[DRBD-user] Question about sizes

Lars Ellenberg lars.ellenberg at linbit.com
Wed Jun 17 10:59:42 CEST 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Wed, Jun 17, 2009 at 09:38:07AM +0200, Rainer Sokoll wrote:
> Hi,
> my question is more LVM related, but I hope someone here will come up
> with an answer.
> I need to turn a physical machine into a virtualized one (Xen), I want
> to use drbd with LVM as storage backend. Therefore, I must tell lvcreate
> the exact size of the logical volume(s) that need to be created. Found
> http://www.drbd.org/users-guide/ch-internals.html#s-meta-data-size.
> But I do not know how lvcreate computes the sizes. The manpage says:
> -L, --size LogicalVolumeSize[kKmMgGtTpPeE]
>        Gives  the  size to allocate for the new logical volume.  A size
>        suffix of K for kilobytes, M for megabytes, G for gigabytes,  T
>        for terabytes, P for petabytes or E for exabytes is optional.
>        Default unit is megabytes.
> What is kilo/mega/giga here? 1024 or 1000?
> My goal is simply to dd the physical devices into logical volumes.
> Any idea?

man lvs says:
--units hsbkmgtHKMGT
  All  sizes are output in these units: (h)uman-readable, (s)ectors,
  (b)ytes, (k)ilobytes, (m)egabytes, (g)igabytes, (t)erabytes.
  Capitalise to use multiples of 1000 (S.I.) instead of 1024.  Can also
  specify custom  (u)nits  e.g.  --units 3M

I think that is also true for lvcreate, though there
it gets rounded UP to the next multiple of PE size anyways,
so for many values, g and G will result in the same number of PEs.

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
please don't Cc me, but send to list   --   I'm subscribed

More information about the drbd-user mailing list