Meaning behind target ID in the output of camcontrol and MegaCli

[Pallav Bose]

Hi,

I have a Dell PowerEdge R730 with a PERC H730 and a PERC H830. The H730 is connected to 15 disks and the H830 to two disks, with a RAID 0 configuration created out of each disk. The mrsas(4) driver is attached to each RAID controller.

# MegaCli cfgdsply aall | grep -e Slot -e Target -e RAID -e Adapter
Adapter: 0

Product Name: PERC H730 Mini

Virtual Drive: 0 (Target Id: 0)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 0
Virtual Drive: 1 (Target Id: 1)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 1
Virtual Drive: 2 (Target Id: 2)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 2
Virtual Drive: 3 (Target Id: 3)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 3
Virtual Drive: 4 (Target Id: 4)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 4
Virtual Drive: 5 (Target Id: 5)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 5
Virtual Drive: 6 (Target Id: 6)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 6
Virtual Drive: 7 (Target Id: 7)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 7
Virtual Drive: 8 (Target Id: 8)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 8
Virtual Drive: 9 (Target Id: 9)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 9
Virtual Drive: 10 (Target Id: 10)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 10
Virtual Drive: 11 (Target Id: 11)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 11
Virtual Drive: 12 (Target Id: 12)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 12
Virtual Drive: 13 (Target Id: 13)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 13
Virtual Drive: 14 (Target Id: 14)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 14

Adapter: 1

Product Name: PERC H830 Adapter

Virtual Drive: 0 (Target Id: 0)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 0
Virtual Drive: 1 (Target Id: 1)
RAID Level          : Primary-0, Secondary-0, RAID Level Qualifier-0
Slot Number: 1

How is the target ID determined? Where is this information stored? Under what circumstances can it change?

My understanding is that the target ID links a disk in a particular slot on a particular adapter to its device name. This can be gathered from the MegaCli configuration output above and the camcontrol output below. MegaCli gives us the 3-tuple [adapter,slot,target ID] and camcontrol gives us the 3-tuple [adapter,target ID,device name]. So, I now know what device name does a physical disk (configured as a RAID 0) in a particular slot on a particular adapter map to.

Is my understanding correct?

# camcontrol devlist
<DELL PERC H730 Mini 4.25>         at scbus0 target 0 lun 0 (pass0,da0)
<DELL PERC H730 Mini 4.25>         at scbus0 target 1 lun 0 (pass1,da1)
<DELL PERC H730 Mini 4.25>         at scbus0 target 2 lun 0 (pass2,da2)
<DELL PERC H730 Mini 4.25>         at scbus0 target 3 lun 0 (pass3,da3)
<DELL PERC H730 Mini 4.25>         at scbus0 target 4 lun 0 (pass4,da4)
<DELL PERC H730 Mini 4.25>         at scbus0 target 5 lun 0 (pass5,da5)
<DELL PERC H730 Mini 4.25>         at scbus0 target 6 lun 0 (pass6,da6)
<DELL PERC H730 Mini 4.25>         at scbus0 target 7 lun 0 (pass7,da7)
<DELL PERC H730 Mini 4.25>         at scbus0 target 8 lun 0 (pass8,da8)
<DELL PERC H730 Mini 4.25>         at scbus0 target 9 lun 0 (pass9,da9)
<DELL PERC H730 Mini 4.25>         at scbus0 target 10 lun 0 (pass10,da10)
<DELL PERC H730 Mini 4.25>         at scbus0 target 11 lun 0 (pass11,da11)
<DELL PERC H730 Mini 4.25>         at scbus0 target 12 lun 0 (pass12,da12)
<DELL PERC H730 Mini 4.25>         at scbus0 target 13 lun 0 (pass13,da13)
<DELL PERC H730 Mini 4.25>         at scbus0 target 14 lun 0 (pass14,da14)
<DELL PERC H830 Adp 4.25>          at scbus2 target 0 lun 0 (pass15,da15)
<DELL PERC H830 Adp 4.25>          at scbus2 target 1 lun 0 (pass16,da16)
<Kingston DataTraveler 3.0 PMAP>   at scbus4 target 0 lun 0 (da17,pass17)

I haven't tried any other configuration apart from RAID 0.

Regards,Pallav