https://bugzilla.samba.org/show_bug.cgi?id=3461
------- Comment #2 from [EMAIL PROTECTED] 2006-01-28 16:45 MST ------- I was a bit unclear, it's not that it's just a different device, it's a different physical disk. For a dataset of about 45GB we see an rsync time of about 2 hrs. When we use a temp-dir on another disk it drops to about 30 minutes. We have measured it and traced the performance problem down to the following: When the temporary file is on the same disk as the target, rsync must read the old file and the network, it also must write the temporary file, to the same disk as it reads from. It turns out that both the read and write speed of the disk drops substantially compared to separate disks. This is probably because the disk head needs to move between reads and writes, it doesn't move infinitely fast. With separate disks, there's a single-stream read from one disk and a single-stream write to the other disk. When copying afterwards, it's still single-streams to each disk, and we get close to 40MB/s. When we do intertwined reads and writes to the same disk, we get far less, in some cases only 5MB/s. Even with the extra copy, the dual-disk solution runs faster, the only problem being non-atomicity. -- Configure bugmail: https://bugzilla.samba.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the QA contact for the bug, or are watching the QA contact. -- To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
