The tables below show backup throughputs which can actually be achieved with LTO-6 tape devices under FDDRL on /390 and x86 systems. In each case a DUMP and RELOAD to one volume was performed with files permitting average compression (factor 2-3).
The throughput rates specified refer to one task during the actual backup and restoration phase, in other words without mounting the tape, without starting and ending the programs, and without any other overhead.
The throughputs were measured using a number of configurations, with the following hardware components being used:
Servers: SE700-20 with 1,120 RPF and SE300-80F with 1,200 RPF
Storage systems: ETERNUS DX600 S3 and ETERNUS DX440 S2
SAN connection of the storage systems: 2-3 Fibre Channels operating at 8 Gbit/s
Volumes: Different-sized NK2 volumes on RAID 1/0 (3+3)
Tape devices: IBM ULTRIUM-TD6 connected to a Fibre Channel operating at 8 Gbit/s
In practice, the throughputs which can be achieved depend on the sum total of the components involved. No generalization is therefore possible for throughputs in specific individual cases. Instead, the bandwidth of the throughputs measured is specified. The throughputs achieved with servers with /390 and x86 architecture are at a comparable level when the same performance is available.
Throughput with FDDRL in Mbyte/s | Throughput with FDDRL in Mbyte/s |
270-310 | 310-320 |
In order to display the CPU requirement on a comparable basis, the CPU utilizations measured were converted to RPF per Mbyte/s. The CPU requirement with an FDDRL task is between 0.1 and 0.15 RPF per Mbyte/s. Consequently, a fictitious system with 500 RPF, for instance, would have a workload of between 5% and 7.5% with a data throughput of 250 Mbyte/s.
The I/O processors of BS2000 servers in no way present a bottleneck.