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Date: | Sat, 11 Jul 2015 05:38:38 +0300 |
From: | Andrey Repin <anrdaemon AT yandex DOT ru> |
Reply-To: | cygwin AT cygwin DOT com |
Message-ID: | <1023815842.20150711053838@yandex.ru> |
To: | Warren Young <wyml AT etr-usa DOT com>, cygwin AT cygwin DOT com |
Subject: | Re: Telnet / SSH connection timeout on LAN |
In-Reply-To: | <5C24455B-3D28-4C6D-A77B-70BB5D67F0AA@etr-usa.com> |
References: | <1436142936994-119480 DOT post AT n5 DOT nabble DOT com> <7931485F-EEA3-4C1B-8B2C-E495EF5ED1A9 AT etr-usa DOT com> <1283519593 DOT 20150709090453 AT yandex DOT ru> <5C24455B-3D28-4C6D-A77B-70BB5D67F0AA AT etr-usa DOT com> |
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Greetings, Warren Young! > On Jul 9, 2015, at 12:04 AM, Andrey Repin <anrdaemon AT yandex DOT ru> wrote: >> >>> rsync requires a pretty heavy network transaction to figure >>> out if files have changed. >> >> I'm rsync'ing about 15 gigabytes of my home directory with just a few megs of >> network exchange. > “Just?” > That was my definition of “heavy”. Sorry, but you can't sync data without sending data. And these few megs is the actual data I generate daily. > Consider all the disk I/O required. In its default mode, rsync must do a > full directory tree scan on the directory to be transferred, on *both* ends. > For each file with a different mtime or size, it must then recompute all the > hashes in that file, again on both sides. Wrong. In default mode, rsync only care about timestamp and size. It will not go on hashing crusade unless explicitly told to. > Can you really handwave away megs of network I/O and potentially gigs of > disk I/O? Do you never use locate(1) instead of find(1)? Same issue. I normally know where my stuff is, so I don't need to `find` or waste space on `locate` hash tables. > On top of that, the OP wants to do this every time the machine becomes > idle. Even if it was idle a few seconds ago, did some work, and is idle > again, the OP wants all this work to be done all over again. > Horribly wasteful. > I believe Dropbox and its major competitors avoid the need for this tree > scan by hooking into the OS’s filesystem change notification API, so that > they don’t do any network or disk I/O until one of the files it is responsible for changes. > That’s the right way. VSS would be the right way, but I still did not find time to research its extents. -- With best regards, Andrey Repin Saturday, July 11, 2015 05:35:21 Sorry for my terrible english...
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