alex davila wrote:Non-sparse allocation has nothing to do with thin provisioning. The best possible disk performance into a VM is a physical LUN directly mapped into a guest. This would be either thin or thick provisioned on the SAN itself. If you must use virtual disk images, a non-sparse disk image would have consistent performance, as there is no requirement to grow the image as more data is added. However, once a sparse disk image is fully sized, it will perform exactly the same way as a non-sparse disk image. Sparse disk images never reduce in size, only grow.
My question here is: To create a VM with non sparse allocation (that works better in san writing), we have to have storage with NO thin provisioning? or is independent one from another?
Dylan G. wrote:No, there isn't.
There 2 level of thin provisioning here.
1] SAN storage level - most SAN or Unified Storage able to do thin provision on volume. On storage, you will see the actual capacity used compare to total capacity crafted. But on the host, it would know it is thin or thick, as a disk is a disk, which will be used as repository or direct mapped disk.This is thick/thin provisioning on the SAN.
2] OVM level - you create virtual disk on the repository, opt to thick or thin.This is sparse/non-sparse file creation. Has nothing to do with thick/thin provisioning from the SAN.
alex davila wrote:This implies that your repo is possibly sitting on a thinly provisioned LUN -- i.e. the files are either sparse/non-sparse, but the LUN itself is thinly provisioned, so both write operations require the LUN to grow on the SAN. Once the LUN has grown to incorporate the new data, the data transfer rates are faster.
First machine was sparse & second non sparse
The space is reserverd and the write to Virtual Disks is much better
alex davila wrote:Because you are probably putting both the sparse/non-sparse files on a thinly provisioned SAN LUN: thus, for both instances, the SAN itself has to expand the LUN to fit the new data, just like the sparse file has to do. Try and ask your SAN administrators for a non-thinly provisioned LUN, if your SAN can provide such a thing.
Any Ideas why