[linux-lvm] Extend VG - Expand LUN vs New Disk

Jorge Fábregas jorge.fabregas at gmail.com
Mon Dec 21 16:13:35 UTC 2015

On 12/21/2015 08:50 AM, Bryn M. Reeves wrote:
> Expanding an existing LUN may involve resizing partitions - that is
> normally the step that makes this the more complicated route since
> depending on system configuration and use it may not be easy to resize
> the partition without downtime (the Linux kernel has for some time
> enforced restrictions on resizing in-use partitions - device-mapper
> devices and whole disk devices do not share this limitation).

We use whole disks all the time :)

> It's safe enough - it's just that the kernel generally won't let you
> do it while the existing partition is active and in use.

I'm glad to know that:  one more reason to use whole disks.  I know Red
Hat favors partitions for PVs (as mentioned in various docs) but I've
never been convinced by the arguments for it.

> Expanding an existing partition may be seen as the "cleaner" option,
> since it avoids creating additional PVs and associated labels and
> metadata areas, but unless you are working with very large numbers of
> devices it makes little difference to most operations.

Excellent point.

> Gluing lots of devices together is one of the main reasons for using a
> volume manager and for typical uses it adds no appreciable overhead
> or additional complexity.

Thanks Bryn for your wonderful feedback.  I appreciate it!

All the best,

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