%META:TOPICINFO{author="ChrisBartram" date="1147831287" format="1.1" version="1.1"}%
%META:TOPICPARENT{name="Hp3000DdsUnits"}%
Testing that we performed on backup technologies yielded the following results: 

A HP7980XC delivers backup rates of approximately 600-650 KBS. A DAT drive delivers backup rates of approximately 300-350 KBS. 

The testing was performed on a standalone HP3000 960 dedicated to the test. All stores were performed with TurboSTORE. The data was a copy of actual production data and spanned multiple tapes. 

The HP7980XC was attached to a dedicated HP-IB card to ensure that the tape would operate in stream mode. Our testing indicates that 2 HP7980XCs can be connected to each HP-IB card and maintain stream mode. Data storage rates were approximately the same whether the drive was in hardware compression mode or not. 

The DAT drive was attached to a dedicated SCSI card. Several DAT drives were tested. The transfer rates were approximately the same but amount of data stored varied. 

Time for reel changes were not included in the transfer rate calculations even though it impacts the backup time. 

 --[[SteveCole]]

We need to be a bit more specific about what rates and tape drives are wanted. RE HP DDS drives (note DDS is a subset of DAT) the 60 Meter and 90 M drives have a native transfer rate of 183KBytes/sec. The new 120 M drives have a 510KB/sec rate. The 7980's rate is 781KB/sec. 

But for Backups using HP TurboStore (or other products) the capacity of the tape media, mounting and rewind times, channel capacity and usage, and compressibility of the data, and who does the compressing (hardware or software) must be considered. 

For an actual data point, I have a 3000/947 which backs up about 17 million sectors (4.3 Gbytes) and it takes about 3.5 hours with software compression to a 90 M DDS. It uses about 2.4 hours to a 120 DDS with hardware compression. That is 1.25 GB/Hour and 1.83 GB/hr respectively. This may be somewhat limited by the tape and discs being on the same SE SCSI interface. Note that this is a low compression ratio as if I add only a few more files to the backup the 90 M DDS goes to two tapes. 

For one reel STOREs the 7980XC is faster, but for the storage and convenience of one reel Full Backups, DDS with compression is King.

 --[[JamesOverman]]


-- Main.ChrisBartram - 17 May 2006