On Sun, Oct 08, 2006 at 07:40:12PM +0200, Bodo Thiesen wrote: > We are talking about commiting transactions or not committing > transactions. Assume we have a big file, and ind block I1, dind > block D1 and tind block T must be changed to be self-consistent. Ok, > no problem, we store the original contents of this three blocks in > memory, and then update (i.e. zero out) some parts. In the next > transaction, we need to change I2, D2 and T. If I1 != I2, we restore > I1 in this transaction - it's no longer needed, remember the old > content of I2 and log the changes for I2 in the journal. Same "In the next transaction" --- that's exactly the problem, as I said, in my earlier comment: You could if you forced transaction boundaries between every single indirect block, but that would seriously degrade ext3's unlink performance, and slow down any other filesystem activity that might be happenning at the same time. The way ext3 works is that we batch multiple operations into a single transaction. This is because commiting transactions is expensive, so we amortize the cost over potentially a large number of filesystem operations that might be happening very close together. So your "trick" would require force a single unlink system call to require into multiple ext3 transactions, each which would have to be written to the disk, and which would have to stall until all journal blocks have been written to the disk before the journal commit block is written. The resulting performance degradation would be disastrous. - Ted _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
