On 04/03/2014 06:25 AM, Tom Robinson wrote:
> On 02/04/14 20:17, Alexandru Chiscan wrote:
>> On 04/02/2014 01:00 AM, Tom Robinson wrote:
>>> On 01/04/14 17:49, Alexandru Chiscan wrote:
>>>> On 04/01/2014 06:27 AM, Keith Keller wrote:
>>>>> On 2014-04-01, Tom Robinson <tom.robinson@xxxxxxxxxxxx> wrote:
>>>>>> Now, I understand that Red Hat (and therefore CentOS) backport many upstr=
>>>>>> eam features into the stock
>>>>>> kernel so how can I be sure that kernel 2.6.32-431.11.2.el6 has write bar=
>>>>>> rier support?
>> from the kernel changelog
>> (https://access.redhat.com/knowledge/sources/source_rpms/kernel-2.6.32-431.11.2.el6/changelog)
>> the barrier support for filesystems, lvm (dm) and md is active from 2.6.32-82-el6
>>
> Thanks Alexandru,
>
> I did look at the changelog but, for my untrained eye, I saw no specific reference to LVM there (and
> indeed still don't in your list above). Are you saying that because dm is patched, LVM is now
> implementing barriers correctly?
As what I know the LVM system is implemented on top of dm (device mapper) (see
http://en.wikipedia.org/wiki/Logical_Volume_Manager_%28Linux%29) so it should handle the
barrier requests if dm does it.
<quote>
In the 2.6-series of the Linux Kernel, the *LVM is implemented in terms of the **device
mapper <http://en.wikipedia.org/wiki/Device_mapper>*, a simple block-level scheme for
creating virtual block devices and mapping their contents onto other block devices. This
minimizes the amount of relatively hard-to-debug kernel code needed to implement the LVM.
It also allows its I/O redirection services to be shared with other volume managers (such
as EVMS <http://en.wikipedia.org/wiki/Enterprise_Volume_Management_System>). *Any
LVM-specific code is pushed out into its user-space tools, which merely manipulate these
mappings and reconstruct their state from on-disk metadata upon each invocation.*
</quote>
Regards,
Lec
>
> Kind regards,
> Tom
>
>
>
> _______________________________________________
> CentOS mailing list
> CentOS@xxxxxxxxxx
> http://lists.centos.org/mailman/listinfo/centos
--
Lec
_______________________________________________
CentOS mailing list
CentOS@xxxxxxxxxx
http://lists.centos.org/mailman/listinfo/centos
