SEO

Okay peeps, looks like I'm finally going to get around it: for over a month
now I've been waiting on installing Gentoo on my brandnew "are you sure
this isn't a mainframe?" box because of the delayed release of kernel
2.6.24, and now it's finally here. :-)

So, before I begin, allow me to explain what this machine is built of and
how I intend to go about it...

First of all, these are the hardware specs (including some non-OS related
ones )...
- Tyan Thunder n6650W (S2915) motherboard (twin-socket ccNUMA)
- 2x AMD Opteron 2218 HE (2.6 GHz, 68 Watt, dualcore)
- 32 GB ECC registered DDR-2 pc5300 (667 MHz, brand ATP, 8x 4 GB modules)
- Adaptec 31205 8-lane 12-channel PCIe SAS RAID controller
- 4x Hitachi 147 GB 15k SAS disks
- Plextor PX810-SA double layer SATA DVD writer
- Asus GeForce 8800 GTS 640 MB PCIe videocard
- GeCube Radeon 9250 256 MB PCI videocard
- Zippy 800 Watt EPS12V power supply
- CoolerMaster CM Stacker 832 chassis
- Iomega REV 70 GB (140 GB compressed) USB removable storage

As I explained once before in another post, the machine will be set up with
Xen - preferably version 3.1.x - and at least three but possibly four
virtual machines, each of which will be running Gentoo.

The first unprivileged virtual machine will be used as a workstation and
will have most of the RAM available. Then there is of course the first
virtual machine, which is the privileged one, and then as I said, one or
two other unprivileged virtual machines in a dedicated server role.

The machine will be connected via USB to a Brother MFC 9880 multifunctional
device that I got for free. The device has a built-in fax but I'm on cable
so I can't use that. I will however use it as a scanner, printer and
copier.

There are two SGI 21" CRT monitors, both of which are connected to the
GeForce adapter, and one of them is also connected to the Radeon adapter.
I use this set-up so that I would have visual output via the Radeon during
the system's main boot and shutdown, with the GeForce hidden from /dom0./
In /domU,/ the GeForce will only be visible to the workstation
installation, from which in turn the Radeon will be hidden.

Because of a limitation of the SCSI protocol that allows systems with a
legacy BIOS (and thus the traditional "maximum four primary partitions") to
only have 15 partitions and my wish to use distinct filesystems for the
traditionally relocatable UNIX directories, I will be using LVM2 for just
about everything, except for the main */boot,* / and swap.

In addition, I intend to mount several filesystems read-only during normal
operation in all virtual machines, including - and this is something I've
never done before - the root filesystems. The respective */root* - home of
the superuser - will of course be split off from the root filesystems as
well, and */tmp* will be a /tmpfs/ in all virtual machines, as will
*/var/tmp/portage* be in the /dom0/ virtual machine.

Now, one of the advantages of using logical volumes (if not the main one) is
that this gives you flexibility in terms of diskspace. However, I still
would like to dedicate only as much as needed (and a bit extra) to each
filesystem, just for consistency. I don't wish to radically overallocate
diskspace from the start, nor do I want to be short of diskspace, forcing
me to extend the logical volumes right away. It's a brandnew system, so it
needs a clean install. ;-)

Thus, I turn to you, the longstanding Gentoo gurus <cough> (), with a
couple of questions...:

(1) How much diskspace would I need to allocate for...
- /usr
- /usr/src
- /usr/portage
- /usr/local
- /srv
- /opt
... in a basic server installation and in a basic workstation
installation? (I will be using the XFS filesystem for all slices
and the machine is hooked up to two UPSes.)

The intended usage is as follows: the workstation install will have KDE 3.x
with either Beryl or Compiz Fusion - depending on which one is in Portage
as marked "stable" - with KDE window decorations, office software,
scientific, development and graphical software - for stills, no streaming
video - while the servers will be the /dom0/ virtual machine, an IRCd
machine and possibly an Apache and mailserver machine respectively - I
haven't decided on the e-mail server yet, both in terms of whether I will
set one up and in terms of which one to use.

My second question is not really Gentoo-specific, but since I couldn't find
the information elsewhere I thought I'd ask here, just in the event that
one of you knows the answer...:

(2) As of 2.6.23, the Linux kernel includes Xen support, but is
this only for unprivileged guests or for privileged guests as
well? In other words, will I still need to patch the kernel
tree?

Advice, comments, plush penguins and flames are highly welcome, although
preferably less of the latter...

--
Aragorn
(registered GNU/Linux user #223157)

Aragorn wrote:

> Thus, I turn to you, the longstanding Gentoo gurus <cough> (), with a
> couple of questions...:
>
> (1) How much diskspace would I need to allocate for...

This is alwyas a bit tricky to answer, as much depends on what you will be
installing.



> - /usr
3-4G should be enough, but if you would bloat with Gnome2, I think you need to
add a gig or two more.

> - /usr/src
A normal kernel source + compiled objects and kernel will take around
290-400M, just multiply with the number of kernels you will be keeping.
Myself I have set the portage build directory to resident inside /usr/src too,
mine is a bit bloated in size, 5G, but some packages like OpenOffice needs
quite a lot of space to be built.

> - /usr/portage
Today portage is 3.7G, but that will grow with the number of new packages that
will be included in future and shrink depending on which packages are dropped.

> - /usr/local
1M, really I have 164K worth of files in this directory and it's on an
installation that is soon 4 years old.

> - /srv
0M

> - /opt
This depends much on what pre-compiled packages you emerge, I have a number of
different JDKs installed, Acrobat, nero, staroffice, realplayer, skype and it
uses 1.2G.

For me the main difference on the server and the desktops are X11, and some
3rd party pre-compiled files, I may not need all of the files, but sometimes I
need to do some work remotely and then it's easy to have all my needed tools
on the server and at the same time it's good to have a lot of the server stuff
on the desktops, so you can experiment in a test environment before using it
on the server.


> (2) As of 2.6.23, the Linux kernel includes Xen support, but is
> this only for unprivileged guests or for privileged guests as
> well? In other words, will I still need to patch the kernel
> tree?

Can't say I can find Xen in the kernel source, KVM has been included for a
while. There is a Xen patched kernel included in Gentoo, but that is version
2.6.20, while those pre-compiled ones at Xen Community are built on 2.6.18.
Looking at kernel.org, I can't see anything mentioning that Xen would have
been merged.


--

//Aho

J.O. Aho wrote:

> Arthur Hagen wrote:
>
>> You can probably get away with less than 1 GB if you zealously clean out
>> /usr/portage/distfiles between compiles. If rebuilding world, you can
>> create a batch job like:
>>
>> emerge --color n -pe world | grep ebuild \
>> | sed -e 's/.*] /emerge -1 =/' -e 's/$/;rm \/usr\/portage\/distfiles\/*/'
>> | \ sh
>
> or emerge tmpwatch and set it to clean out the directory.

Ah, good old /tmpwatch.../ I had already forgotten about that one... :-)

--
Aragorn
(registered GNU/Linux user #223157)

Aragorn wrote:

> Well, I guess I should have said that I would be using the /srvdir/ USE
> flag, which most people won't use as it's rather exotic. If I understand
> correctly, then with /srvdir,/ many applications that normally install
> themselves in */var* would put their files in */srv.*

Um, I have no such flag on my system. Where did you learn about it?

# grep srv /usr/portage/profiles/use.*
/usr/portage/profiles/use.local.desc:net-im/gajim:srv - SRV capabilities
/usr/portage/profiles/use.local.desc:net-irc/srvx:bahamut - Choose bahamut
protocol over p10 protocol

pk wrote:

> Aragorn wrote:
>
>> Well, I guess I should have said that I would be using the /srvdir/ USE
>> flag, which most people won't use as it's rather exotic. If I understand
>> correctly, then with /srvdir,/ many applications that normally install
>> themselves in */var* would put their files in */srv.*
>
> Um, I have no such flag on my system. Where did you learn about it?
>
> # grep srv /usr/portage/profiles/use.*
> /usr/portage/profiles/use.local.desc:net-im/gajim:srv - SRV capabilities
> /usr/portage/profiles/use.local.desc:net-irc/srvx:bahamut - Choose bahamut
> protocol over p10 protocol

It was proposed to become a USE flag already over two years ago, considering
that */srv* is part of the FHS and is already being created - albeit left
empty - in most modern distributions.

There was some debate about it on the Gentoo forums as well, and so I
naturally presumed that this USE flag had in the meantime already been
adopted...

--
Aragorn
(registered GNU/Linux user #223157)

Aragorn wrote:

> It was proposed to become a USE flag already over two years ago,
> considering that */srv* is part of the FHS and is already being created -
> albeit left empty - in most modern distributions.
>
> There was some debate about it on the Gentoo forums as well, and so I
> naturally presumed that this USE flag had in the meantime already been
> adopted...

Yeah, now that you told I did some searches and found that GLEP 20 (the one
proposing the srvdir USE flag) is currently "approved but not implemented"

http://www.gentoo.org/proj/en/glep

And, reading b.g.o., it seems that it was indeed used for some time, at
least for some packages (apache and mysql, for example), but has been
removed since.

http://bugs.gentoo.org/show_bug.cgi?id=142235

On Fri, 25 Jan 2008 19:48:00 +0100, I waved a wand and this message
magically appears in front of J.O. Aho:

> Yeah, when you say so, I got the whole distfiles included in that
> size and it's quite a lot of files, as it's shared over NFS and it
> tends to be that a package which is stable for one architecture is
> unstable for others, so I have many versions of the source. My
> distfiles is 2.8G, which would imply that the portage is 0.9G large.

Mine's 9.8G in size, perhaps I should do some pruning )
--
http://www.munted.org.uk

Fearsome grindings.

Aragorn wrote:

> (1) How much diskspace would I need to allocate for...

I did this once when I first set up Gentoo, splitting up everything. Man,
oh man, what a pain. I seriously underestimated how much space is required
outside of /home.

Then I later bought a second disk (first one being 200GB, new one at 500GB),
put swap, /boot, and / on the first disk (swap at 8GB, /boot as 40MB
[complete overkill], and / as the rest), and /home on the second disk.
Just soooo much easier that way. Now I'm using ~40GB in /, and 254GB
in /home (and 133GB on an external disk that I only use for 'offline'
storage - stuff I don't need often). Really simple.

So, personally, I'd be inclined to set up similarly again. Set up a
20-40MB /boot partition (I only keep 3 kernels around, and it's using 10MB,
so you can figure out how much room you want). Set up your swap. Set up
your read-only / with about 15GB of space (which should be excessive). And
the rest goes in /home (which is probably your most dynamic read-write
space anyway). Then create /home/root, and bind-mount any other read-write
directories under there, e.g., /usr/src would be a bind-mount
to /home/root/usr/src, etc.

> - /usr
> - /usr/src
> - /usr/portage
> - /usr/local
> - /srv
> - /opt
> ... in a basic server installation and in a basic workstation
> installation? *(I will be using the XFS filesystem for all slices
> and the machine is hooked up to two UPSes.)

Darin McBride wrote:

> Aragorn wrote:
>
>> (1) How much diskspace would I need to allocate for...
>
> I did this once when I first set up Gentoo, splitting up everything. Man,
> oh man, what a pain. I seriously underestimated how much space is
> required outside of /home.
>
> Then I later bought a second disk (first one being 200GB, new one at
> 500GB), put swap, /boot, and / on the first disk (swap at 8GB, /boot as
> 40MB [complete overkill], and / as the rest), and /home on the second
> disk.

A swap partition the size of 8 GB would indeed be overkill, as the maximum
usable size for a single swap partition on /x86/ is about 2 GB. It is
however possible to use multiple swap partitions that size, but to make any
of them larger than 2 GB would be a waste of diskspace. ;-)

As for */boot,* I typically allocate about 75 to 100 MB for it, and I have
it mounted read-only during normal system operation, just as I do */usr,*
*/usr/local* and */opt.* I also use the /nodev/ mount option on anything
but the root filesystem, and /noexec/ and /nosuid/ for */boot* and */tmp.*

I normally also set /noatime/ for most filesystems, although I believe that
doesn't play well with the /tmpwatch/ utility. In fact, I normally specify
each possible individual mount option for every record in */etc/fstab,*
which makes it a lot easier to modify one afterwards. ;-)

> Just soooo much easier that way. Now I'm using ~40GB in /, and 254GB
> in /home (and 133GB on an external disk that I only use for 'offline'
> storage - stuff I don't need often). Really simple.

Well, it is my belief - and not mine only - that one should keep the root
directory as small and static as possible - I normally reserve some 250 MB
for / and that's already huge :-) - and thus I split off everything I can.
This helps spread the risk of filesystem damage en fragmentation - not that
fragmentation is necessarily a problem in GNU/Linux - and it allows you to
have certain filesystems mounted read-only, which is not only an additional
security feature versus any problems originating between the keyboard and
the chair, but also against malicious activity by another user. ;-)

> So, personally, I'd be inclined to set up similarly again. Set up a
> 20-40MB /boot partition (I only keep 3 kernels around, and it's using
> 10MB, so you can figure out how much room you want). Set up your swap.
> Set up your read-only / with about 15GB of space (which should be
> excessive).

Excessive indeed! if */root* is split off from the root filesystem, then
200 MB should still be far more than enough. ;-)

> And the rest goes in /home (which is probably your most dynamic read-write
> space anyway).

*/home,* */tmp* and */var,* with */root* being written to mainly by
the /bash/ command history. ;-) I recommend a /tmpfs/ for */tmp,* and
considering the huge amount of RAM in my new machine, I'll be using one for
*/var/tmp/portage* as well.

> Then create /home/root, and bind-mount any other read-write directories
> under there, e.g., /usr/src would be a bind-mount
> to /home/root/usr/src, etc.

I'm afraid I don't quite follow the logic of such a set-up... :-/

P.S.: Just in case I have given off the wrong impression, I'm not quite a
novice to GNU/Linux. In fact, I have only used Windows on one of my own
machines once, and that was Windows NT 4.0, which I have used for little
over two years on a Pentium II with 128 MB.

This was in a time when everyone else was using Windows 95/98, and thus
support for NT from hardware vendors was very weak, not to mention that NT
was not compatible with a lot of existing Windows software back then.

I chose Windows NT as a compromise solution as I was going to buy me a new
computer - i.e. the Pentium II - and I did not want to have to use an
MS-DOS-based operating system on such a powerful machine, especially not as
I had been working with the fully natively 32-bit OS/2 for five years
before that. My goal was originally to have a UNIX system on that machine,
but it was 1997, I didn't have internet yet at home - cable internet was
not even available yet in my town - and so to me GNU/Linux was still
largely unknown, while proprietary UNIX systems - I had my mind set on
NeXtSTeP for /x86/ - was incredibly expensive for non-corporate use.

I learned and discovered more about GNU/Linux throughout those two years,
and late 1999 I bought the Linux-Mandrake 6.0 PowerPack Edition at a
software shop while picking up Encarta as a Christmas present for my
brother and I installed it alongside my NT without any problems. Back
then, I still did not use my computer every day - I was still without
internet anyway - but I found myself more drawn to GNU/Linux than to NT.

Eventually, on January 1st 2000, NT refused to boot despite the Y2K updates
and the most recent Service Packs, and so my choice was easily made. I've
been using GNU/Linux ever since - mainly Mandrake (now called Mandriva) on
my own systems, although I've also installed systems with CentOS and played
around on some that had Slackware and Debian.

If I ever use Windows again, then it's on someone else's machine, and then I
don't feel comfortable - it never was what I really wanted, as I had
already hoped for a UNIX while I was still using OS/2. Windows seems
illogical to me and in many ways also obscure. I do however read up on
various operating systems and most of my friends use Windows, so I'm
somewhat aware of the Windows-specific problems they have, and of how and
why Windows has just got to be the worst possible operating system, both in
design and in code quality. ;-)

Still, regardless of the misunderstanding, I appreciate your post and your
willingness to offer assistance and experience. Much obliged! ;-)

After not having been active on Usenet for a long time, it's nice to come
back and see that it still stands tall as a medium for sharing knowledge
and for cooperating on projects, despite the attempts of trolls, spammers
and lunatics/netcooks at sickening it. ;-)

--
Aragorn
(registered GNU/Linux user #223157)

Aragorn wrote:
> Darin McBride wrote:


> (swap at 8GB, /boot as
>> 40MB [complete overkill], and / as the rest), and /home on the second
>> disk.
> A swap partition the size of 8 GB would indeed be overkill, as the maximum
> usable size for a single swap partition on /x86/ is about 2 GB. It is
> however possible to use multiple swap partitions that size, but to make any
> of them larger than 2 GB would be a waste of diskspace. ;-)

I still use the old rule of swap = 2.5*Ram, at work it has been a life saver,
as the desktop there has a quite limited amount of ram.


> As for */boot,* I typically allocate about 75 to 100 MB for it, and I have
> it mounted read-only during normal system operation,

I don't mount /boot at all, during normal operation there ain't any use of it
at all.


--

//Aho