Design of a Cluster Logical Volume Manager updated

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Logical volume device driver:
It is a pseudo-device driver that manages and processes all I/O and operates on logical volumes through the /dev/lv  special file. It translates logical addresses into physical addresses and sends I/O requests to specific device drivers. Like the physical disk device driver, this pseudo-device driver provides character and block entry points with compatible arguments. Each volume group has an entry in the kernel device switch table. Each entry contains entry points for the device driver and a pointer to the volume group data structure. The logical volumes of a volume group are distinguished by their minor numbers.

Disk Device Drivers:
There are various disk device drivers in LVM. The most common disk device driver is the one for SCSI device drivers: scdisk and csdiskpin (in /usr/lib/drivers). The second most common disk device driver is most often the one for Serial Storage Architecture (SSA) disks [23].
Small Computer System Interface (SCSI) [24] disk device drivers support the SCSI fixed disk, CD-ROM (compact disk read only memory), and read/write optical (optical memory) devices. Typical fixed disk, CD-ROM, and read/write optical drive operations are implemented using the open, close, read, write, and ioctl subroutines.
SSA disk drives are represented in AIX as SSA logical disks (hdisk0, hdisk1….hdiskN) and SSA physical disks (pdisk0,pdisk1.....pdiskN). SSA RAID arrays are represented as SSA logical disks (hdisk0, hdisk1.....hdiskN). SSA logical disks represent the logical properties of the disk drive or array and can have volume groups and file systems mounted on them. SSA physical disks represent the physical properties of the disk drive.

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