Patrick Chiang wrote:
> Almost all people will suggest me to turn off those unnecessnary
> services after installation, but what kind of services should be
> considered as "uncessnary"?
Good question.
Note: excess services can be a problem if they take up CPU time, memory,
or (even these days) hard disk space. There can also be security
considerations if they provide services to the network or to
unprivileged local accounts.
> 1.acpid,apmd
> Power Management Service.
> If this computer is a desktop = turn off (assume we have a UPS)
> if this is a laptop, keep it
> 2.cpuspeed
> Adjust CPU speed, those PC with speed-adjustable CPUs should have it.
> (Usually installed on a laptop?)
Sounds good.
> 3.dc_client, dc_Server
> Should be turned on if PC is one of multiple web servers with SSL
Hey, I don't even have it installed. (That's worth remembering, too: not
having a service installed means it has to be added back before it can
be a problem).
> 4.Irqbalance
> Should be enabled if you have multiple processors.
> 5.mdmonitor,mdmpd
> Should be turned on if you have a software disk array.
> 6.messagebus
> if this pc had installed KDE/GNOME...
Um. More and more stuff is using messagebus, and it's not always obvious
what is using it. I understand that a lot of hotplug uses the D-Bus
message bus.
> 7.microcode_ctl
> if your processor is pentium-class and higher(Pentium 60-200 is not
> included). AMD,Cyrix,VIA and those 64-bit processors are not included
> either)
And if you've got microcode to update. In most cases, this is better
done by the BIOS.
> 8.netplugd
> if you don't like your FC2 configure your network automatically after
> network is restored, you can have this service disabled.
> 9.random
> Used to generate random numbers...leave it alone?
Not really a service: look at the script. It doesn't provide any service
to anything on the machine or off, except the kernel. And it doesn't
generate random numbers.
(In order to provide really high-quality random numbers, real randomness
is prized and preserved by the kernel. Some computers have a hardware
random number generator: others rely on "entropy" from the precise
movements of mouse, the precise length between keystrokes, and the
minute flutters of a hard disk, among other things.
> A.rawdevices
> Used for SCSI or some special purpose application, like Datbase Server?
> Don't know :(
Certain high-end database servers work better if they can store data
directly on the "raw" device, without going through the filesystem. This
was more true ten years ago: filesystems have got better, and some
high-end databases are at least as happy working with files.
Often, DBA lore will say that "raw devices are faster", so an OS (or
a database) has to support raw devices as a "check-box feature", even
though there is no advantage in benchmarks...
> B.readahead, readahead_early
> Those two services can help FC2 improve its performance by load some
> program in advance.
> C.services?
> Don't know whtat this means...
"An internal xinetd service, listing active services."
(/etc/xinetd.d/services)
I've got this one off, but I doubt it makes much difference.
> D.sgi_fam
> SGI's File alteration monitor
> Help some applications to notify user or other programs about the
> changes.Maybe disabled if your pc is a text_based server???
See my comments on messagebus, although I don't think hotplug relies on
it...
There was talk of a future Samba using a derivative of fam, and the cone
e-mail client seems to need it.
Any other comments?
James.
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