Features/SCSI: Difference between revisions

Revision as of 17:05, 30 September 2011

Summary

Improving the SCSI subsystem lays the ground for a more flexible and scalable virtual storage architecture.

Owner

Name: Paolo Bonzini
Email: pbonzini@redhat.com

Description

Shortcomings of virtio-blk include a small feature set (requiring frequent updates to both the host and the guests) and limited scalability. Both of these problems can be improved, while preserving virtio-blk's high performance, by basing a next-generation virtual storage architecture on the SCSI command set.

As a prerequisite for implementing the virtio SCSI HBA, several improvements were necessary in the SCSI subsystem of QEMU.

Status

The following improvements were done to the SCSI subsystem:

Improved (and less buggy) modeling of SCSI requests
Flexible SCSI addressing (channel/target/LUN)
Improved consistency with the SCSI specifications (SAM, SPC, SBC)
Improved support for emulated SCSI CD-ROM drives (MMC)
Migration support

Links

git tree (branch scsi-addr)
William Cohen's SystemTap scripts for QEMU

@@ Line 10: / Line 10: @@
 == Description ==
-Light-weight logging at points of interest inside QEMU can improve common debugging and performance analysis tasks.  Currently the QEMU community has to rely on debuggers, which may be invasive and slow, or printfs, which are not suited for high-frequency logging.
+Shortcomings of virtio-blk include a small feature set (requiring frequent updates to both the host and the guests) and limited scalability.  Both of these problems can be improved, while preserving virtio-blk's high performance, by basing a next-generation virtual storage architecture on the SCSI command set.
-As a prerequisite for implementing a virtio SCSI HBA, several improvements were necessary in the SCSI subsystem of QEMU.
+As a prerequisite for implementing the virtio SCSI HBA, several improvements were necessary in the SCSI subsystem of QEMU.
 == Status ==