4 4 3 Beefalo:Drives
Drives are devices used for data storage that read from or write data to media. They are either local drives, connected to the SEP sesam Server, or remote drives, connected to another computer on the local or wide area network. These can be tape devices with removable tape cartridges or disk-based storage devices. Remote drives enable the storage devices, which are used by SEP sesam, to be distributed over WAN.
|It is recommended that SEP sesam auto-configures backup devices, but even for the automatically configured tape devices you should check their configuration and in some cases enable persistent naming to avoid errors in SEP sesam operation. For details, see Enabling persistent naming for tape devices.|
SEP sesam provides dynamic drive sharing option in SAN environments. Note that a proper SEP sesam SAN Dynamic Drive Sharing (SDD) license is required for each drive you intend to share. For more information, see List of Licenses.
Drive sharing option allows the drives to be available to multiple Remote Device Servers (RDS) at any time. A physical drive can be seen by any number of RDSs and can be used by relevant systems to store data. Shared drives can be defined by a unique drive designation. This means that multiple drives are labeled with the same device identifier, which is specific SCSI designation, for example: /dev/nst0 (Linux ), Tape0 (Windows). While executing SEP sesam tasks, such as backup and restore, the drives are being shared by multiple servers based on a shared timing.
SEP sesam enforces you to organize drives into different groups. Grouping the drives of the same type into one group facilitates and optimizes backup operation. SEP sesam selects which drive from the group will be used for running a backup job. A backup is performed automatically on the drive that is currently free. In the event of a drive failure, each backup is automatically executed on other available drives.
Even in case you have only one standalone drive, you have to create a drive group first and attach a drive to it. The drive group is directly connected to the media pool. By connecting a media pool to the drive group, you specify where to SEP sesam saves the backup. Later in the process when configuring a backup, you select a target media pool (which is already connected to the drive group) to which the data will be backed up by creating a backup event (where the connected drive group is determined automatically by media pool selection). For details on backup configuration, see Standard Backup Procedure.
By double-clicking the drive group or selected drive, its properties are shown and can be modified.
New drive group
The option New Group is used to configure a new group.
- Name: A meaningful name for the new drive group which is easily recognizable by administrators, support personnel, and users. This should be part of a general design that can be referred to and expanded at any time.
- Description: Additional information for the user, e.g., input of the loader's location and the relevant employee contact for assistance.
The option New Drive is used to configure a new drive. Each drive must be assigned to a drive group, therefore a drive group must be created first.
In the New Drive window, the following fields are available:
- Drive number: The number is automatically assigned by SEP sesam and determines internal number of the drive.
- Drive name: Optional description, e.g., logical identifier of a drive. In case of a shared drive within SAN, the name must be the same for all client shared drives, e.g., SAN-Drive-LUN-0.
- Drive type: Depending on storage type, the relevant drive type must be selected from the drop-down list.
- For tape drives, select the relevant tape type (LTO, DLT, SLR etc.).
- If you plan to use the drive in the virtual disk storage, select DISK_STORE. The data will be stored to SEP sesam data store.
- If the drive is removable media, select DISK_CHNG.
- Loader: Available options are No loader, 0 and 1. If the drive belongs to the loader, select 1. If it is a single tape drive, select No loader option. Number 0 defines the virtual loader.
- Drive no. in loader: Determines how the drives are used within the loader. It is set automatically by saving the new drive configuration. It can also be set manually, but it is strongly advised not to; this order depends on the hardware vendor's numbering scheme for all installed drives. If the order is entered incorrectly, SEP sesam will not be able to access the correct drive.
- Device server: The name of the server or RDS to which the drive is connected. The drop-down list displays all available hosts.
- Drive group: The relevant drive group have to be selected from the drop-down list of all available drive groups.
- Device (non-rewinding): Operating system specific SCSI designation for the device, for example: on Linux (/dev/nst0), on Windows (Tape0). If the drive is installed properly, you can determine its SCSI ID by using a SCSI loader utility slu topology which shows information about the loaders and drives connected to the system as well as their relation.
To list all attached SCSI devices, run slu topology:
<SESAM_BIN>/sesam/slu topology. For details on its usage, see Using slu topology for detecting devices.
Tip It is recommended that SEP sesam auto-configures backup devices, but even for the automatically configured backup devices you should check their configuration by using slu topology. SCSI addresses may be changed during reboots, especially in environments with several tape libraries attached to a server, and the operating system might mix the SCSI addresses between different loaders and library tape drives. Consequently, SEP sesam may have problems accessing devices. In such cases, consider enabling persistent naming. For details, see Configuring Loaders and Drives.
- Device Block Size: As of v. 4.4.3 Beefalo V2, it is possible to change the default write density for tapes to achieve better tape performance by using the Device Block Size option; see the below section Setting device block size.
- Tape in drive: If a medium is loaded into the drive, SEP sesam label is displayed.
- Information: If indicated, the messages from the drive hardware are displayed.
- Max. channels: The number of parallel streams that can be used during backup to the backup drive. The number of data streams available for backup depends on license.
For example, with SEP sesam ONE Server license only one backup stream is active. Multiple backup tasks are scheduled to start simultaneously, but will be performed one after another because of only one backup stream. In another example, SEP sesam Standard Server license is purchased for the environment that has has one disk drive and two tape drives attached. The SMS channels are connected to all drives. Multiple backup jobs (e.g., 10) are scheduled to start simultaneously. Backups may run in parallel to either one or both tape drives, but only 5 data streams are open for data transfer.
- Encryption capable: For already configured drives, it shows whether they are encryption capable. The field is shaded for new drives. Note that SEP sesam provides native support for managing LTO-based encryption; the LTO encryption of tape drives can be enabled on a media pool level. For details, see LTO Encryption.
- Click OK to configure the drive.
|With some drive types, such as DISK_CHNG, the name is automatically assigned based on disk + drive number.|
Setting device block size
As of v. 4.4.3 Beefalo V2, it is possible to change the default write density for tapes to achieve better tape performance by using the Device Block Size option in the drive properties. You can increase the tape block size if you are using LTO Ultrium tape drives and your backup environment supports larger tape blocks. Setting the device block size only applies to the LTO tapes when they are initialized; changing this setting cannot be applied for tapes which are still used for backups. For example, once EOM is reached, another tape is required and can be initialized by setting the desired tape block size (0 -> default block size).
The default block size value is 64 KB. If the Device Block Size option is set to 0, then the default block size is determined as follows:
- On Windows, the value is retrieved from the tape device driver.
- On Linux, the value is mapped to the LTO drive type, as shown in the table.
|LTO drive type||Value|
To set the tape block size, double-click the tape drive to open its properties. Then select the block size value from the Device Block Size drop-down list. You can increase the block size up to 1024 KB.
Manage multiple drives
Manage multiple drives option enables you to easier change drives properties (e.g., maximum number of parallel streams (max channels), delete drives, create new drives, etc). It lists all configured drives and allows you to change the properties settings of multiple drives, after which SEP sesam restarts the drives automatically. Whether only the modified drives will be restarted, depends on drive type.
- If a data store drives are being reconfigured, only the modified drives are restarted.
- Any change of a tape device drive results in restarting all configured tape drives.
Configure all drives
It is possible to reconfigure all drives by using Configure all drives option. Note that this action aborts all running backups, restores and migrations.