While disk array vendors are working to optimize virtual machine (VM) data storage management, one administrator using DataCore Software Corp.'s SANmelody to manage high availability for VMware Inc. virtual servers said there's only so much those vendors can do. Scott La Vertu, network services manager at the Public Transport Authority of Western Australia, said what would help him most is for VMware to add support for LUNs larger than 2 TB within vSphere.
VMware can technically support larger volumes if the virtual hosts are attached to a NAS system via NFS, but La Vertu said the IP video surveillance application he's hosting on VMware servers is designed for a block-based storage system.
"VMware has a storage limit of 2 TB per LUN due to 32-bit addressing with a 512-byte block size," La Vertu wrote to SearchStorage.com in an email. La Vertu said he's asked VMware for 48- or 64-bit addressing because vSphere 4 uses a 64-bit kernel. "We want to use a block-level device to reduce the latency and also because all of [our closed circuit TV vendor's] research into their application efficiency and scaling has been with block-level devices," he said.
Other issues like I/O contention and SCSI reservations have cropped up as storage admins in large environments grapple with growing VMware deployments.