[Users] Is this "dd" operation harmful?

[Shu Ming]

After reading the code, every mailbox should be 4096 byte size.
And the total mailbox size is host * 4096. Ony one host is here, so
the total mailbox size here is 4096. why should the 'dd' operation
read 1024000 byte which is 1000K byte much lager than 4096 here?

2012-10-11 18:54, 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)


-- 
---
舒明 Shu Ming
Open Virtualization Engineerning; CSTL, IBM Corp.
Tel: 86-10-82451626  Tieline: 9051626 E-mail: shuming at cn.ibm.com or shuming at linux.vnet.ibm.com
Address: 3/F Ring Building, ZhongGuanCun Software Park, Haidian District, Beijing 100193, PRC