sd devices on FC14 AMI not valid?

Raphaƫl De GIUSTI raphael.degiusti at guardis.com
Thu Feb 10 08:28:43 UTC 2011


As far as I know, the device name could be anything, as long as the device
is associated with the right minor and major number. The symlink is
not necessarily ugly, but the patch solution is better imo.

On Thu, Feb 10, 2011 at 3:39 AM, David HM Spector <spector at zeitgeist.com>wrote:

> Iiinteresting.   Seems like the rightscale AWS gem (which I am using in my
> scripts to actually do the attach of the EBS volume) doesn't like xvd device
> entries.. however symlinking the sd device name to the real xen one allows
> it to work (ugly, yes... but it works)...   will have to look into that and
> submit a patch if its really broken.
>
> thanks much for your help - it got me where I needed to be
>
> cheers,
>    David
>
> On Feb 9, 2011, at 6:28 PM, Brian LaMere wrote:
>
> replace "sd" with "xvd" and you'll be set.  It's not a "*s*csi *d*isk" but
> instead a "*x*en *v*irtual (block) *d*evice"
>
> On older AKIs, sometimes one would see drives presented to the OS as
> /dev/sd* still, but it seems like since pvgrub this is no longer the case.
>  It's more "honest" this way regardless; the kernel is seeing it (or at
> least, presenting it) more accurately for what it is.  It never should have
> listed those drives as /dev/sd*
>
> So...point is...it's not supposed to be /dev/sd* - just like it wasn't
> /dev/sd* when you used old IDE drives (those were /dev/hd*).  Almost all
> kernels have built-in support for IDE and SCSI, but not for Xen; that's
> loaded as a module, instead.  If you do an "lsmod" you should see a loaded
> module named xen_blkfront - note also that it has a "used by" value that is
> the same as the number of (valid...) /dev/xvd* block devices.
>
> See http://lxr.free-electrons.com/source/drivers/block/xen-blkfront.c for
> info about that module...
>
> Does that answer the question?  Disregard what Amazon says you should see
> the device reporting as - it should be xvd*, not sd*.  It's not using the
> scsi driver.
>
> Brian
>
> On Wed, Feb 9, 2011 at 5:49 PM, David HM Spector <spector at zeitgeist.com>wrote:
>
>> I am trying to get an attached EBS volume to mount on a customized (ots of
>> php and rails packages) version of the FC14 AMI.
>> It seems the sd devices aren't made by default; but even once they're
>> made, mount refuses to mount the volume
>> saying " /dev/sdf is not a valid block device"   Its a an ext3 filesystem
>> so nothing novel there.
>>
>> Everything works fine on my older instances with the same scripts; I can
>> get he EBS volume to attach to the instance (I have
>> some custom ruby scripts that work at startup to attach vol ids passed as
>> user data) and the perms/maj/min device numbers
>> look OK too (as one would expect from MAKEDEV).
>>
>>  Anything obvious I am missing?
>>
>>
>> tnx,
>>   David
>>
>> ----------------------------------------------------------------------------------------------
>>                                           David HM Spector
>> spector at zeitgeist dot com
>> http://www.zeitgeist.com
>>                                                     ~ ~ ~
>> "New and stirring things are belittled because if they are not belittled,
>> the
>> humiliating question arises, 'Why then are you not taking part in them?'"
>>
>>             --H. G. Wells
>>
>>
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> ----------------------------------------------------------------------------------------------
>
>                                           David HM Spector
>
> spector at zeitgeist dot com
> http://www.zeitgeist.com
>
>                                                     ~ ~ ~
>
> "New and stirring things are belittled because if they are not belittled,
> the
>
> humiliating question arises, 'Why then are you not taking part in them?'"
>
>
>             --H. G. Wells
>
>
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