Hi, Thank you, Rudolf. This is very useful information! Thank you for taking effort to benchmark this.
Best, Ivan On Friday, June 23, 2017 03:53:04 PM Cejka Rudolf wrote: > Cejka Rudolf wrote (2017/06/05): > > Cejka Rudolf wrote (2017/06/02): > > > Ivan Adzhubey wrote (2017/06/01): > > > > b) What is the effect of MaximumFileSize option and what would be its > > > > optimal value for my IBM LTO-5 SAS drives? I have used 8GB value > > > > found in one of the list posts, while the documentation suggests 2GB > > > > for LTO-4. But even set at 8GB this would create lots of EOF marks on > > > > a 1.5TB tape, do we really need so many? > > > > > > Hi, I do use 16 GB. Every EOF mark means around 3 seconds delay. So if > > > you have over 200 files on the tape using 8 GB, it is around 10 minutes > > > extra per tape.> > > Hi, small fix. It seems that it is even around 5-6 seconds delay resulting > > in extra 20 minutes per tape. And worse, I'm afraid that the tape drive > > do not stop nor slowdown tape movement, which would mean over 10 % of the > > tape lost because of filemarks. Hope that I'm wrong. > > Hi, I finally have done and finished real testing with Maximum File Size > option. Tested on LTO-6 drive with LTO-5 tape, so the results are relevant > for LTO-5, used btape utility and fill s (simplified) command. > > Fortunately, I has negligible impact on tape capacity, but unfortunately, I > has really dramatical impact on overall write speed and you have to count > not just 5-6 seconds, but better 8-10 seconds per file. I also added time > to read one file at 140 MB/s, which is important for seeking during > restores. > > File Simplified Simplified Bytes Files Rough time to > size fill time fill rate written written read one file > > 1 GB 6:44:18 61.8 MB/s 1498688192512 1499 00:00:07 > 2 GB 4:51:30 85.7 MB/s 1498737278976 750 00:00:14 > 4 GB 3:54:57 106.3 MB/s 1498762641408 375 00:00:29 > 8 GB 3:24:22 122.2 MB/s 1499224932352 188 00:00:57 > 16 GB 3:11:09 130.7 MB/s 1499456405504 94 00:01:54 > 32 GB 3:04:35 135.4 MB/s 1499690303488 47 00:03:49 > 64 GB 3:01:17 137.8 MB/s 1499574960128 24 00:07:37 > 128 GB 2:59:37 139.1 MB/s 1499603664896 12 00:15:14 > > And it seems that the results are perfectly reproducible. Three successive > tests with 16 GB file size have had exactly the same fill time 3:11:09! > Tests were done by mistake, when I wondered how it is possible that the > time stays exactly the same :o) > > Regards. The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
