3.3.8. /proc/scsi/

3.3.8. /proc/scsi/

This directory is analogous to the /proc/ide/ directory, but it is for connected SCSI devices.

The primary file in this directory is /proc/scsi/scsi, which contains a list of every recognized SCSI device. From this listing, the type of device, as well as the model name, vendor, SCSI channel and ID data is available.

For example, if a system contains a SCSI CD-ROM, a tape drive, a hard drive, and a RAID controller, this file looks similar to the following:

Attached devices:  
Host: scsi1 
Channel: 00 
Id: 05 
Lun: 00   
Vendor: NEC      
Model: CD-ROM DRIVE:466 
Rev: 1.06   
Type:   CD-ROM                          
ANSI SCSI revision: 02 
Host: scsi1 
Channel: 00 
Id: 06 
Lun: 00   
Vendor: ARCHIVE  
Model: Python 04106-XXX 
Rev: 7350   
Type:   Sequential-Access                
ANSI SCSI revision: 02 
Host: scsi2 
Channel: 00 
Id: 06 
Lun: 00   
Vendor: DELL     
Model: 1x6 U2W SCSI BP  
Rev: 5.35   
Type:   Processor                        
ANSI SCSI revision: 02 
Host: scsi2 
Channel: 02 
Id: 00 
Lun: 00   
Vendor: MegaRAID 
Model: LD0 RAID5 34556R 
Rev: 1.01   
Type:   Direct-Access                    
ANSI SCSI revision: 02

Each SCSI driver used by the system has its own directory within /proc/scsi/, which contains files specific to each SCSI controller using that driver. From the previous example, aic7xxx/ and megaraid/ directories are present, since two drivers are in use. The files in each of the directories typically contain an I/O address range, IRQ information, and statistics for the SCSI controller using that driver. Each controller can report a different type and amount of information. The Adaptec AIC-7880 Ultra SCSI host adapter's file in this example system produces the following output:

Adaptec AIC7xxx driver version: 5.1.20/3.2.4 
Compile Options:   
TCQ Enabled By Default : Disabled   
AIC7XXX_PROC_STATS     : Enabled   
AIC7XXX_RESET_DELAY    : 5  
Adapter Configuration:            
SCSI Adapter: Adaptec AIC-7880 Ultra SCSI host adapter                            
Ultra Narrow Controller     PCI MMAPed 
I/O Base: 0xfcffe000  
Adapter SEEPROM Config: SEEPROM found and used.       
Adaptec SCSI BIOS: Enabled                     
IRQ: 30                    
SCBs: Active 0, Max Active 1, Allocated 15, HW 16, Page 255              
Interrupts: 33726       
BIOS Control Word: 0x18a6    
Adapter Control Word: 0x1c5f   
Extended Translation: Enabled 
Disconnect Enable Flags: 0x00ff      
Ultra Enable Flags: 0x0020  
Tag Queue Enable Flags: 0x0000 
Ordered Queue Tag Flags: 0x0000 
Default Tag Queue Depth: 8     
Tagged Queue By Device array for aic7xxx 
host instance 1:       {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}     
Actual queue depth per device for aic7xxx host instance 1:       {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
Statistics:   

(scsi1:0:5:0) Device using Narrow/Sync transfers at 20.0 MByte/sec, offset 15   
Transinfo settings: current(12/15/0/0), goal(12/15/0/0), user(12/15/0/0)   
Total transfers 0 (0 reads and 0 writes)              
		< 2K      2K+     4K+     8K+    16K+    32K+    64K+   128K+    
Reads:        0       0       0       0       0       0       0       0   
Writes:       0       0       0       0       0       0       0       0   

(scsi1:0:6:0) Device using Narrow/Sync transfers at 10.0 MByte/sec, offset 15   
Transinfo settings: current(25/15/0/0), goal(12/15/0/0), user(12/15/0/0)   
Total transfers 132 (0 reads and 132 writes)              
		< 2K      2K+     4K+     8K+    16K+    32K+    64K+   128K+    
Reads:        0       0       0       0       0       0       0       0   
Writes:       0       0       0       1     131       0       0       0

This output reveals the transfer speed to the SCSI devices connected to the controller based on channel ID, as well as detailed statistics concerning the amount and sizes of files read or written by that device. For example, this controller is communicating with the CD-ROM at 20 megabytes per second, while the tape drive is only communicating at 10 megabytes per second.


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