On Wed, Oct 10, 2012 at 12:53 PM, Mark Post <[email protected]> wrote: > > >>> On 10/10/2012 at 11:35 AM, "Duerbusch, Tom" <[email protected]> > >>> wrote: > > > Just speaking to LVM... > > > > Striping the data across multiple volumes (which in modern dasd is already > > stripped in the Raid array), would give you the best performance. > > Especially if you can strip across multiple DS8000 (or other dasd > > subsystems). > > > > But you can also use LVM as a pool of DASD, with no striping involved. > > > > In case 1, if you need to expand the LVM pool, it is a hassle. It might > > mean backing up, reformatting and reloading the data. In any case, it > > involves a knowledgeable person and most likely, downtime. > > This is simply not true. Expanding a striped LV can be done dynamically with > no downtime. The only aspect that is different from a non-striped LV is that > you have to have enough free space on as many different PVs as the number of > stripes you have. That is, if you did an "lvcreate -i 2" then when you do an > lvextend/lvresize, you have to have free space available on 2 different PVs > in the pool. An "lvcreate -i 3" means you need free space on 3 PVs, etc. >
Not "really" true either. Even if you originally stripe with 2 or 3 or whatever, you can always "lvextend -i 1" to add another segment. That's because striping is done at the segment level and each segment can be configured independently. Mind you that you loose the performance benefit for that specific segment, but that can be remedied later when you have more time or can take the outage. Leland ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
