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HPSS Prod2 Setup
hpss prod2 is a new HPSS setup that employs 1TB T10K data cartridges. The prod2 setup has
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23764091017 | 488 | 257 | 231 |
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Four files were read from the same tape. All file were between 1.1GB to 1.5 GB large. For the first file (most likely) the tape had to be remounted. The file was read twice the first time from disk and the second time from the disk cache. The figure below shows the effective transfer rates for the transfers and the time difference between reading from tape and disk (first-second). The position of the files on tape is also shown.
Reading sequentially all files from a tape
All 377 files were read from the tape H0000700, except the first file as this one was split across two tapes. One client was used to read the file sequentially. The checksum and size of the transfered files matched the ones obtained from the xrootd cluster.
The lower figure below shows the elapsed time for each transfer versus the file size. The blue line shows the relation between elapsed time and file size to be:
The 1.5 as well as the 45 approximate values.
The upper figure shows the elapsed time subtracted by the expected transfer time. The expected transfer time was assumed to be the file size divided by 45MB/s.
