Hi Ted, On 01.08.19 18:31, Ted Toal wrote: > There is a BackupPC config parameter named RsyncFullArgsExtra, but none named > RsyncIncrArgsExtra (to provide extra rsync args for an incremental backup). > I’d like to see such a parameter. My immediate use is that I’d like to > restrict rsync bandwidth to different amounts depending on whether it is a > full or incremental backup.
assuming that you want to use --bwlimit, can't you just add --bwlimit=<IncrementalLimit> in RsyncArgs, and an additional --bwlimit=<FullLimit> in RsyncFullArgsExtra? According to my tests, the second will override the first for the full limits. Slightly unelegant workaround, but effective. Note that the arguments are appended in the order RsyncArgs RsyncFullArgsExtra RsyncArgsExtra (see lib/BackupPC/Xfer/Rsync.pm, lines 307-334 or so), so you have to add the "default" (incremental) limit to RsyncArgs, not RsyncArgsExtra. Apart from that, are you sure that a bandwidth limit actually is what you're after? The (network) *bandwidth* used for incrementals and fulls does not differ a lot; it's the *I/O load* on the client that makes the real difference: IIUC, no matter what backup type, rsync needs to compare all file paths and some metadata. For incrementals, by default it compares path size modification-time; for fulls (with --checksum), it skips the latter two and compares path checksum instead. For the computation of the checksums, the client will read each file in its entirety. That makes for a lot of *I/O bandwidth* on the client. But regarding the *network bandwidth*: The checksum is an MD5 hash, i.e., 128 bit = 16 bytes long. Without digging in the source, size and modtime are probably integers of 4 or 8 bytes each. So my guess is that the bandwidth difference is *at most* 8 bytes per file, but more likely 0... HTH, Alex
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