I have to come back to this issue after a while cause it just hit me. I have a VMWare vSphere 4 test host. I have various machines in there to do tests for performance and other stuff. So a lot of IO/ benchmarks are done and a lot of data is created during this benchmarks.
The vSphere test machine is connected via FC to the storage box (Nexenta 3.0). Currently the data visible withing the VM's is ~ 10 GB (mostly OS only). ON the ESX host it is a lot more (no thin provisioning). On the Nexenta Box a lot more is used (~500G) because it has been used once. The test machine has not a lot of memory because I don't need it. So enabeling deduplication is not an option. Also benchmarks have shown that performance really sucks. So compression is an option yes, and I yield GREAT comression ratios (> 10x). However on the wire the full 500 GB are transfered. There is NO way to shring the volumes currently. I could compress the wire with gzip, however this would be VERY unefficient: (SOURCE) Disk Read (compressed) -> decrompression to memory -> comress on wire -> (TARGET) decompress on the other side -> compress for disk -> Write Disk (compressed) This means a lot of CPU is used. Not nice. Now If I think there would be "write all zero, clear the block again" in ZFS (which I suggest in this thread) I could do the following: Fill the disks within the VM's with all zero (dd if=/dev/zero of=/MYFILE bs=1M ...). This could effectibly write a lot for all-zero blocks to the comstar and zfs. ZFS could then free the blocks and I could then send the zvol to backup. This could mean 10 GB used in VM -> zvol size of ~10 GB -> 10 GB transfered. Doesn't this sound better ? Of course we could also wait for punch/trip support, tune the whole stack and wait until components in such a setup support trim ... but I believe this will take years. So the approach mentioned above sounds like a programmatic solution. Where can proposals like this be placed ? bugs.opensolaris.com ? -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
