Plan the allocation of storage on your everRun system to ensure that you have space for your virtual machines (VMs) and system management needs.
When you configure the everRun system, you create storage groups from the available logical disks. You allocate VM volumes and virtual CDs (VCDs) from these storage groups, the assignment of which can have a dramatic impact on system performance and your ability to fully utilize available storage capacity.
When allocating storage to your virtual machines (VMs), consider the following actions:
Observe storage maximums
The everRun software does not allow over-provisioning of storage. The aggregate required storage for all VMs and VCDs must be no more than the total available storage in the everRun system. The system prevents you from creating a volume for a VM from a storage group that does not have enough space.
Minimize stranded storage
Ensure that each PM has the same amount of storage capacity. If one PM has more storage than the other, only the minimum amount of space is available. For example, if one PM has 3 terabytes (TB) of storage and another PM has 2 TB of storage, the total amount of storage is 2 TB (least storage of either PM).
Observe 512B and 4K sector size restrictions
Stratus recommends using disks with the 4K sector size for better performance. When using 4K storage, ensure that your storage groups support the sector size of the VM volumes that you want to create or import:
Note that the boot volume for each VM must be 512B, regardless of the storage group's sector size. Only data volumes can use the 4K sector size. Ensure that your guest operating systems support 4K volumes before creating or attaching them.
Leave storage space for additional VCDs
Leave at least 5 GB of free space in a storage group to allow room to create VCDs for installing additional VMs and applications. (To conserve this storage space, consider deleting VCDs when you are finished using them.)
Leave storage space for VM snapshots
When you create each VM volume, you specify its volume size as well as the size of the larger volume container in which the volume and its snapshots are stored. To leave enough space for the snapshots that you plan to create, start by allocating a volume container that is at least two times the size of the volume that it contains; however, your needs may vary depending on VM snapshot activity. For more information about estimating the amount of storage needed in a volume container, see Sizing Volume Containers.
To conserve storage space in a volume container, you can remove older or obsolete snapshots as described in Removing a Snapshot. If necessary, you can also expand a volume container as described in Expanding a Volume Container on the everRun System.
Create separate boot and data volumes for each VM
Install the guest operating system and applications in the first (boot) volume, and create separate volumes for associated data. Separating the boot and data volumes helps to preserve the data and makes it easier to recover a VM if the boot volume crashes.
Create a boot volume with enough capacity for the guest operating system plus overhead
Observe the minimum space requirements of your guest operating system and consider allocating slightly more space to account for the formatted capacity of the volume and usage. For example, if you allocate 5 GB to the boot drive when creating the VM, the formatted capacity of the boot volume starts at approximately 4.8 GB before usage, and this might be insufficient to meet a 5 GB requirement.
Related Topic
Creating and Migrating Virtual Machines
Managing Virtual Machine Resources
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