Nedostatečný výkon pevného disku v systému s řadičem Adaptec SCSI

Supportní databáze (jsj_adaptec_performance_70)

SuSE Linux: Do verze (včetně) 7.0

Symptomy:

Příčina:

CONFIG_AIC7XXX_TCQ_ON_BY_DEFAULT
This option causes the aic7xxx driver to attempt to use tagged command
queueing on any devices that claim to support it.  If this is set to yes,
you can still turn off TCQ on troublesome devices with the use of the
tag_info boot parameter.  See /usr/src/linux/drivers/scsi/README.aic7xxx
for more information on that and other aic7xxx setup commands.  If this
option is turned off, you may still enable TCQ on known good devices by
use of the tag_info boot parameter.

If you are unsure about your devices then it is safest to say N here.

However, TCQ can increase performance on some hard drives by as much
as 50% or more, so I would recommend that if you say N here, that you
at least read the README.aic7xxx file so you will know how to enable
this option manually should your drives prove to be safe in regards
to TCQ.

Conversely, certain drives are known to lock up or cause bus resets when
TCQ is enabled on them.  If you have a Western Digital Enterprise SCSI
drive for instance, then don't even bother to enable TCQ on it as the
drive will become unreliable, and it will actually reduce performance.

Řešení:

 zgrep TCQ /proc/config.gz

V SuSE Linuxu 7.0 s původním jádrem by měl obsahovat následující:

# CONFIG_AIC7XXX_TCQ_ON_BY_DEFAULT is not set

CONFIG_AIC7XXX_TCQ_ON_BY_DEFAULT=y

         "aic7xxx=tag_info:{{8,8..},{8,8..},..}"

 This option is used to disable or enable Tagged Command Queueing
 (TCQ) on specific devices.  As of driver version 5.1.11, TCQ is now
 either on or off by default according to the setting you choose
 during the make config process.  In order to en/disable TCQ for
 certian devices at boot time, a user may use this boot param.  The
 driver will then parse this message out and en/disable the specific
 device entries that are present based upon the value given. The
 param line is parsed in the following manner:


   { - first instance indicates the start of this parameter values
           second instance is the start of entries for a particular
           device entry
   } - end the entries for a particular host adapter, or end the
           entire set of parameter entries
   , - move to next entry.  Inside of a set of device entries, this
           moves us to the next device on the list.  Outside of device
           entries, this moves us to the next host adapter
   . - Same effect as , but is safe to use with insmod.
   x - the number to enter into the array at this position.
           0 = Enable tagged queueing on this device and use the
           default queue depth
           1-254 = Enable tagged queueing on this device and use this
                   number as the queue depth
           255 = Disable tagged queueing on this device.
           Note: anything above 32 for an actual queue depth is
           wasteful and not recommended.

 A few examples of how this can be used:

 tag_info:{{8,12,,0,,255,4}}

   This line will only effect the first aic7xxx card registered.  It
   will set scsi id 0 to a queue depth of 8, id 1 to 12, leave id 2
   at the default, set id 3 to tagged queueing enabled and use the
   default queue depth, id 4 default, id 5 disabled, and id 6 to 4.
   Any not specified entries stay at the default value, repeated
   commas with no value specified will simply increment to the next
   id without changing anything for the missing values.


 tag_info:{,,,{,,,255}}

   First, second, and third adapters at default values.  Fourth
   adapter, id 3 is disabled.  Notice that leading commas simply
   increment what the first number effects, and there are no need for
   trailing commas.  When you close out an adapter, or the entire
   entry, anything not explicitly set stays at the default value.

 A final note on this option.  The scanner I used for this isn't
 perfect or highly robust.  If you mess the line up, the worst that
 should happen is that the line will get ignored.  If you don't close
 out the entire entry with the final bracket, then any other aic7xxx
 options after this will get ignored.  So, in general, be sure of
 what you are entering, and after you have it right, just add it to
 the lilo.conf file so there won't be any mistakes.  As a means of
 checking this parser, the entire tag_info array for each card is now
 printed out in the /proc/scsi/aic7xxx/x file.  You can use that to
 verify that your options were parsed correctly.

Pokud je součástí jádra ovladač aic7xxx, můžete vložit parametr při startu pomocí "append" řádky do souboru /etc/lilo.conf (nezapomeňte poté, co provedete všechny změny použít příkaz lilo pro provedení vašich změn).

Pokud nahráváte modul pomocí Initial RAM disku (initrd), vložte správné parametry do souboru /etc/modules.conf a vygenerujte initrd znovu příkazem mk_initrd.

Nezapomeňte sdělit boot manageru změny v initrd. To provedete příkazem:

lilo

   Module Loading command options
   ------------------------------
    When loading the aic7xxx driver as a module, the exact same options are
    available to the user.  However, the syntax to specify the options changes
    slightly.  For insmod, you need to wrap the aic7xxx= argument in quotes
    and replace all ',' with '.'.  So, for example, a valid insmod line
    would be:
 
    insmod aic7xxx aic7xxx='verbose.irq_trigger:1.extended'