Problem in hotplug (BFS - AS4)

Problem in hotplug (BFS - AS4)

[Srikanth Venkataraman]

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Hi All,

We have a Boot from SCSI setup and we are facing some problem. Problem
description is given below

System configuration: -
OS: AS4 UPDATE 1  [2.6.9-11.ELsmp]
Memory:  1 GB
QLA2310 Driver Info: Driver version 8.00.00b21-k, Firmware version 3.03.02
IPX
Setup: Boot From SCSI

Scenario 1:
Devices: 1024 SCSI devices
Utility gives the problem: /sbin/hotplug
Observation: udev process hangs and after some time kernel panic occurs.

Scenario 2:
Devices: 512
Utility:/sbin/hotplug
Observation: Boot from San success.

Scenario 3:
Devices: 1024
Utility: /sbin/udevsend
Observation: Boot from San success


Can any one answer the following queries: -

    1. Are 512, the maximum number of devices that can be supported in Boot
from San in AS4 with hotplug agent?
    2. If not what is the hardware requirement for more devices to be
supported or how it can be rectified?
    3. Can we use utility /sbin/udevsend instead of /sbin/hotplug. Will it
impact any other process or devices?
    4. Is /sbin/udevsend and /sbin/hotplug similar in functionality.


Thanks & Regards,
Srikanth Venkataraman.



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Re: Problem in hotplug (BFS - AS4)

[Kay Sievers]

On Sat, Feb 18, 2006 at 03:19:47PM +0530, Srikanth Venkataraman wrote:
> Hi All,
> 
> We have a Boot from SCSI setup and we are facing some problem. Problem
> description is given below
> 
> System configuration: -
> OS: AS4 UPDATE 1  [2.6.9-11.ELsmp]
> Memory:  1 GB
> QLA2310 Driver Info: Driver version 8.00.00b21-k, Firmware version 3.03.02
> IPX
> Setup: Boot From SCSI
> 
> Scenario 1:
> Devices: 1024 SCSI devices
> Utility gives the problem: /sbin/hotplug
> Observation: udev process hangs and after some time kernel panic occurs.
> 
> Scenario 2:
> Devices: 512
> Utility:/sbin/hotplug
> Observation: Boot from San success.
> 
> Scenario 3:
> Devices: 1024
> Utility: /sbin/udevsend
> Observation: Boot from San success
> 
> 
> Can any one answer the following queries: -
> 
>     1. Are 512, the maximum number of devices that can be supported in Boot
> from San in AS4 with hotplug agent?

Depends on your box and setup. /sbin/hotplug never worked in such setups
and is known to cause OOM when too many devices are created at the same
time. Just get rid of it.

>     2. If not what is the hardware requirement for more devices to be
> supported or how it can be rectified?

Use a recent udevd, which connects directly to the kernel uevent socket.

>     3. Can we use utility /sbin/udevsend instead of /sbin/hotplug. Will it
> impact any other process or devices?

udevsend was a workaround during the replacement of /sbin/hotplug by a
generic device event daemon. udevsend is no longer supported and already
disabled in recent udev versions, it will be completely removed some
day.

>     4. Is /sbin/udevsend and /sbin/hotplug similar in functionality.

If you have only a few devices without any event order requirement,
basically yes. udevsend just sends all events to the udevd daemon which
forks the events. The daemon takes care of the event reordering and
that your box does not get killed by too many running event processes.
But as said above, just use the udev daemon and disable the kernel event
process forking completely, cause it simply can't work reliably in your
setup.

Kay


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