On Wed, 16 Feb 2011, James Smallacombe wrote:
> To: CentOS mailing list <centos@xxxxxxxxxx>
> From: James Smallacombe <james@xxxxxxxxx>
> Subject: Re: Software RAID Level 1, smartd and changing dev numbers
>
>> At Wed, 16 Feb 2011 12:00:27 -0500 (EST) CentOS mailing list
>> <centos@xxxxxxxxxx> 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
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