[Users] Is this "dd" operation harmful?

[Rami Vaknin]

On 10/11/2012 09:44 AM, Shu Ming wrote:
> Hi,
>
> I found some "dd" operations were launched contiguously in my vdsm.log.
> Is this harmful? How was this operation caused?

dd is the way vdsm reads and writes data in its metadata luns of a
storage domain.

Each storage domain (except for nfs-based storage domains) has several
special luns for managing the storage domain operations, one of them is
the inbox which is used for communication between hosts about storage
domains write operations that should executed by the SPM host etc.

The only thing I'm not happy with is the usage of 'dd' instead of '/bin/dd'.

>
> 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)
> Dummy-51000::DEBUG::2012-10-11
> 15:38:57,305::__init__::1249::Storage.Misc.excCmd::(_log) SUCCESS: <err>
> = '1+0 records in\n1+0 records out\n1024000 bytes (1.0 MB) copied,
> 0.0388821 s, 26.3 MB/s\n'; <rc> = 0
> Dummy-51000::DEBUG::2012-10-11
> 15:38:59,313::__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)
> Dummy-51000::DEBUG::2012-10-11
> 15:38:59,375::__init__::1249::Storage.Misc.excCmd::(_log) SUCCESS: <err>
> = '1+0 records in\n1+0 records out\n1024000 bytes (1.0 MB) copied,
> 0.0398412 s, 25.7 MB/s\n'; <rc> = 0
> Dummy-51000::DEBUG::2012-10-11
> 15:39:01,383::__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)
> Dummy-51000::DEBUG::2012-10-11
> 15:39:01,445::__init__::1249::Storage.Misc.excCmd::(_log) SUCCESS: <err>
> = '1+0 records in\n1+0 records out\n1024000 bytes (1.0 MB) copied,
> 0.0393934 s, 26.0 MB/s\n'; <rc> = 0
> Dummy-51000::DEBUG::2012-10-11
> 15:39:03,453::__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)
> Dummy-51000::DEBUG::2012-10-11
> 15:39:03,515::__init__::1249::Storage.Misc.excCmd::(_log) SUCCESS: <err>
> = '1+0 records in\n1+0 records out\n1024000 bytes (1.0 MB) copied,
> 0.0391104 s, 26.2 MB/s\n'; <rc> = 0
>


-- 

Thanks,

Rami Vaknin, QE @ Red Hat, TLV, IL.