[dm-devel] Extending DM w/ new target type
Zdenek Kabelac
zkabelac at redhat.com
Fri Aug 2 12:07:43 UTC 2013
Dne 1.8.2013 19:04, John Strange napsal(a):
> two questions:
>
> 1. I'd like to use DM with a new target type. I'm porting our virtualized
> storage solution from Windows. I've been able to register my target and get
> callbacks working, but in looking at the dm-raid code, I'm concerned with how
> tightly coupled it is with the routines in md.c (multiple devices
> implementation). Is there an expectation that a DM target use the md_xxxx
> routines?
>
> 2. I used dmsetup to create a mapping for a device that my target controls.
> Is there a way to make the underlying device (e.g. /dev/sdb) not visible to
> the system? I'm paranoid about external accesses to a LUN that I'm using.
In lvm2 it's solved in a way - that we use special flags for udev to avoid
some scanning/watchrules - however all device are always available through
/dev/mapper but user visible devices are accessible via /dev/vg/lv name
which is the only suggested and supported way to use LVs.
Obviously we often get reports where users are directly playing with
/dev/dm-XXX devices or /dev/mapper/vg-lv in their scripts and configs...
But you can't hide existing devices in system from userland visibility.
Zdenek
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