. It will not persist at the next reboot but disk serving to the VMScluster is enabled. If the system has RAD SUPPORT enabled then RAD 2 will be used to create the disk otherwise OpenVMS will pick the RAD(s). 2. DECRAM> create disk mda0 /cap=1000034 /mem=shared /rad=(0,1) This example creates memory disk $99$mda0 in shared memory RAD 0 and RAD 1 with a size of 1,000,034 blocks and allocation class 99. It is issued from the DECRAM> prompt. It will persist at the next reboot but disk serving to the VMScluster is not enabled. 3. DECRAM> create disk mdb0 /cap=10000 /mem=shared /alloc=13 DECRAM> create disk mdb1 /cap=10000 /mem=shared /alloc=13 $ init $13$mdb0 $13$mdb0 $ mount dsa0: /shadow=($13$mdb0:,$13$mdb1:) $13$mdb0 This example creates two 10000 block shared memory disks with allocation class 13. One of them is initialized and a VMS Volume shadow set is made from the two memory disks. The memory disks are not served to the cluster. 4. VMS Galaxy Instance 0 $ decram create disk mdb0 /capacity=10000 /memory=shared $ init mdb0 mdb0 $ mount /cluster mdb0 mdb0 $ show device mdb0 Device Device Error Volume Free Trans Mnt Name Status Count Label Blocks Count Cnt $99$MDB0: (BANG) Mounted 0 MDB0 9967 1 2 VMS Galaxy Instance 1 $ decram create disk mdb0 /capacity=10000 /memory=shared $ show device mdb0 Device Device Error Volume Free Trans Mnt Name Status Count Label Blocks Count Cnt $99$MDB0: (BIG1) Mounted 0 MDB0 9967 1 2 This example assumes a two instance VMS Galaxy with DECRAM V3 installed on both instances. It creates two 10000 block shared memory disks with allocation class 99. One of them is created on instance 0 and the other on instance 1. The shared disk is initialized and mounted cluster-wide from instance 0. Note that if a shared disk has been created on each instance the "$ decram create disk" command is only necessary on one instance.