Storage management

You can configure and administer storage pools for a vSnap server.

Managing disks

vSnap creates a storage pool using disks provisioned to the vSnap server. In the case of virtual deployments, the disks can be RDM or virtual disks provisioned from datastores on any backing storage. In the case of physical deployments, the disks can be local or SAN storage attached to the physical server. The local disks may already have external redundancy enabled via a hardware RAID controller, but if not, vSnap can also create RAID-based storage pools for internal redundancy.

Disks that are attached to vSnap servers must be thick provisioned. If disks are thin provisioned, the vSnap server will not have an accurate view of free space in the storage pool, which might lead to data corruption if the underlying datastore runs out of space.

If vSnap was deployed as part of a virtual appliance, it already contains a 100 GB starter virtual disk that can be used to create a pool. You can add more disks before or after creating a pool and accordingly use them to create a larger pool or expand an existing pool. If job logs report that a vSnap server is reaching its storage capacity, additional disks can be added to the vSnap pool. Alternatively, creating new SLA policies will force backups to use an alternate vSnap.

It is essential to protect against corruption caused by a VMware datastore on a vSnap server reaching its capacity. Create a stable environment for virtual vSnap servers that do not use RAID configurations by utilizing thick provisioned VMDKs. Replicating to external vSnap servers provides further protection.

A vSnap server will become invalidated if the vSnap pool is deleted or if a vSnap disk is deleted in a non-redundant RAID configuration. All data on the vSnap server will be lost. If your vSnap server becomes invalidated you must unregister the vSnap server using the IBM Spectrum Protect Plus interface, then run the maintenance job. Once complete, the vSnap server can be re-registered.

Managing encryption

To enable encryption of backup data on a vSnap server, select Initialize with encryption enabled when you initialize the server. Encryption settings cannot be changed after the server is initialized and a pool is created. All disks of a vSnap pool use the same encryption key file, which is generated upon pool creation. Data is encrypted when at rest on the vSnap server.

vSnap encryption utilizes the following algorithm:

Cipher name: Advanced Encryption Standard (AES)
Cipher mode: xts-plain64
Key: 256 bits
Linux Unified Key Setup (LUKS) header hashing: sha256

Managing encryption keys

The disk encryption key files generated upon pool creation are stored under the directory /etc/vsnap/keys/ on each vSnap server. For disaster recovery purposes, back up the key files manually outside the vSnap server. After a pool is created, use the following commands as the serveradmin user to copy them to a temporary location and then copy them to a desired, secure backup location outside the vSnap host.

mkdir /tmp/keybackup-$(hostname)

sudo cp -r /etc/vsnap/keys /tmp/keybackup-$(hostname)

Detecting disks

If you add disks to a vSnap server, use the command line or the IBM Spectrum Protect Plus user interface to detect the newly attached disks.

Command line: Run the vsnap disk rescan command.

User interface: Click System Configuration > Backup Storage > Disk in the navigation pane, and then click the Actions menu next to the relevant vSnap server and select Rescan.

Showing disks

Run the vsnap disk show command to list all disks that are on the vSnap system,

The USED AS column in the output shows whether each disk is in use. Any disk that is unformatted and unpartitioned is marked as unused, otherwise they are marked as used by the partition table or file system that is discovered on them.

Only disks that are marked as unused are eligible for creating or adding to a storage pool. If a disk that you plan to add to a storage pool is not seen as unused by vSnap, it might be because it was previously in use and thus contains remnants of an older partition table or file system. You can correct this by using system commands like parted or dd to wipe the disk partition table.

Showing storage pool information

Run the vsnap pool show command to view information about each storage pool.

Creating a storage pool

If you completed the simple initialization procedure described in Completing a simple initialization, a storage pool was created automatically and the information in this section is not applicable.

To complete an advanced initialization, use the vsnap pool create command to create a storage pool manually. Before you run the command, ensure that one or more unused disks are available as described in Showing disks. For information about available options, pass the --help flag for any command or subcommand.

Specify a user-friendly display name for the pool and a list of one or more disks. If no disks are specified, all available unused disks are used. You can choose to enable compression and deduplication for the pool during creation. You can also update the compression/deduplication settings at a later time by using the vsnap pool update command.

The pool type that you specify during the creation of the storage pool dictates the redundancy of the pool:

raid0: This is the default option when no pool type is specified. In this case vSnap assumes your disks have external redundancy, for example, if you use virtual disks on a datastore backed by redundant storage. In this case, the storage pool will have no internal redundancy.; Once a disk has been added to a raid0 pool it cannot be removed. Disconnecting the disk will result in the pool becoming unavailable, which can be resolved only by destroying and recreating the pool.
raid5: When you select this option, the pool is comprised of one or more RAID5 groups each consisting of three or more disks. The number of RAID5 groups and the number of disks in each group depends on the total number of disks you specify during pool creation. Based on the number of available disks, vSnap chooses values that maximize total capacity while also ensuring optimal redundancy of vital metadata.
raid6: When you select this option, the pool is comprised of one or more RAID6 groups each consisting of four or more disks. The number of RAID6 groups and the number of disks in each group depends on the total number of disks that you specify during pool creation. Based on the number of available disks, vSnap chooses values that maximize total capacity while also ensuring optimal redundancy of vital metadata.

Expanding a storage pool

Before expanding a pool, ensure that one or more unused disks are available as described in Showing disks.

Use the command line or the IBM Spectrum Protect Plus user interface to expand a storage pool.

Command line: Run the vsnap pool expand command. For information about available options, pass the --help flag for any command or subcommand.

User interface: Click System Configuration > Backup Storage > Disk in the navigation pane. Click the manage icon the user icon for a vSnap server to manage it, and then expand the Add New Disks tab. The tab displays all unused disks discovered on the system. Select one or more disks and click Save to add them to the storage pool.