On Sat, 2012-03-24 at 14:21 +0100, Maarten Bezemer wrote:
On Fri, 23 Mar 2012, Jeff Gustafson wrote:
That didn't seem to make much of a difference. On a 3.1GB backup it shaved off 5 seconds. dsync's time was over 6 minutes with or without the mail_fsync=never. rsync copied the same 3.1GB mailbox in 15 seconds. It seems to me that dsync *should* be able to be just as fast, but it currently is spending way too much time doing something. What is it?
Syncing 3.1GB in 15 seconds would require a speed of more than 200MB per second. Depending on the harddisks used, that would be quite a challenge. If you use rsync to only transfer the files that changed (based on file modification time) you may or may not miss files that have changed but still have the same time stamp. I assume you didn't use the --checksum parameter to rsync, right?
The destination directory was empty. I was doing a full backup.dsync does so much more than simply copy some files...
I realize that. I am hoping that the extra data that dsync hasavailable to it would improve the speed of syncing backups. My baseline
testing of simply backing up a mailbox to an empty directory shows that
dsync is takes way too long to backup a single mailbox. I have over a
terabyte of data to backup.
I'm currently using rsync and it must traverse tens of thousands of
files and check the time information. It works, but I was hoping dsync
would be a better solution. dsync should be able to sync faster, by
gulping in the index information for each mailbox. I haven't even moved
to the point of sync'ing since the baseline test of simply exporting a
mailbox is so slow.
...Jeff