Preparing Magneto-Optical (MO) Disks

TurboSTORE/iX II and TurboSTORE/iX 7x24 True-Online Backup support the use of HP magneto-optical (MO) devices. The MO devices currently supported include product numbers:

C1700A
C1700T
C1708T
C1100B




	NOTE: After MPE/iX Release 5.5, TurboSTORE/iX II and TurboSTORE/iX 7x24 True-Online Backup will only support the above three devices. New MO devices will not be supported.

Check with your HP representative or the HP 3000 Configuration Guide for the most recent information on what types of MO devices are supported by TurboSTORE.

Use of magneto-optical disk is recommended for the daily backup of large amounts of data. When TurboSTORE/iX's low data compression is used during a magneto-optical backup, the capacity of the MO device is increased to almost 40 Gbytes of data and the potential backup rate is increased to up to 2.8 Gbytes per hour.

When high compression is used, the capacity of each MO device is increased to almost 64 Gbytes of data. Note, however, that compression ratios depend on the data being stored, and may be lower than or exceed these capacities.

Preparing for Backup to Optical Disk

When using MO devices, it is important that you ensure that enough scratch media is mounted before you issue the STORE command. The media preparation tasks are performed using the Magneto-Optical Utility (MOUTIL), a utility program provided with MPE/iX. Use of the MOUTIL program is documented in the Magneto-Optical Media Manager User's Guide (36398-90001).

Determining the Number of Disks Needed

You should compute the number of disks needed for a backup by dividing the total number of sectors to be stored by the capacity of one MO disk surface. For example, each single density optical disk surface can hold approximately 290 MBytes of uncompressed data (depending on the type of data and assuming there are no bad sectors on the disk). By comparison, 2400 feet of 1/2 inch backup holds approximately 140 MBytes of data. Therefore, one optical disk surface is equivalent to approximately two tapes. If your backup normally takes four magnetic tapes, plan on using two optical disk surfaces.

Again, using single density disks as an example, you could estimate the number of optical disk surfaces needed by dividing the total amount of disk sectors in use to be stored by 1,187,840.

First, use the DISCFREE command to determine the amount of disk sectors in use on your system. For example:

Figure 3-11 DISCFREE

    :DISCFREE E,101

 

   DISCFREE A.01.03 Copyright (C) Hewlett-Packard 1989.  All rights reserved.

                            WED, OCT 31, 1990, 04:59 AM

    

              |    Configured     |      In Use       |     Available     |

   -----------+-------------------+-------------------+-------------------+

 

   TOTALS : 

    Device    |    4464384        |    3136672 ( 70%) |    1327712 ( 30%) |

    Permanent |    3906336 ( 88%) |    3002160 ( 67%) |     904176 ( 20%) |

    Transient |    3348288 ( 75%) |     134512 (  3%) |    1327712 ( 30%) |

In this example, a total of 3,136,672 sectors are in use.

Divide the total number of sectors to be stored by 1,187,840 and round up to the nearest whole number to determine the number of disk surfaces required.
3136672 / 1187840 = 2.6 disk surfaces
In this example you would need three disk surfaces.

Remember to use the actual capacity of your MO disks when doing these computations.

Specifying the Magneto-Optical Device

When storing to a magneto-optical device, you do not use file equations as you do when using backup drives. Nor do you use the STORESET parameter to backreference the device. Instead, you specify the devices to be used for a MO backup through the MOSET parameter of the STORE command. Specify the LDEV number of the magneto-optical device as a parameter to MOSET. For example:

   ;MOSET=(101)

   ;MOSET=(MO)




	NOTE: Actual LDEV numbers are only necessary if you have multiple magneto-optical devices and you want to specify a particular magneto-optical device. Using the keyword "MO" instead of a number causes `STORE` to use the first available scratch media.

Naming the Backup

You can optionally use the NAME parameter of the STORE command to name the backup with a name that logically relates the media as being from the same backup. The name specified must be unique so that it can be found when restoring files. For example, a monthly backup for September, 1990 on a system called "KING" could be named "MONTHLY.SEPT1990.KING". Note that the backup name is a three-field name separated with periods. Each of the three fields can be up to eight alphanumeric characters. If a backup name is not specified, a default name is created using the time, date, and system name. For example, "BK1130PM.D23OCT90.KING".




	NOTE: The backup name must be unique for `RESTORE` to be able to find it.

If media is removed from the magneto-optical device, use an external label with the same backup name as you specified with the STORE command.

The media subname of the MEDIASUB parameter to the MOUTIL command SCRATCH is used to hold the media number and set number for each side of the media.

Storing to a Single Magneto-Optical Device

The following example illustrates the STORE command to backup files to a single magneto-optical device with the LDEV number 101.

   :STORE @.@.@;;MOSET=(101);SHOW;NAME=BK1130PM.D23OCT90.KING

Storing to Multiple Magneto-Optical Devices

Multiple magneto-optical devices can be used in parallel (sequential use is not supported) for backup by specifying each magneto-optical device drive with the MOSET parameter. For example, to use LDEV 102 and 103 in parallel, the MOSET entry would be:

   ;MOSET=(102),(103)

For example, to use the first available media in parallel, the MOSET entry is:

   ;MOSET=(MO),(MO)

Do not mix alphanumeric with numeric allocation requests. For example:

   ;MOSET=(M1),(102)

Preparing Magneto-Optical (MO) Disks

Technical documentation

» Table of Contents

» Glossary