[dm-devel] RAID1 Recovery

[Trantow, Wayne D]

Hello,
I am studying the dmraid-1.0.0.rc14, device-mapper_CVS Latest, and
Fedora 6 (2.6.18-1.2798) kernel dmraid code to understand the recovery
logic for a RAID1 set.  The usage scenario is where one disk in a mirror
dies, the user swaps in a clean disk and then invokes dmraid app to
copy/sync data to the new disk.

Within this context I have a couple questions:

- In kernel space, it looks like a recovery operation (RH_RECOVERING)
will take place if the mirror_target.resume (mirror_resume) handler is
called.  In user space, in dmraid/reconfig.c add_dev_to_set() func sets
up handler add_dev_to_raid1() which should start the recovery.  However,
as far as I can see, add_dev_to_set is not wired in to the rest of the
dmraid code (i.e., nothing calls it).  What was the intent here?  

- If you follow the call chain from add_dev_to_raid1 into device-mapper
it sets up a 'resume' call via an DM_DEV_RESUME ioctl dm_task, however,
in the device-mapper _cmd_data_v4 struct (in libdm-iface.c) the 'resume'
handler func is associated with the DM_DEV_SUSPEND ioctl not
DM_DEV_RESUME. Hence, even if you invoked add_dev_to_raid1, a direct
ioctl call to the kernel mirror_target.resume func is not possible.  Is
this a bug or intentional? Or am I not seeing it correctly?

Regards,
Skip Trantow
Manageability and Platform Software Division
Intel Corporation
Email: wayne.d.trantow at intel.com