HP StorageWorks 6000 HP StorageWorks VLS and D2D Solutions Guide (AG306-96028, - Page 185

Figure 81 VLS Sizing Example 3 . • Database Full Backup size 200TB - 1% change rate • File System Full backup Size 66.6 TB - This example replicates one of the incremental backups, size of 10% • Initial Replication Window 24 hours • Required Link 1100bit/sec + some margin for catch-up • Consider 1 Gb/sec link and relax replication window to 26 hours The final example shows the trade-off and the sheer capabilities of this technology. This simulates a 266 TB environment being replicated (200 TB database, 66.6 TB file system) with an initially stated 24 hour replication window (allowing four hours until the first replication starts). When you run the Sizer calculations in order to replicate this volume of data within 24 hours, it really needs a1200 Mbits/sec link (or 2 x 600 Mbits because few telcos deliver greater than a 1Gb/sec link). Again note how, because of the volume of data, the number of nodes has increased and the replication ability has also scaled appropriately. You now have a choice to either invest in the 2 x 600 Mbit/sec links or compromise on the time to data off-site. If you are willing to accept data replicated within 26.2 hours, you can save considerable cost in requiring only a 1 Gb/sec link. This example replicated the equivalent of 266 TB in just over 26 hours, a task that without deduplication technology would have taken 205 hours on DWDM 4Gb Fibre Channel at significantly higher cost. While some may say 1 GB/sec is not low bandwidth, everything is relative to the task at hand. Table 27 Summary of the Calculations Involved in the Sizing Examples Data types (3 DB:1 FS) & backup type Full size in GB Replicated data (compressed) in GB Time available to replication/time to replicate Link speed available or required in Mbit/sec Combined link speed Database (Full) 1% change 15000 198 File data (Full) 5000 297 24 hours 83 at 40% utilization 125 at 40% utilization 20 Mbits/sec at 40% utilization HP StorageWorks VLS and D2D Solutions Guide 185