Virtual SCSI (Small Computer Systems Interface) adapters provide one partition with the ability to use storage I/O (disk, CD, and tape) that is owned by another partition.
A Virtual SCSI client adapter in one logical partition can communicate with a Virtual SCSI server adapter in another partition. The Virtual SCSI client adapter allows a logical partition to access a storage device being made available by the other logical partition. The partition owning the hardware is the server partition, and the partition that uses the virtualized hardware is the client partition. With this arrangement, the system can have many server partitions.
For example, partition A provides disk space to partitions B, C, and D. A partition can simultaneously use virtual I/O from more than one partition. Therefore, using the example, while partition A provides disk space to partitions B, C, and D, partitions A and B can use a tape drive connected to partition D. In this case, A is serving D for disk space, while D is serving A for the tape device.
Virtual SCSI allows you to simplify the backup and maintenance operations on your managed system. When you back up the data on the server partition, you also back up the data on each client partition.
Virtual SCSI server adapters can be created only in partitions of type i5/OS® and Virtual I/O Server.
Disk unit, CD/DVD, and tape on an IBM® System i® model are based on the SCSI protocol using the ANSI SCSI Remote DMA (Direct Memory Access) protocol. Therefore, Linux® partitions can access data among each other or by an adapter that is directly attached to the memory of other partitions.
The virtual SCSI client device driver is not capable of storage protection using Redundant Arrays of Independent Disks (RAID). While the Linux operating system allows software RAID protection of virtual disks, the recommended technique for protecting disk storage is to configure the virtual I/O storage server to perform the disk protection.
Different partitioning tools assign virtual SCSI adapters to logical partitions in different ways. For more information about virtual SCSI adapter assignment by a specific partitioning tool, see Partitioning tools.
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