[Linux-PowerEdge] Extremely poor performance with LVM vs. RAW disc

James A. Peltier jpeltier at sfu.ca
Tue Nov 6 10:40:48 CST 2012


----- Original Message -----
| > ----- Original Message -----
| > 
| > | Once upon a time, James A. Peltier <jpeltier at sfu.ca> said:
| > | > Slicing and dicing the disk using partitions is completely
| > | > unnecessary, adds additional overhead and complexity and is far
| > | > less flexible.
| > | 
| > | Please cite the "additional overhead" of partitions (hint: there
| > | is
| > | none).
| > | 
| > Oh, and if you want to resize a virtual disk that uses LVM,
| > you need to delete the partition and recreate it.  Yup, that's one
| > too.
| 
| What do you mean by that?
| --
| Pavel Mateja


If you have a virtual disk that uses partitions then the partitions are fixed to the size of the volume as it was originally created.  It will not see the additional disk space on the volume unless you delete the partition and recreate it, thereby including the new space.  This is simply not necessary with whole disk LVM.

However, I will concede one thing *against* whole disk LVM and that is that whole disk volumes don't work so well in multi-boot environments or during new kickstarts.  This is because it looks to the OS that the disk has *NOT* been partitioned and so if care is not take you *COULD* wipe out the PV properties, however, we're all good admins of course so that never happens.  At least so far it hasn't happened to me.  That said, I still believe whole disk logical volumes remove many constraints that partitions put on you for storage management.  The whole point is to use logical volume manager to slice and dice the disk, not partitions + volume manager to slice and dice them.

-- 
James A. Peltier
Manager, IT Services - Research Computing Group
Simon Fraser University - Burnaby Campus
Phone   : 778-782-6573
Fax     : 778-782-3045
E-Mail  : jpeltier at sfu.ca
Website : http://www.sfu.ca/itservices
          http://blogs.sfu.ca/people/jpeltier

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