Comment # 7 on bug 911347 from Thomas Blume

(In reply to Bruno Pesavento from comment #6)
> (In reply to Thomas Blume from comment #5)
> > I guess we'd need an absolute lower limit for small systems and an relative
> > upper limit for big systems.
> 
> Maybe there is a simpler solution. What really hurts slow disks is max file
> size.
> So something like "SystemMaxUse=400M" (or 1% of 40GB) and
> "SystemMaxFileSize=26M" (or three 8.4 MB log chunks as seen on my 64bit
> systems) is likely to make everybody happy. Anyway that sounds more
> reasonable than the current 4GB and 480MB, respectively, with the suggested
> 40 GB root/.
> If anybody really needs more, or less, he/she is not an "average" user IMHO
> and should know how to tweak system defaults.
> I'll try that on my slow test disk and report back anything of interest.

Thanks, would be good if you could test this.
Btw. the code includes some general limits on the journal size:

-->--
/* This is the minimum journal file size */
#define JOURNAL_FILE_SIZE_MIN (4ULL*1024ULL*1024ULL)           /* 4 MiB */

/* These are the lower and upper bounds if we deduce the max_use value
 * from the file system size */
#define DEFAULT_MAX_USE_LOWER (1ULL*1024ULL*1024ULL)           /* 1 MiB */
#define DEFAULT_MAX_USE_UPPER (4ULL*1024ULL*1024ULL*1024ULL)   /* 4 GiB */

/* This is the upper bound if we deduce max_size from max_use */
#define DEFAULT_MAX_SIZE_UPPER (128ULL*1024ULL*1024ULL)        /* 128 MiB */
--<--

but it seems they are too generous for old machines.