[zfs-discuss] optimise away COW when rewriting the same data?

2010-01-24 Thread Kjetil Torgrim Homme
I was looking at the performance of using rsync to copy some large files which change only a little between each run (database files). I take a snapshot after every successful run of rsync, so when using rsync --inplace, only changed portions of the file will occupy new disk space.

Re: [zfs-discuss] optimise away COW when rewriting the same data?

2010-01-24 Thread David Magda
On Jan 24, 2010, at 10:26, Kjetil Torgrim Homme wrote: But it occured to me that this is a special case which could be beneficial in many cases -- if the filesystem uses secure checksums, it could check the existing block pointer and see if the replaced data matches. [...] Are there any

Re: [zfs-discuss] optimise away COW when rewriting the same data?

2010-01-24 Thread Kjetil Torgrim Homme
David Magda dma...@ee.ryerson.ca writes: On Jan 24, 2010, at 10:26, Kjetil Torgrim Homme wrote: But it occured to me that this is a special case which could be beneficial in many cases -- if the filesystem uses secure checksums, it could check the existing block pointer and see if the