We have a one lun for each vm. I cannot say witch is better but as some people say it is an administrative nightmare i cannot agree, You must have very few VMs. We have a bit over 200 VMs i...
See more...
We have a one lun for each vm. I cannot say witch is better but as some people say it is an administrative nightmare i cannot agree, You must have very few VMs. We have a bit over 200 VMs in our infrastructure, among 8 physical servers, on our EVA 5000. The EVA 5000 has 2 controllers, and every server has 2 HBAs. If we had one LUN per VM, we would have 800 paths to the LUNs (every LUN would be visible 4 times: 1 per HBA and 1 per EVA controller). That is well beyond the 128 hard limit on ESX. We have some 256GB LUNs and some 512GB LUNs, and distribute the VMs among them. Lighter machines go to bigger LUNs (more machines per LUN). We don't create and delete LUNs all the time; we set them some time ago, and then added some, but it stays relatively unchanged. Avoid change whenever possible: I never heard of "spontaneous" problems arising in stable machines; however, upgrades and changes tend to be troublesome... Or, as they say: if it works, don't "fix" it. We also give every machine its own .vmdk just for paging, and have LUNs specifically for holding .vmdk with pagefiles. We tend to give machines a bit more memory than strictly needed, so pagefiles are there to give machine owners that "warm fuzzy feeling", as they're seldom used (if ever). Indeed, we're considering putting these .vmdk files in some lower grade storage, and keep the real stuff in the EVA. Another reason why we have dedicated .vmdk for pagefiles is because of backups: pagefiles tend to be placed on the C: drive, but we have a policy of keeping C: as small as possible, so we can keep restore times low. Pagefiles are not backed up, so they need not to be restored. Having different LUNs for different kinds of volumes (one LUN for system drives, another for pagefiles, etc.) also allows optimizations on the storage level - like using vraid1 for databases and vraid5 for system drives and pagefiles. Paulo