this brings in a new dimension of analysis: On Wed, Jan 14, 2009 at 1:14 PM, Manish Katiyar <mkatiyar@xxxxxxxxx> wrote: > > Correct.... but that also raises few more questions. Sandeep , do you > have any pre-requisites about the sizing of disks for OHSM to work ?? > For example lets say I have 3 disks d1, d2 & d3 in descending order of > speed. Do all of them have to be of same size ? If they are then you > really don't need to worry much about space preallocation, because you i am confused....why "preallocation" in the first place? if the destination is guaranteed to have only the current kernel thread writing to it, then don't have to preallocate. and if destination is writable by many processes, then u need the source to be in readonly mode, to justify the preallocation. if source is NOT in readonly mode, then pointless to preallocate, as source files may grow bigger or smaller while backing up operation is going. and for the same reason, it is also impossible to compare disk size between d1 and d2 to determine storage space sufficiency. (ext2's terminology of "preallocation" is not the same as yours, as it is "preallocated" but not allocated until when needed, so space is still available for allocation by anyone). > know that if you had space in d1 to allocate an inode in first place, > you can replicate the same layout in d2. > > Problem comes when d2 is less than d1. Is it possible that you migrate > only some of the blocks to d2 and leave some in d1 if d2 runs out of > space ? > -- Regards, Peter Teoh -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
