From mboxrd@z Thu Jan 1 00:00:00 1970 From: malahal@us.ibm.com Date: Fri, 9 Oct 2009 10:56:47 -0700 Subject: Re: [PATCH 0 of 10] LVM: Mirrored log support In-Reply-To: <1255036474.12319.16.camel@hydrogen.msp.redhat.com> References: <1255036474.12319.16.camel@hydrogen.msp.redhat.com> Message-ID: <20091009175647.GA7737@us.ibm.com> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Jonathan Brassow [jbrassow at redhat.com] wrote: > These patches are a replacement to the proposed patches - a fresh start. > They address a couple problems that I saw with the old patches: 1) > Allocation policies are respected and behave the same as today for other > log types. > 2) The on-disk layout of the previous version - when given only two > disks to allocate from - would put the log on the front of one device > and the back of another. This virtually ensures a performance hit. > These patches put the logs in the same place WRT the images. > 3) The new patches reduce parameter bloat. I think the previous patches > required the extra parameters because they were using functions deep in > the code that were from higher levels... adding parameters and > "spaghettifying" the code. Thank you, Jonathan. I tested creating mirrored volumes with the new patchset and was able to activate/deactivate with the old patchset and vice-versa. I was able to create mirrored volumes with new patchset and was able to activate/deactivate with the virgin 2.02.53 LVM code. > These patches should be considered a starting point. While 'lvcreate' > works, 'lvconvert' does not handle all transitions. In fact, > 'lvconvert' will only handle 'core' -> 'disk/redundant' and > 'disk/redundant' -> 'core'. It will not handle 'disk' <-> 'redundant'. I haven't tried these, will try next. Initially, I thought anyone wishing to go from 'disk' to 'redundant' can go to 'disk -> core' and then 'core -> redundant'. The only problem is they may lose the 'sync' status and the second conversion may sync the mirror data. We can either choose to support 'disk <-> redundant' OR supply '--nosync' option to lvconvert. What do you think? Thank you again for the patchset. --Malahal.