Hi Bacula community On the search for bottlenecks in our new backup system (Bacula 5.2.10 on Ubuntu 12.04 64bit, HP Ultrium LTO-5 drive connected by Adaptec 1045 external SAS, File pool storage on iSCSI target) I ran the "speed" tests with "btape /dev/nst0" because the backups from local disk spool to tape only run with 70-80 MB/s.
Block size is default 64512 bytes and I have set Maximum File Size = 8GB so that the drive should not stop the tape too often. Summary of the first two tests: - Fastest zero test (4.295 GB): 178.9 MB/s - Fastest random data test (4.295 GB): 119.3 MB/s What I don't understand is the result of the next two tests (with bacula block structure): - Fastest zero test (4.294 GB): 84.21 MB/s - Fastest random data test (4.294 GB): 81.03 MB/s Is this normal? LTO-5 should have a speed of max. 140 MB/s with "uncompressable" data and a speed of max. 280 MB/s with 2:1-compressable data. Well, the test with random data gives ca. 120 MB/s I guess that's ok, but why does the bacula structure test with random data give only ca. 81 MB/s? The btape "fill" test also gives 81 MB/s with an LTO-5 tape. It fills up to 1.5 TB which is normal capacity with uncompressable random data but the write speed is much lower than expected. For comparison, I ran a dd test with /dev/urandom data and it shows that the drive is capable of reaching much higher speed than with bacula: root@bacula:/mnt/data1/tmp# dd if=urandom.raw of=/dev/nst0 bs=64k 196608+0 records in 196608+0 records out 12884901888 bytes (13 GB) copied, 112,333 s, 115 MB/s The full btape speed test output can be found here: http://paste.ubuntu.com/1071093/ Greets, Mario ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
