Dear bacula users, I recently recognized that my tape drives do not perform as expected. Neither while used with bacula nor native with dd. I did many performance tests in the meantime but could not figure out the reason. So may I ask in this group what typical write speeds you have with your tape drives?
I tested LTO6 (IBM Ultrium HH6) and LTO4 (Ultrium 4-SCSI). Both are part of two libraries connected via SAS to a LSI SAS3801E-controller. The host system runs SLES12. I used btape and dd for writing. I figured out the best writing performance with blocksize 512KB (LTO4) resp. 2MB (LTO6). Both drives with compression on. LTO4 best performance (writing zeros): 115 MB/s LTO4 worst performance (random data): 71.58 MB/s LTO6 best performance (zeros): 153 MB/s LTO6 worst performance (random): 58 MB/s Disabling compression does not change the maximum speed. In this case writing zeros is the same as writing random date (expected). According to Wikipedia, theoretical speed should be LTO4: 240 resp. 120MB/s LTO6: 400 resp. 160MB/s Any ideas welcome! Thanks in advance! -- Kind regards Christoph _________________________________________ Christoph Litauer Uni Koblenz, Computing Centre, Office A 022 Postfach 201602, 56016 Koblenz Fon: +49 261 287-1311, Fax: -100 1311 ------------------------------------------------------------------------------ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
