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.robin...@motec.com.au> 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@centos.org > http://lists.centos.org/mailman/listinfo/centos -- Lec _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
