Hi All,
I am having few queries related to the Tagged Command Queuing(TCQ) in SCSI .
I am not clear whether this is the property of SCSI Devices or the adapter controller that is handing the device?
I am not clear whether this is the property of SCSI Devices or the adapter controller that is handing the device?
Is this can be changed or configured, if yes then how?
It would be nice if someone could please explain that what does term ?outstanding IO? means in SCSI device context. Is this same as tagged queue depth. HOw this is handled at SCSI driver?
How could this (TCQ) affect the disk throughput ?
I have tried to modify the TCQ as explained in aic79xx documentation.
I have added following line in file /etc/modprobe.conf
I have added following line in file /etc/modprobe.conf
options aic79xx aic 79xx=tag_info:{{64,64}} <- for target 0 and 1
But dmesg It is
still is queue depth is 4 (This is the same value as set in .config file CONFIG_AIC79XX_CMDS_PER_DEVICE)
Also it is explained in document that its default value is 32.
My system is having 2 SCSI hard disks discription is as given below.I am using linux kernel version 2.6.9 stock kernel.
# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: SEAGATE Model: ST39140W Rev: 1498
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: SEAGATE Model: ST39140W Rev: 1498
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi0 Channel: 00
Id: 01 Lun: 00
Vendor: COMPAQ Model: BD009222C7 Rev: B016
Type: Direct-Access ANSI SCSI revision: 02
Vendor: COMPAQ Model: BD009222C7 Rev: B016
Type: Direct-Access ANSI SCSI revision: 02
SCSI controller is
#lspci | grep ?storage controller?
00:08.0 SCSI storage controller: Adaptec ASC-29320A U320 (rev 10)
The low level SCSI driver is aic79xx.Here is dmesg output ( SCSI part ).
00:08.0 SCSI storage controller: Adaptec ASC-29320A U320 (rev 10)
The low level SCSI driver is aic79xx.Here is dmesg output ( SCSI part ).
#dmesg
SCSI subsystem initialized
ACPI: PCI interrupt 0000:00:08.0[A] -> GSI 11 (level, low) -> IRQ 11
scsi0 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev 1.3.11
<Adaptec 29320A Ultra320 SCSI adapter>
aic7901: Ultra320 Wide Channel A, SCSI Id=15, PCI 33 or 66Mhz, 512 SCBs
(scsi0:A:0): 40.000MB/s transfers (20.000MHz, 16bit)
(scsi0:A:1): 40.000MB/s transfers (20.000MHz, 16bit)
Vendor: SEAGATE Model: ST39140W Rev: 1498
Type: Direct-Access ANSI SCSI revision: 02
scsi0:A:0:0: Tagged Queuing enabled. Depth 4
SCSI device sda: 17783240 512-byte hdwr sectors (9105 MB)
SCSI device sda: drive cache: write back
sda: sda1 sda2 < sda5 sda6 sda7 >
Attached scsi disk sda at scsi0, channel 0, id 0, lun 0
Vendor: COMPAQ Model: BD009222C7 Rev: B016
Type: Direct-Access ANSI SCSI revision: 02
scsi0:A:1:0: Tagged Queuing enabled. Depth 4
SCSI device sdb: 17773524 512-byte hdwr sectors (9100 MB)
SCSI device sdb: drive cache: write back
sdb: sdb1
Attached scsi disk sdb at scsi0, channel 0, id 1, lun 0
ACPI: PCI interrupt 0000:00:08.0[A] -> GSI 11 (level, low) -> IRQ 11
scsi0 : Adaptec AIC79XX PCI-X SCSI HBA DRIVER, Rev 1.3.11
<Adaptec 29320A Ultra320 SCSI adapter>
aic7901: Ultra320 Wide Channel A, SCSI Id=15, PCI 33 or 66Mhz, 512 SCBs
(scsi0:A:0): 40.000MB/s transfers (20.000MHz, 16bit)
(scsi0:A:1): 40.000MB/s transfers (20.000MHz, 16bit)
Vendor: SEAGATE Model: ST39140W Rev: 1498
Type: Direct-Access ANSI SCSI revision: 02
scsi0:A:0:0: Tagged Queuing enabled. Depth 4
SCSI device sda: 17783240 512-byte hdwr sectors (9105 MB)
SCSI device sda: drive cache: write back
sda: sda1 sda2 < sda5 sda6 sda7 >
Attached scsi disk sda at scsi0, channel 0, id 0, lun 0
Vendor: COMPAQ Model: BD009222C7 Rev: B016
Type: Direct-Access ANSI SCSI revision: 02
scsi0:A:1:0: Tagged Queuing enabled. Depth 4
SCSI device sdb: 17773524 512-byte hdwr sectors (9100 MB)
SCSI device sdb: drive cache: write back
sdb: sdb1
Attached scsi disk sdb at scsi0, channel 0, id 1, lun 0
TIA
Satinder
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