Hello, On 10/10/2006 11:30 AM, Anders Boström wrote: >>>>>>"AL" == Arno Lehmann <[EMAIL PROTECTED]> writes: > > > Hi! > > AL> On 10/10/2006 9:59 AM, Anders Boström wrote: > >>>>>>> "KS" == Kern Sibbald writes: > >> > >> > KS> From the statistics you show, the backup does not appear slow to > KS> me. The reason you might think it is slow is because you are > KS> comparing apples and oranges. > >> > KS> On the one hand, you measure the time to to a non-compressed tar > KS> on a local machine sending the output down an extremely hi-speed > >> bit bucket. > >> > KS> On the other hand, you measure the time of Bacula using > KS> compression sending real data to another process via TCP/IP (even > KS> though it might be on the same machine). > >> > KS> To do a better comparison, you could run tar including the z > KS> option so that it does compression. In addition, you should send > KS> the output of tar across the network and write it to either a file > KS> or a tape (whatever Bacula is using). > >> > >> You don't seem to have seen my data, so I state it again: > >> > >> bacula backup without SW compression: 1 hour 45 mins 2 secs > >> bacula backup with SW compression: 2 hours 42 mins 11 secs > >> local tar on the fileserver*: 53 mins 3 secs > >> > >> * time /bin/sh -c "tar cf - directory | cat >/dev/null" > > AL> Well, your tar does not create disk I/O for the data it "writes". > > >> bacula is ~2 times slower than the local tar without SW > >> compression. And, as stated already, the network isn't the limitation > >> (no TCP retransmission), neither is the backup-server (CPU and disc is > >> > >>> 98% idle during backup). > > AL> Still the network is being used and that always involves latencies, > AL> syncronization times, etc. > > Yes, and that might be the problem. But if it is about latencies > and/or synchronization, then it is a bacula performance problem!
No, what I'm talking about is network fundamentals. Whenever you send data across a network that takes time, and it takes more time than dividing xMBit/s by the amount of data. Always. > Is bacula limited in performance due to high latency? (Not that we > have that problem, but anyway...) > > Is bacula limited in performance due to synchronization? Networks are limited by several factors. That's not something you can fix, and network throughput is not normally the most limiting factor in a Bacula setup. > >> But, as you point out, the tar should be faster. It doesn't need to > >> write to net. However, not 2 times faster. The net-load is ~1% (10 > >> Mbit/s on a GE-network), and *should* not affect the performance in > >> this case. > > AL> *Should* is not very helpful here... instead, send the tar output > AL> through a netcat to the backup server and write it to disk. For example. > > But we have two scenarios here: > > 1. Bacula is affected by a very low network load. > > 2. Bacula isn't affected by a very low network load. > > If (1) is true, why??? Erm, no, I see no such scenario. I see you claim that a (mostly idle) network transfers data as fast as a tar > /dev/null which is not true. Try measuring. Arno > / Anders > > ------------------------------------------------------------------------- > Take Surveys. Earn Cash. Influence the Future of IT > Join SourceForge.net's Techsay panel and you'll get the chance to share your > opinions on IT & business topics through brief surveys -- and earn cash > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > _______________________________________________ > Bacula-users mailing list > Bacula-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/bacula-users -- IT-Service Lehmann [EMAIL PROTECTED] Arno Lehmann http://www.its-lehmann.de ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Bacula-users mailing list Bacula-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bacula-users
