From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zdenek Kabelac Subject: Re: Extending DM w/ new target type Date: Fri, 02 Aug 2013 14:07:43 +0200 Message-ID: <51FBA10F.7070006@redhat.com> References: Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development Cc: John Strange List-Id: dm-devel.ids 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