From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phil Turmel Subject: Re: [PATCH] md: register new md sysfs file 'uuid' read-only Date: Mon, 08 Oct 2012 13:50:53 -0400 Message-ID: <5073127D.7070500@turmel.org> References: <1349185330-9024-1-git-send-email-sebastian.riemer@profitbricks.com> <20121003083031.51093f0c@notabene.brown> <50730010.5090605@profitbricks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50730010.5090605@profitbricks.com> Sender: linux-raid-owner@vger.kernel.org To: Sebastian Riemer Cc: NeilBrown , linux-raid List-Id: linux-raid.ids On 10/08/2012 12:32 PM, Sebastian Riemer wrote:> Hi Neil, > > I must have overseen your answer. We want to use as less mdadm as > possible - especially for simple checking stuff. The kernel knows best. > "mdadm -D" reads the data from disk. This means additional disk access. > It is also possible that this command triggers superblock updates. > Simple checking stuff shouldn't have to use disk access. > > We are planning to use MD RAID a little bit different with e.g. 100 MD > arrays. Searching for a particular UUID in this bunch of MD devices can > be difficult without this patch. This is how the kernel represents > UUIDs. Conversion can be done in user space. > > If you like it better in the xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx format, > I can resend the patch in that format. If you are aiming for consistency, the dm driver(s) have already established a no-punctuation format for the UUID itself (punctuation separates UUID type from the UUID) within sysfs. Regards, Phil