Tomonari Horikoshi
2007-Aug-01 10:09 UTC
[Xen-devel] [RFC] To promote PV SCSI posted before ...
Hi all.
To promote PV SCSI posted before, I post this patch.
http://lists.xensource.com/archives/html/xen-devel/2007-07/msg00450.html
http://lists.xensource.com/archives/html/xen-devel/2007-07/msg00451.html
http://lists.xensource.com/archives/html/xen-devel/2007-07/msg00452.html
http://lists.xensource.com/archives/html/xen-devel/2007-07/msg00453.html
http://lists.xensource.com/archives/html/xen-devel/2007-07/msg00561.html
PV SCSI has the structure like VBD.
Frontend driver is registered as SCSI HBA driver by Guest OS,
it passes SCSI CDB as is by using RING.
Frontend driver accesses all disks connected with 1HBA of Dom0.
Now, the whole of 1HBA of Dom0 is used by the guest
but in the future, 1HBA will be able to be shared with some Guest OS by NPIV.
(see, http://www.xensource.com/files/xensummit_4/Xen_Summit_8_Matsumoto.pdf)
I activated some SCSI devices( tape drive, media changer) by using
this PV-on-HVM(PV SCSI). So Guest domain can backup data to tape
directly. And Guest domain works as a Backup Server by this function．
* LTO Tape Library ( Ultrium 2 drive of FC )
# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: HP Model: Ultrium 2-SCSI Rev: F45H
Type: Sequential-Access ANSI SCSI revision: 03
Host: scsi0 Channel: 00 Id: 00 Lun: 01
Vendor: HP Model: Ultrium 2-SCSI Rev: F45H
Type: Sequential-Access ANSI SCSI revision: 03
* DAT Library (SCSI)
# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 02 Id: 00 Lun: 00
Vendor: LSI Model: MegaRAID SAS RMB Rev: 1.02
Type: Direct-Access ANSI SCSI revision: 05
Host: scsi6 Channel: 00 Id: 00 Lun: 00
Vendor: HP Model: C7438A Rev: ZU68
Type: Sequential-Access
The performance of PVSCSI is almost the same as VBD.
The following value is a performance ratio of pvscsi and vbd.
( pv-scsi/vbd )
random read:write=1:1 3disk 1prosecs/1disk
blksize = 8k 1.00
blksize = 128k 1.00
random read:write=1:1 3disk 5prosecs/1disk
blksize = 8k 1.08
blksize = 128k 1.15
sequential blksize=128k 1prosecs/1disk
read = 0.85
write = 0.93
Best regards,
Horikoshi
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