Jeff Gustafson wrote:
On Fri, 2012-03-23 at 19:02 +0100, Christoph Bußenius wrote:
Hi,
maybe try "dsync -o mail_fsync=never".
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? ...Jeff
Next -- bench "cp -ax", against rsync -axHAX when it has to copy >75% of the data (cp ~6-8x speed). But for file speed, 'dd' is king, as it can use large buffers (~16MB gives best results on my local Gbit network), but it misses all those pesky acls and extended attrs, not to mention file perms...*sigh* Compare that to the I/O done 4k at a time by many older utils...
If I'm writing to the LOCAL HD, instead of the network, then a 1GB-4GB buffer size gives best results (1GB/s raid5). Small buffers are such a PITA!