关于solaris下面的CnTnDnSn里面的Tn和Dn

chao_ping

一直没有搞清楚,这个Tn究竟代表什么含义.
Tn和Dn有什么区别.
好像看介绍都是Target ID,一般一个SCSI卡上面,一个Scsi ID只能连接一个硬盘吧? 干吗还有Tn和Dn的区别呢?

clu65

Cn means controller No.
Tn means target No. You can attach 7  SCSI devices with target 0-6 (target 7 is for controller itself, though it can be changed) to one single channel SCSI controller adapter and 15 SCSI devices with target 0-6 and 8-15 to dual channel SCSI controller adapter. For Multipak, D1000, A5X00 Disk array the target No of a hard disk depends on the slot no it is located.
Dn called LUN(Logical Unit No). It is always zero for no hardware-RAID devices. However for Hardware RAID disk array A1000, A3X00, T3, the Lun of the hard driver you see from OS may not be zero.

Hope this may help.

chao_ping

thanks.
This means for general scsi disks, the Tn means it is the nth disk in this scsi card
while for hardware-based raid , from the os view, the logical disk(made up of several disks) is expressed with the combination of Tn and Dn.
Is it right.
Thanks.

clu65

Not exactly.

For example, the Sun StorEdge MultiPack storage system has two sets of pre-selected SCSI IDs. The user can choose to use IDs 1, 2, 3, 4, 5, and 6 or IDs 9, 10, 11, 12, 13, and 14. A switch allows customers to select IDs 1—6 or IDs 9—14, allowing daisy-chaining of Sun StorEdge MultiPack systems on a fast/wide SCSI bus.

When you daisy chain the external SCSI devices to SCSI adapter, vendor usually has jupmer on the back of the device you can pick target ID you want just to make sure it will not conflict with other device. Of course you usually set the target ID of tape device to 6 so it gets higher priority.

Hope this answers your question.

oramind

最初由 chao_ping 发布
[B]thanks.
This means for general scsi disks, the Tn means it is the nth disk in this scsi card
while for hardware-based raid , from the os view, the logical disk(made up of several disks) is expressed with the combination of Tn and Dn.
Is it right.
Thanks. [/B]

what\'s important is not the order of disks in a daisy-chain, but the scsi id set on each disk.  kind of like the idea of an ip address on an ethernet lan.

btw, clu65\'s explaination is very clear.