A physical disk may be connected to a logical disk, whereby it can be specified which lbn range of the physical disk to use. For example, we want to connect a device LDA1 to blocks 1000 through 20000 of a physical device: $ LD CONNECT DKA0: LDA1:/LBN=(START=1000,END=20999) Or we can specify a number of blocks to use: $ LD CONNECT DKA0: LDA1:/LBN=(START=1000,COUNT=20000) This will map lbn's 1000 through 20999 of DKA0: which can be accessed as a disk through LDA1: This functionality may also be used clusterwide by adding /SHARE. All nodes sharing a disk this way must specify the same parameters. Geometry is calculated by the driver and cannot be specified. Multiple ranges may be used for multiple LD devices, as long as there's no overlap. The range check is done on all cluster members. An example can be to partition a disk without any file structure on it: $ LD CONNECT DKA0: LDA1:/LBN=(START=0,COUNT=100000) $ LD CONNECT DKA0: LDA2:/LBN=(START=100000,COUNT=100000) $ LD CONNECT DKA0: LDA3:/LBN=(START=200000,COUNT=100000) $ LD CONNECT DKA0: LDA4:/LBN=(START=300000,COUNT=100000) This can also be shared: $ LD CONNECT DKA0: LDA5:/LBN=(START=400000,COUNT=100000)/SHARE In that case the partition can be accessed from other cluster members as well. Notice that the physical disk in question will be protected by a lock, and may not be mounted anywhere. A new locking protocol is in use between LDDRIVER's on different nodes in a cluster. The new V8.0 driver can deal with connected devices by old LDDRIVER's, old drivers however may not be able to connect to shared resources of the new drivers. If one driver is the first to connect to a resource it will establish the locking version in use. This means that if an old driver connects as the first one, the connection will work. Example: oldsys> ld connect d1 lda1/share/log %LD-I-CONNECTED, Connected $7$LDA1: to $8$DUA15:[LD]D1.DSK;1 (Shared) newsys> ld connect d1 lda1/share/log %LD-I-CONNECTED, Connected $7$LDA1: to $8$DUA15:[LD]D1.DSK;1 (Shared) (Old driver connected on other node) Notice that the new driver will tell us that an old driver has connected to the resource, and that an upgrade may be required. If the new driver connects first the old driver will issue a different error message: newsys> ld connect d1 lda1/share/log %LD-I-CONNECTED, Connected $7$LDA1: to $8$DUA15:[LD]D1.DSK;1 (Shared) oldsys> ld connect d1 lda1/share/log %LD-F-FILEINUSE, File incompatible connected to other LD disk in cluster This makes connection to a shared resource dependent on the order of the nodes where the connection occurs. For this reason it is advisable to install the new LD version on all nodes in a cluster if shared resources are used. The include file for the callable interface has changed. It used to be LD_DEFINES.H and is still included, but the new definitions are now in LDDEF.H created from and sdl source file. It is preferred to use the new definitions as they will become part of VMS in the future.