Re: [PATCH] [RFC] Advanced TCA Disk Hotswap support in Linux Kernel [core 1/2]

From: Randy.Dunlap (rddunlap@osdl.org)
Date: Fri Oct 11 2002 - 10:27:59 EST


Hi,

On Thu, 10 Oct 2002, Steven Dake wrote:

| I am developing the Linux kernel support required to support Advanced
| TCA
| (PICMG 3.0) architecture. Advanced TCA is a technology where boards
| exist
| in a chassis and can either be processor nodes or storage nodes. All
| blades in the chassis are connected by FibreChannel and Ethernet. The
| blades can be hot added or hot removed while the Linux processor nodes
| are
| active, meaning that the SCSI subsystem must add devices on insertion
| requests and remove devices on ejection requests.
|
| The following is the first public patch that I am posting that adds
| support
| for SCSI and FibreChannel hotswap via a programmatic kernel interface,
| as well as userland access via ioctls.

Thanks for letting us know about it.
Does this project have a web page?

| The second patch is a FibreChannel driver that is modified to support
| SCSI hotswap.
|
| This mechanism is far superior to /proc/scsi/scsi because it:
| 1) provides true FibreChannel hotswap support (at this point qlogic FC
| HBAs)
| 2) is programmatic such that errors can be reported from kernel to user
| without looking is /var/log/.

so where does someone look for errors?

| 3) Provides superior response times vs opening a file and writing to
| proc.
| 4) Easier to control from kernel and user via C APIs vs using
| open/write.

Does this suggest adding yet another hotswap/hotplug mechanism
to Linux? It would be a good thing to unify them IMHO.

Does this hotswap mechanism require userspace software to activate it?
If so, is it available or being developed also?

-- 
~Randy
  "In general, avoiding problems is better than solving them."
  -- from "#ifdef Considered Harmful", Spencer & Collyer, USENIX 1992.

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