Planning Your Storage Strategy

Use this overview and descriptions of the different types of storage disks used in the V5000 system to plan how and where your system will store and use your data.

Note: Before planning your storage usage and capacity configuration, see System Overview to learn how the system works and see Community and Licensed Subscription Edition definitions, VM configurations and more.

After this topic, continue to installation.

As discussed in DXi Installation, the hypervisor you use to install will determine the installation process to use for your V5000. Both of the following installation methods are illustrated in the topic:

V5000 Storage, Disk Types, and Planning Capacities

Your V5000 works with any type of disk you provide, but for optimal performance Quantum recommends your using the four types of disks described in Storage Disk Types.

VM disk storage can be created (provisioned) as thin or thick, as defined in Disk Provisioning Types.

In virtual storage, it is useful to consider thin provisioning vs. thick provisioning for your storage disks to optimize performance.

Thin provisioning means a minimum amount of disk space is allocated and expands as the VM requires it, up to a defined maximum size. Although thin provisioning can save disk space, it should generally not be used for a DXi in a production environment.

This method is attractive because it is quickly configured and only uses as much physical disk space as needed, avoiding wasted space and saving on upfront storage costs. The space can grow over time, though, and if your disk runs out of space, the DXi will fail.

For example, you can allocate 1 TB or less of actual disk space for a VM disk that has a maximum allocation of 10 TB. So this disk initially only uses 1 TB, but could grow to 10 TB. If the disk space isn't available, the DXi VM will fail.

Thick provisioning simply means that 10 TB of physical disk are allocated for a 10 TB VM drive. So there is no problem with the VM drive growing beyond what is available. And performance is generally fastest with a thick provisioned disk.

Thick provisioning is the safest option and avoids potential failures. Quantum strongly recommends use of thick-provisioned disks if the DXi is to hold production data.

Since a V5000 is holding your backups, the underlying physical storage should be reliable. RAID 6 is recommended. The hypervisor allows you to map the disks as you like, including for example using iSCSI, raw disks, FC attached storage, etc.

The DXi V5000 uses four different types of virtual disks. Using different virtual disk types allows you to assign the various types of data (operating system, bulk disk, metadata, and bulk storage) to different, specifically assigned virtual disks.

For example, virtual disks on fast media like SSDs or NVMe if available are best used for metadata, which requires using relatively small, high-frequency I/O (input/output) activity. Metadata capacity is small compared to bulk data. Bulk data may be 256 TB while metadata capacity is approximately 1% of the bulk capacity.

Quantum strongly recommends that you use separate disks or for the different data types. While it is possible to configure only a boot disk and a single SCSI-type disk for all metadata and bulk storage data, the installer will display a warning. This configuration will work for a 5 TB Community Edition DXi, but it will not be expandable and cannot be licensed. Configuring your system to use a boot disk plus at least 3 SCSI disks creates a licensable VM.

INSTALLATION TIP

It is possible to confuse the VM installer where it may use one of the intended bulk, SN-meta, or BP-meta disks as the boot disk! To prevent that, create a VM with 2 SCSI controllers, one to be used with the boot disk, the second with your SCSI disks.

The boot disk is a single, fixed-size disk of 100 GB or more, used for:

  • Operating System (OS)

  • Kernel

  • Logs

  • Temporary storage for software upgrade files

  • Temporary storage for core dumps

  • Configuration data

BOOT DISK NOTES:

  • Boot disk space cannot be expanded after the VM is created.

  • If installing from OVA, then the disk will be 100 GB. If installing from ISO, then you need to choose 100 GB or more.

  • 100 GB is the minimum size and cannot be increased after installation is complete. If enough space is available future upgrades may require more space, so 120 - 150 GB is recommended.

One or more Bulk disks are configured to hold user data, including your backup files. These disks experience relatively large random I/O activity.

  • SN-meta - 1 or more disks that hold the filesystem metadata.

  • BP-meta - 1 or more disks that hold the system's blockpool metadata.

    Note: Although not required, Quantum recommends using SSDs or NVMe fast-backed storage for metadata, which uses high-frequency and small I/O activity.

Note: SCSI (Small Computer System Interface), noted below, refers to the definition of the virtual disk in the hypervisor. The physical disk is managed by the hypervisor and can be of any hypervisor-supported type.

Boot Disk + SCSI Disks Warnings/Messages Displayed During Installation
Boot Disk + 1 SCSI Disk This is the simplest install configuration, using one 100 GB boot disk and one 100 GB - 5 TB bulk storage disk. But for a Community Edition install only, because this configuration cannot be changed to a Quantum-supported, Licensed edition.
Boot Disk + 3 SCSI Disks

This configuration:

  • is the recommended configuration for an ISO installation.

  • is automatically created by the OVA image.

  • can be licensed and expanded at will.
Boot Disk + 4 or More SCSI Disks

This works in the same way as the Boot + 3 SCSI disk installation, except that extra disks will be used for bulk storage. The V5000 initial setup process will display a VM desktop dialog, requesting storage configuration information.

The disks described here are defined in Storage Disk Types.

The V5000 Configurations and Stream Counts tables in System Overview show that SN-meta data can vary in size from 5 GB (minimum for the Community Edition) to 256 GB, which is a small size range, compared to growing your VM to hundreds of TBs. You may determine that it is more efficient to create a VM that will hold 256 GB of SN-meta data to avoid later expansion.

Planning capacity for your BP-meta disk(s) and your SN-meta disk(s) are similar. BP-meta storage scales from 52 GB to 2360 GB. Setting your BP-meta disk capacity as large as you can afford will reduce the time and effort needed for a subsequent or multi-step storage expansion.

Review your hypervisor documentation as you plan your storage capacities to determine the largest single-disk limits, virtual SCSI controllers, etc. Some hypervisors are unable to create a single 256 TB disk. Your hypervisor may also limit the number of disks you can attach to a single (virtual) SCSI controller. You can always add more than 1 virtual SCSI controller in the DXi. There are no limits on the DXi-supported number of disks or controllers.

Note: Bulk, SN-meta and BP-meta disks must show as SCSI devices when configuring your DXi.

Recommendations and Best Practices

The following recommendations and best practices are provided to assist your configuration planning.

Quantum recommends the following in planning your V5000 system storage strategy:

  • Use the free Community Edition installation as-is with no expiration or as a proof of concept before planning a larger Licensed Edition installation. When moving to a larger system you may readjust your storage capacity and disk allocation. See Community and Licensed Editions in System Overview.

  • To try a quick setup and demo, install the minimum storage configuration. If you know before installing that you will expand your system beyond the minimum capacity, do some advance planning to reduce or avoid near-term, multi-step expansions.

  • Hypervisors support VMs with multiple low-capacity disks, but for easier system management Quantum recommends creating disks in the VM with the largest size possible, based on your disk structure and system budget.

  • Looking at the V5000 Configurations and Stream Counts table in System Overview and Requirements, you can see that SN-meta Disk(s) can vary in size from 5 GB to 256 GB, which is relatively low compared to growing your VM to hundreds of TB. It may be more efficient to create a VM with 256 G of SN-meta, and thus avoid expanding SN-meta later.

  • You can install a Community Edition with any size SN-meta disk, greater than or equal to 5 GB.

  • BP-meta disk storage scales from 52 GB to 2360 GB. You can create a VM with a 2360 GB disk if available. Quantum recommends that you to create your BP-meta disk with as much capacity as you can afford, to reduce the need to plan for an additional or multi-step storage expansion. See Disk Provisioning Types.

  • For bulk storage it should be possible to configure a single 256 TB disk, if that capacity is supported by your hypervisor. See your hypervisor documentation regarding maximum disk capacity limits.

  • Your hypervisor may limit the number of disks allowed to be created on a single (virtual) SCSI controller, but you can add more than 1 virtual controller in your DXi system configuration. There is no limit to the total number of supported controllers or disks in the DXi.

  • To optimize performance, spread your disks over multiple data stores (VMware).

Your DXi VM capabilities and performance will vary, depending on your physical server and hypervisor. As with any VM, some options are to:

  • Add more CPU cores.

  • Add more memory.

  • Reduce the number of I/O streams to and from the VM.

  • Use thick-provisioned storage disks.

  • Use SSDs or NVMe for your storage disks.

  • Switch to a larger profile.

  • Reserve hypervisor memory exclusively for the V5000.

Note: Quantum does not recommend running multiple DXi systems on the same hypervisor. Running 2 or more DXi systems can result in I/O errors on the hypervisor. Use your hypervisor tools to monitor resource usage.