[dm-devel] noob usage question

[John Strange]

Yes, I think I do want to create partitions.  My expectation is to create a
mapping based on one or more raw physical device (luns).  There are a
number features I would like implement behind my mapping target driver.  My
understanding is that I can treat the mapping (the target device) as if it
were a raw disk and that I can format it as appropriate for whatever
workload will use it.

For instance... I need to present a device (it would appear to the OS as a
raw block device) composed of ranges of blocks from different devices -
spinning media, ssd, PCIe flash, etc.  My target driver can guarantee a QOS
(throughput, latency, combo) and it will service read requests across the
range of physical media comprising the target.

This target device would appear to the OS as a block device.  The workload
that uses the device might require a filesystem on it, so I need to mount a
FS.

That's what I'm aiming for.  I ran into problems trying to format my target
device so I created a linear mapping and it behaved the same way... could
not put a partition on it or format it.

-john


On Fri, Aug 9, 2013 at 4:22 PM, Brassow Jonathan <jbrassow at redhat.com>wrote:

>
> On Aug 9, 2013, at 4:01 PM, John Strange wrote:
>
> > When I create a linear target, I can't create partitions or format the
> mapped drive.  I get an invalid parameter argument for an ioctl.  I'm
> obviously doing something stupid.  What do I need to do to create
> partitions, format, mount a dm-n?
>
> You don't want to create partitions, do you?
>
> Just create an mapping and use it.  If you need another, create another.
>  Need to remove one, just remove it.
>
> Also, I'm assuming you want to use device-mapper.  If you want persistent
> devices (ones that stick around after a reboot), you may wish to use LVM.
>
>  brassow
>
>
>
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