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On Thursday 06 November 2003 04:00 pm, Arcot Arumugam wrote: > Hi > > Thanks for your responses. Couple of my thoughts. > > > Sounds like a good plan, except EVMS only supports raid-0 and linear, so > no > > kind of high availability. > > > > --Brian Jackson > > EVMS supports Linear, RAID-0, RAID-1 RAID-4/5 by the use of MD regions. > Please look at: > http://evms.sourceforge.net/users_guide/#id2888379 > Excerpt from the users guide below ... > <...> > There are four EVMS MD region plug-ins: > Linear, RAID-0, RAID-1, and RAID-4/5. > The RAID-4/5 region plug-in provides support for both RAID-4 and RAID-5 > arrays. > After an MD region manager is selected, the software provides a list of > acceptable objects. > The ordering of the MD array is implied by the order in which you pick > objects from the provided list. > The following are MD region configuration options: > (...) That is true, but not for cluster mode. The cluster mode (which is what you'll have to use with ogfs) only supports raid-0 and linear. > > > I believe you are right about being protected from a disk failure. > > > > But what if the computer managing your raid 1 volume dies. Obviously > > your whole ogfs cluster goes down. > > > > <...> > > Greg > > -- > > Greg Freemyer > > If I have EVMS loaded on C,D and ogfs runs on top of EVMS volume, > does not ogfs handle node failure? Yes your setup might work > but I am just trying the simplest approach possible. > > Also seems like I am not the only person who thought about this. > Saw this thread on EVMS list archives: > > From: > http://sourceforge.net/mailarchive/message.php?msg_id=5689532 > > >> First create a cluster container for the 2 iscsi drives. The > container > will > >> consume the 2 drives while producing 2 segment objects. Next, create > an > md > >> region, using the 2 segments, and mirror them to protect against disk > >> failure. This is assuming that the 2 iscsi targets are actually 2 > different > >> phys vols and that you mount them before running evms tools like > >> evms_activate or a configuration tool like evmsgui. > > >But EVMS doesn't handle RAID1 access synchronization for concurrent > >access as OpenGFS requires, surely? The metadata etc doesn't survive > >well if accessed from multiple nodes, and access to the raid chunks > >would also need to be synced and ordered. > > Thats what I get for only reading part of the post ... I agree. I was > assuming cluster private storage. When using cluster shared storage > (all > cluster file systems) you need to avoid features that employ such > metadata > ... this includes others like bbr as well. > > -Don > > I do not know what it means "EVMS doesn't handle RAID1 access > synchronization for > concurrent access as OpenGFS requires". EVMS folks think that this is the > only issue with this approach. Anyone can explain in english what the above > means. It means the same thing I told you... that it doesn't support raid-1/5 in cluster mode. > My guess is that metadata will be corrupted when accessed from multiple > nodes??? yep > What is cluster private storage anyway? > > Thanks again > > Arcot ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ Opengfs-users mailing list Opengfs-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/opengfs-users