[Samba] Question about Sizing of Samba Linux Server

J Martin Rushton martinsworkmachine at gmail.com
Tue Feb 5 14:40:16 UTC 2019

Memory taken up by the buffer cache is available for use.  On a Linux
system writes to disk occur asynchronously, th e process first moves the
data into system buffers, then continues with what it was doing.  At a
later time the operating system moves the data from memory to disk, but
does not immediately blank the page.  Pages which are left as a copy of
disk are therefore a cache, but can be released if another process
requires them.  Indeed, they are _only_ released when required, so that
over time all memory pages end up being used, or dwelling in the buffer
cache.  Cached pages are recovered very quickly with a soft page fault,
going to disk requires a hard page fault which is dealt with a disk speeds.

Be aware that the foregoing only applies to single node machines
(including those servering the network via NFS of Samba).  In a true
cluster environment with a SAN, the on-disk version may be updated by
another node, so the cluster-wide filesystem needs to invalidate the
cache, but that is a whole new level of complexity.

The short answer therefore is that "my RAM is all eated up in the
buffer/cache" is indeed normal.  In general, more RAM is nearly always
better, but if "users are not complaining" you may have difficulty
getting past management!



On 05/02/2019 13:20, Geoffrey MEZERETTE via samba wrote:
> Hello all,
> I'm jumping into this mailing list because my question still unsolved after
> Googling the web.
> Do you know any performance of sizing recommendations about Samba 4.7.1 ?
> For few informations :
> 2vCPUs / 1 Core
> 8Go of RAM
> 140 simultaneous Windows users / 250 at most
> 20 NFS shares mounted via fstab
> This question because my RAM is all eated up in the buffer/cache (normal
> according to last chapter of :
> https://wiki.samba.org/index.php/Performance_Tuning).
> Users are not complaining but I don't know if the servers is needing more
> or less.
> Any advice will be greatly appreciated, thanks.
> *Geoffrey MEZERETTE* • Ingénieur Systèmes et Réseaux • Enovea •
> 16, rue Jacques Monod • 76130 Mont Saint Aignan • Standard +33 (0) 2 32 18
> 82 66 • geoffrey.mezerette at enovea.net> www.enovea.net <http://www.enovea.net/>• <http://www.enovea.net/>

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