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On Wed, 2003-04-16 at 11:58, Cahill, Ben M wrote: > > -----Original Message----- > > From: Joe DiMartino [mailto:joe@osdl.org] > > Sent: Tuesday, April 15, 2003 6:48 PM > > To: Open GFS > > Subject: Re: [ogfs-dev]ogfs_jadd and EVMS FSIM > > > > I'm thinking still louder. :) > > > > > > Each CFS is made from 2 volumes. The first volume holds the > > actual file > > > system and the other volume holds the journal. The journal volume is > > > segregated into logical chunks which hold journaling information per > > > node. An example would be from offset 0 to offset x belongs > > > the journal of node 1, offset x+1 to 2x belongs to journal > > of node2, > > > and so on. This way you dont have to create a journal > > volume for each > > > additional node that adds to the cluster. And if space in > > the journal > > > runs out as node get added, the journal volume can be expanded. > > > > > > Does this sound reasonable? > > > Ram Pai > > > > Yes, it sounds reasonable to me. It should work with > > discreet journals > > or combined ones. The real question would be how to specify that a > > single volume could/should be split and make the divisions known to > > the FS. > > I've been avoiding this problem by assuming each external journal is on a > separate /dev/something. mkfs.ogfs queries the /dev/something with ioctl > BLKGETSIZE to find out its capacity. This is a seemingly "universal" way of > achieving this, with no dependency on a particular new API or scripting or > other protocol. > > It would not be a big stretch, though, to create several journals on a given > device. e.g., using a config file, if several journals are specified on the > same device (I've made this illegal in the first round of external journal > support, for now), then simply divide the BLKGETSIZE space equally among > all. What if you specify /dev/something with an offset and size (as was suggested). All entries in the config file can be checked for overlap. > # Number of journals > journals 2 > > # Journal definitions. > # Internal journals may specify a size in MBytes (not required) > # External journals must specify a journal device (required) > journal 0 ext /dev/sdb3 > journal 1 int 256 Also, Re: 'Number of journals' entry. I didn't mind seeing it there because I thought you were going to use it as the "current max" for near-future growth. Even though only journal 0 and 1 are defined in the config file, the 'journals' entry makes sure to size the pointers (external) and/or journal area (internal) appropriately. Maybe it can be optional - if not specified, total up the 'journal' entries (as suggested). -- Joe DiMartino <joe@osdl.org> ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ Opengfs-devel mailing list Opengfs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/opengfs-devel