[ale] rsync comparisons

[Robert Coggins]

Well, I have the sync running within a respectable amount of time.  The
first way I was running the rsync was taking over an hour:

rsync -a --delete --exclude=afolder /path/a /path/b
where /path/a is an nfs mount on a SAN and /path/b is an nfs mount on a
server

But now with the following I am down to about 5 minutes:

rsync -a -e ssh --delete --exclude=afolder /path/a server:/real/path/b

Any ideas why this is going so much faster?

Thanks!
Rob

On 4/1/10 4:50 PM, Björn Gustafsson wrote:
> Oh, worst-case scenario: millions of files and NFS.  The overhead from
> NFS stat() calls is probably 95% of your time.  If you can run where
> *one* of the directories is on a local drive, that'll probably nearly
> double the speed.
> 
> On Thu, Apr 1, 2010 at 3:56 PM, Robert Coggins <ale at cogginsnet.com> wrote:
>> looks like it but they are 2 nfs mounts on one box.
>>
>> On 04/01/2010 03:55 PM, Jeff Hubbs wrote:
>>> Is this a box-to-same-box rsync?
>>>
>>> On 4/1/10 3:29 PM, Robert Coggins wrote:
>>>> I am using -a --delete and --eclude.  Pretty Basic.
>>>>
>>>> To be honest I think my problem is with the Source.  It even does an ls
>>>> very slow.  There are probably more than 1 million files in this 20GB.
>>>>
>>>> On 04/01/2010 02:49 PM, Björn Gustafsson wrote:
>>>>
>>>>> Which switches are you using now?  It doesn't sound like adding the
>>>>> ones discussed so far will help.
>>>>>
>>>>> On Thu, Apr 1, 2010 at 11:41 AM, Robert Coggins<ale at cogginsnet.com>  wrote:
>>>>>
>>>>>> Well, what I a seeing is the syncing of roughly 20GB taking over an hour
>>>>>> for just a few megs of differences.  It stays in the "building file
>>>>>> list..." for almost all of this time.  I am trying to find a way to
>>>>>> speed that up.
>>>>>>
>>>>>> Rob
>>>>>>
>>>>>> On 04/01/2010 11:37 AM, scott wrote:
>>>>>>
>>>>>>> rsync compares on a file level BUT it compares timedate stamps/sizes
>>>>>>> in "quick mode" (which is default).  but if you want it to compare
>>>>>>> file to file, use "-c or --checksum" option.  Now this puts a heavier
>>>>>>> load on both systems, since it does a MD5 checksum on every file that
>>>>>>> has the same timedate stamp/size on both sides of the sync.  Now if
>>>>>>> you want to force the copy of the whole file instead of the changed
>>>>>>> blocks, use the --whole-file option with it.
>>>>>>>
>>>>>>> I would use this ( -c&  --whole-file) sparingly.  It is going to slow
>>>>>>> down the copies, put heavier loads on both ends and transfer more data
>>>>>>> (control data) back and forth.  I dont know your situation so I cant
>>>>>>> say to use it or or not.
>>>>>>>
>>>>>>> scott
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Apr 1, 2010 at 11:00 AM, Robert Coggins<ale at cogginsnet.com>  wrote:
>>>>>>>
>>>>>>>> Is there a way to do file level comparisons and not block level
>>>>>>>> comparisons using rsync?
>>>>>>>>
>>>>>>>> Rob
>