Long ago, Nostradamus foresaw that on 01/24/2013 01:08 PM, Alasdair G Kergon would write: > If you've got the capacity to test, create one that's quite a bit > larger and see how much space it actually uses up when full, then use > that size in future. There's a header, and then the blocks are written > sequentially with an index block inserted ahead of each group of > data blocks. > > Or try out thin LVs available in recent LVM releases/kernels for > an alternative 'sparse' approach. He doesn't actually want sparse, he wants "instant zero" via copy on write. This is useful for virtual machines by preventing information leaks between customers. Currently, you can create a "template" LV, and have a snapshot for each VM. Since you (almost) never write to the template, you don't run into the performance issue. He proposed a new type of LV that is a normal LV plus a small bitmap (1 bit per chunk) that tracks which chunks have been written to. When a chunk is written to, the remainder of that chunk is set to zero. Reads from unwritten chunks always return zeroes. _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
