I've set up a 1GB tmpfs filesystem on a system with a single IDE disk and 2GB's of memory. I'm storing a large amount of RRD files (~300MB) on the tmpfs filesystem to make their generation a bit speedier... this part works great.
However, I want to rsync these files over from time to time to a directory on the local filesystem (same physical server). I'm using rsync 2.6.4pre3 and am hoping to understand a bit better what is happening. When I run rsync -av /path/to/tmpfs /path/to/diskdir things move along pretty fast for while, then there's a big pause... sometimes for up to 30+ seconds where nothing seems to be happening, but all IO on the system ceases (can't do anything in another xterm). Then rsync starts moving along again for a while, and then pauses again... after about three such pauses it finishes the entire rsync process. I'm wondering what I can do to speed things up... perhaps whatever processes that write to the tmpfs filesystem are fighting with rsync... but doesn't rsync just need read access? I've also tried with -W (copy whole file) and used a smaller -B value. Anyways, I'll explain a bit about the curren scenario: 1. Daemon on system receives data from remote devices. 2. Daemon calls rrdtool to write a .rrd file to the tmpfs filesystem. 3. rsync runs periodically (every 5 minutes) to sync up the tmpfs filesystem with a directory on the local filesystem. The tmpfs filesystem is a directory with about 100 directories inside of it, each containing rrd files. I'm considering using a script to just rsync one of these subdirectories at a time over a period of time to "distribute" the load. The main issue is that while rsync is running and enters these random 30 second "pauses", no IO can happen and things get really backed up on the system and it ends up being faster for me to just dump the tmpfs completely and go back to writing directly to disk as slow as that was... Any suggestions? -- Ray Van Dolson Linux/Unix Systems Administrator DigitalPath Networks -- To unsubscribe or change options: https://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
