there is a tool called ionice that comes with the util-linux package,
which should help other read/write processes if you are multitasking.
ionice shouldn't slow down rdiff-backup if there are no other io
processes going on.
On Thu, 13 May 2021 at 03:08, Eric L. Zolf <ewl+rdiffbac...@lavar.de> wrote:
>
> Hi,
>
> first, I don't see anything surprising in what you describe, so all
> normal AFAICJ.
>
> Second, rdiff-backup needs to check each source file/directory and each
> target, compare them and then copy (or not), so if you have some 2300
> files to backup, that would sound about right. If the target or the
> source file doesn't exist, it would give an error.
>
> If the files are small or don't have changes, the lstat happen a lot and
> nothing much else; this is typical random access. It gives a much
> different access pattern than the copying of bigger files, where more
> sequential is typically done to read/write the file's data.
>
> There is no real way to improve the situation, rdiff-backup goes as fast
> as it can and I personally don't know an I/O-equivalent of "nice" (and
> if you limit the I/O, the backup will be even slower).
>
> You could try the --no-fsync option to improve speed:
>
> --fsync, --no-fsync [opt] do (or not) often sync the file system
> (_not_ doing it is faster but can be dangerous)
>
> And, yes, the `rdiff-backup-data/increments` directory is used by
> rdiff-backup to keep track of file and directory changes.
>
> Hope this helps,
> Eric
>
> On 12/05/2021 07:10, Andrei Enshin via Any discussion of rdiff-backup wrote:
> >
> > Hi rdiff-backup folks,
> >
> > Since recent, during backing up I can see spike in IOPS up to 500 which
> > exhaust limit of a VM. Therefore backup process takes very long. I've
> > straced a bit and what I can see is: many failed lstat() syscalls:
> > % time seconds usecs/call calls errors syscall
> > ------ ----------- ----------- --------- --------- ----------------
> > 42.71 0.040247 9 4608 1420 lstat
> > 35.41 0.033370 12 2860 getdents
> > 9.41 0.008865 6 1431 open
> > 4.63 0.004363 3 1430 close
> > 4.03 0.003797 3 1431 fstat
> > 3.75 0.003536 2 1417 getuid
> > 0.04 0.000039 39 1 unlink
> > 0.01 0.000013 1 9 read
> > ------ ----------- ----------- --------- --------- ----------------
> > 100.00 0.094230 13187 1420 total
> > Seems rdiff-backup checks existence of some file/dir:
> > 10:13:16 lstat("/some/path/rdiff-backup-data/increments/foo/bar",
> > 0x7ffd832fa810) = -1 ENOENT (No such file or directory) <0.000020>
> > After backup is done, there is still no such file.
> > Seems the part in path - /rdiff-backup-data/increments/ - is some "config"
> > for rdiff-backup and probably it tryies to find something but can't?
> >
> > What might be wrong in my setup? What would you recommend to check to solve
> > the issue if it is issue at all?
> >
> > ---
> > Best Regards,
> > Andrei Enshin
> >
>
