[Users] Is this "dd" operation harmful?

[Dan Kenigsberg]

On Thu, Oct 11, 2012 at 03:44:25PM +0800, Shu Ming wrote:
> Hi,
> 
> I found some "dd" operations were launched contiguously in my vdsm.log.
> Is this harmful? How was this operation caused?

That's storage.storage_mailbox.SPM_MailMonitor, polling for lvextend
requests. dd is used, since in the old days, vdsm did not have
storage.fileUtils.DirectFile.

The behavior is expected, but I cannot say that it is harmless.
The mailbox should be high on
http://wiki.ovirt.org/wiki/Vdsm_TODO#refactoring
since forking so much is a waste, as well as using strings instead of
bytearrays. Making the module as a separate, testable entity, is important,
too.

> 
> From vdsm.log:
> 
> Dummy-51000::DEBUG::2012-10-11
> 15:38:57,243::__init__::1249::Storage.Misc.excCmd::(_log) 'dd
> if=/rhev/data-center/6f6d4801-7447-48ea-b516-627d83e7801e/mastersd/dom_md/inbox
> iflag=direct,fullblock count=1 bs=1024000' (cwd None)