User manual HP COMPAQ STORAGEWORKS TL895 DLT LIBRARY ADDING THE TL895 TO THE ENTERPRISE BACKUP SOLUTION

[. . . ] Adding the TL895 to the Enterprise Backup Solution TechNote Notice The information in this publication is subject to change without notice. COMPAQ COMPUTER CORPORATION SHALL NOT BE LIABLE FOR TECHNICAL OR EDITORIAL ERRORS OR OMISSIONS CONTAINED HEREIN, NOR FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING FROM THE FURNISHING, PERFORMANCE, OR USE OF THIS MATERIAL. THIS INFORMATION IS PROVIDED "AS IS" AND COMPAQ COMPUTER CORPORATION DISCLAIMS ANY WARRANTIES, EXPRESS, IMPLIED OR STATUTORY AND EXPRESSLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR PARTICULAR PURPOSE, GOOD TITLE AND AGAINST INFRINGEMENT. This publication contains information protected by copyright. [. . . ] Differential backups back up all the data that has changed since the last full backup. s Procedure 1. Determine the number of full, incremental, and/or differential data sets to be retained. Assign percentages to each backup set for a given number of days. For example: Full (F) = 100% Incremental (I) = 20%* Differential (D) = 20%* *NOTE: Actual Incremental and Differential percentages vary for every backup set, based on the actual amount of data changed. 3. Calculate total storage needed: Total Percentage * Data Set (in GB) = Total Storage Needed (in GB) 5. Calculate storage capacity of each tape: Performance and Sizing 31 Calculating Backup Windows s Volume Calculations--Backup windows can be set at virtually 24 hours per day with the EBS due to the use of a separate Storage Area Network (SAN) for data movement. However, many administrators prefer to schedule backups at off hours for management reasons. To calculate the time needed to perform various backup jobs, the backup rate, as defined in the Backup Formula section, must be compared to the data sets being backed up. Tape Change Adjustment--Backup windows are determined by the total elapsed time required to backup sets of data. The number of DLT Drives can be increased by adding Tape Libraries to the EBS to meet the most demanding needs. A 3% reduction in performance should be applied to all backups that exceed the volume of one tape. Incremental or Differential Adjustment--Incremental and differential backups must compare archive bits of all files in the 180 GB data set and only back up the files that have changed since the last differential or full backup. A 14% reduction in performance should be applied to all Incremental and Differential backups. IMPORTANT: Real world effects on Incremental and Differential backups will vary depending on the percentage of changed files in each data set. s s More Information For detailed information and data for Lights Out testing see the whitepaper entitled Sizing the Compaq StorageWorks Enterprise Backup Solution (Part Number ECG551/0399) at: http://www. compaq. com/support/techpubs/whitepapers/. 32 Adding TL895 Libraries to the Compaq Enterprise Backup Storage System Sizing Calculations Before you can begin the sizing process, you must have a thorough understanding of the network, the type of data to be backed up, and the back-up window parameters. The easiest and most precise way to size an Enterprise Backup System is to use the Compaq StorageWorks Enterprise Backup Solution sizer software, which may be obtained from the Internet at http://www. compaq. com/products/storageworks/ebs/ebstoolsbackupsizing. html. If you do not have access to the software, the whitepaper entitled Sizing the Compaq StorageWorks Enterprise Backup Solution (Part Number ECG551/0399) found at: http://www. compaq. com/support/techpubs/whitepapers/ will walk you through the manual sizing process. Calculate Number of DLT Drives Needed 4. Determine Number of Libraries Needed Performance and Sizing 33 Sizing the Enterprise Backup Solution Speed Tests Determining the speed of Backup and Restore processes in a real-world environment is the most important factor in designing and implementing the Compaq StorageWorks EBS. Fibre Channel is designed to produce a theoretical maximum of 1. 0625 Gigabits per hour. This equates to 100 Megabytes per second or 360 Gigabytes per hour. (Test results are expressed in GB/H for clarity). IMPORTANT: A single DLT 7000 drive is rated at a theoretical maximum of 18 GB/H. To determine the approximate speed of backup and restore jobs in an EBS environment, Compaq began testing non-compressible (1:1) data. IMPORTANT: Compaq tested both the Seagate Backup Exec and Computer Associates (CA) ARCserveIT in an EBS environment to benchmark the DLT performance. Both Seagate and CA generated consistent throughput of approximately 15 GB/H. Tests were performed with each job configured to write to a single DLT drive. The TL895 supports seven DLT 7000 tape drives. 1:1 Backup & Restore Backup Restore 120 109. 16 Gigabytes Per Hour 100 89. 49 74. 25 59. 70 58. 14 44. 77 44. 88 29. 93 29. 97 14. 87 14. 76 1 2 3 4 5 6 7 80. 36 69. 87 90. 15 80 60 40 20 00 0 Number of DLT Drives Figure 4-1. [. . . ] This could mean that it has been physically disconnected or that errors are occurring on the FC-AL at a great enough frequency to prevent the device from maintaining login. If there are a large number of errors occurring in the FC-AL, the Fibre Channel Host Controller may not be able to communicate with the Fibre Channel Tape Controllers on the FC-AL. In this case, the Fibre Channel Controllers may appear to be offline in the program, although in reality they are physically connected to the FC-AL. When a FC-AL shows errors, the Fibre Channel Array and Tape Controllers may alternate between being logged-on the FC-AL or missing. Figure 6-17. [. . . ]