On Wed, 16 Feb 2011, James Smallacombe wrote: > To: CentOS mailing list <centos at centos.org> > From: James Smallacombe <james at sicom.com> > Subject: Re: [CentOS] Software RAID Level 1, smartd and changing dev numbers > >> At Wed, 16 Feb 2011 12:00:27 -0500 (EST) CentOS mailing list >> <centos at centos.org> wrote: >>> >>> The problem is, the kernel seemingly randomly switches >>> between /dev/sdb and /dev/sdc for these devices. This >>> makes the process slower by requiring more manual input >>> where a script(s) could otherwise suffice. >> >> I'm assuming these are actually SATA disks with a >> controller that supports hot-swap. > > Correct. > >> What I think is happening is that the kernel retains some 'memory' of >> the pulled drive (say /dev/sdb) and when the fresh drive is installed, a >> new dev file is created (/dev/sdc). Eventually, /dev/sdb is forgotten >> by the time the next 'swap' and /dev/sdb is assigned to the next fresh >> disk. > > Interesting...one would think that this behavior would be consistent > across all servers then, but it isn't. Most accept the same dev, > /dev/sdb, but some assign /dev/sdc. Is there a way to just disable > /dev/sdc and force the kernel to use /dev/sdb every time? Can you identify any differences in the machines that don't re-assign the dev files, and the machines that do? Is this anything to do with UUID's on the drives/partitions? What parts do you have on the RAID drives? How are the drives setup as RAID - as bare drives/partitions, or via LVG? Keith ----------------------------------------------------------------- Websites: http://www.karsites.net http://www.php-debuggers.net http://www.raised-from-the-dead.org.uk All email addresses are challenge-response protected with TMDA [http://tmda.net] -----------------------------------------------------------------