Right. So the answer to that is: It can, and does, but it is missing the obvious optimization of skipping the network stack for local-disk-to-local-disk transfer.
It might still be fast (enough); you'd have to benchmark it to see. See below for demonstration. Its pretty convenient to try local-to-local, because when jcp detects it is doing a local disk-to-local disk transfer, it starts the receiver for you (the jsrv part is run in-process, on a goroutine). It already did this for testing convenience, but now (I added this small feature in response to this question) it also automatically turns off the encryption+decryption part of the transport, since there's no point in wasting cycles doing encryption just to decrypt it a moment later so it can be written to disk unencrypted. Now jcp certainly doesn't aim to provide encrypted backups. That is a much bigger lift, and there are alot of specialized backup programs out there that do that already (e.g. plakar.io). Demonstration: *~/go/src/github.com/glycerine/jcp (master) $* *jcp source_from_here target_to_here* no ':' in src/target: starting local rsync server to receive files... (001)version.go [==============================] 100% 684.0 B 38.3 MB/s 00:00 ETA jcp.go:474 [pid 9073] 2025-03-29 09:20:47.705 -0500 CDT giver total file sizes: 43_651_011 jcp.go:475 [pid 9073] 2025-03-29 09:20:47.705 -0500 CDT bytes read = 53_715 ; bytes sent = 12_412_130 (out of 43_651_011). (28.4%) ratio: 3.5x speedup *~/go/src/github.com/glycerine/jcp (master) $* *jcp source_from_here target_to_here* no ':' in src/target: starting local rsync server to receive files... jcp.go:474 [pid 9300] 2025-03-29 09:21:18.856 -0500 CDT giver total file sizes: 43_649_411 jcp.go:475 [pid 9300] 2025-03-29 09:21:18.856 -0500 CDT bytes read = 693 ; bytes sent = 8_491 (out of 43_649_411). (0.0%) ratio: 5140.7x speedup *~/go/src/github.com/glycerine/jcp (master) $* On Saturday, March 29, 2025 at 12:28:05 PM UTC jeff.ko...@gmail.com wrote: > I read G's question as whether jcp can efficiently update incremental > backups from primary to secondary local storage, e.g. daily backup of a > home dir to an attached memory stick or an alternate folder on the same > filesystem. > > On Friday, March 28, 2025 at 3:55:30 PM UTC-7 Jason E. Aten wrote: > >> Yes? The question is a bit confusing. jcp copies from >> >> host1 filesystem -> over the network -> (jsrv running on) host2 >> filesystem, >> >> and while (for testing mostly) you can leave off the host: prefix on >> both giver and taker, to copy things from local disk >> over the TCP/UDP network stack, and back to the same host's local storage >> -- >> this is going to be wildly less efficient than using tar or cp to do >> local disk copies. >> >> On Friday, March 28, 2025 at 6:24:30 PM UTC G wrote: >> >> is it able to use a local storage as backup? >> Thanks >> >> On Thursday, March 20, 2025 at 10:04:45 PM UTC-7 Jason E. Aten wrote: >> >> I've open sourced jcp, my rsync-like file transfer library and CLI. >> >> By using Go's fabulous multicore support, jcp can do diff-only filesystem >> syncs >> up to 3x faster than rsync (which is a single threaded C program). >> It uses a parallelized version of the FastCDC algorithm with a >> Gear table to ship only the changes, even in binaries. >> >> https://github.com/glycerine/jcp >> >> From the README: >> >> This project (jcp) was written to harden and polish my RPC system, >> https://github.com/glycerine/rpc25519 , whose high-performance and novel >> Peer/Circuit/Fragment paradigm is featured here. In this evolution of RPC, >> peers communicate fragments of infinite data streams over any number of >> persistent circuits. Since the roles are peer-to-peer rather than >> client-server, any peer can run the code for any service (as here, in the >> jcp case, either end can give or take a stream of filesystem updates). >> >> Enjoy. >> - Jason >> >> -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/golang-nuts/065c83e4-6dc8-4c3a-9acc-120490ed191cn%40googlegroups.com.
