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Warning: Religious war ahead!




1. Why partition?



(MoonShadow's opinion follows; MoonShadow is an amateur, and is always willing to be taught by those better informed than himself - take what follows with a pinch of salt!)

Yes, there's nothing to stop one just lumping everything together in one huge partition. But it may be helpful to not do that. In particular, it may be helpful to put at least /usr and /home into their own partitions.

(a) To allow for growth


Why? Because they are both liable to grow lots. /home is where your data is stored. /usr is where software tends to get installed. Temporary data gets written to /tmp and /var by software that is running, and in most cases if the partition that /tmp and /var are on fills up, bits of the OS will begin to quietly fail. Typically, not very much room is required for temporary data; but it's a nonzero amount.

(b) Ease of migration


Putting the pieces of your filesystem that are going to expand a lot on separate partitions makes it easier to migrate to bigger partitions later should you decide to do so.
PeterTaylor isn't quite sure he agrees. Initially, he had all his stuff on the primary partition. When he finally worked out that the reason X had started breaking was that it had no space for /tmp, he spent most of a Saturday setting up the current structure. If you don't know how to use mount, learn _before_ you starting moving your partitions. (I started off trying to use symlinks... Fortunately, I had a Windows box which I could use to access the web and get help from a few people on the UserFriendly discussion board). If you do know how mount works, it's fairly straightforward to migrate everything.

(c) Flexibility of system recovery(?)


OK, "expand a lot" isn't really the reason. One might want to stick /usr and /home on separate partitions rather than /tmp and /var because it's a lot easier to get the system into a state where it is not using the former so you can remount them without rebooting than in a state where it is not using the latter. - MoonShadow

(d) Sharing /home between different root filesystems


Another reason is that if you want to install a different distro of Linux then you can easily mount the /home partition in the same place without any faff (though I think there's now a mount option to mount a subdirectory of a filesystem, so that may be less relevant). - Hawk

(e) Mitigating effects of full partition


As an additional reason to the ones listed above, it helps the novice user's system to not break in nonintuitive ways. Typically, if (e.g.) X is freaking out because you are out of space, there is no obvious indication that that is the reason - you have to examine the logs, and it might not necessarily be obvious even then. If you are copying a file and run out of space, you get told so and can go and fix it without burning time investigating the cause of the problem. While it is true that this is a problem with error reporting, the simplest way for the novice to deal with it is to partition such that the system is more likely to fail in an intuitive way than with intermittent glitching with no obvious cause. However, this is merely my opinion - YMMV. - MoonShadow

/var is something I've often been glad was in a partition to itself: occasionally something goes mad, or just gets used more than expected, and the resulting logs soon fill up whatever filesystem they happen to be in; and it's nice not to have home directories impacted by this.  Rjk

(f) Different selections of mount attributes or filesystem types


Also, splitting the filesystem up into partitions allows you to set some of them nosuid, noexec, readonly and so on as appropriate, thus improving security. - MoonShadow
noexec doesn't work properly and has zero security benefit.  Rjk
e.g. tmpfs for tmp, reiserfs for /home or whatever --Bobacus

(g) Reduce the effects of filesystem corruption


If /var's superblock is broken, at least you have /home (say). --Bobacus

(h) Ease/flexibility of imaging


More partitions means you can separate image files, to image a smaller portion. If the image files are smaller it is (obviously) less data to keep throwing around. This is probably not a concern for the average home user :-) --Bobacus

(i) Filesystem fragmentation or locality


There is a small benefit to having files close to each other on disk. (e.g. I read somewhere that someone had done an experiment, where a 20G partition on a 40G disk was marginally faster than a full 40G disk. But that was sacrificing space for speed...) --Bobacus

Fragments of individual files would be located close with a simple multiple partition setup. --Bobacus



2. Why not partition?



Why bother with separate partitions?  I can understand having /boot separate on machines where big disks are a problem.  Anything else just limits your flexibility IMNSHO - yes you might fill up the disk and the machine starts complaining a bit, but if you fill up the disk then you've got to start deleting stuff anyway.  If you've got more than one user then enforcing /DiskQuotas? is better than limiting them by the size of /home.  Novice users should certainly just stick to having one / and one /boot partition, because they don't know how the relative sizes of /usr /home and /var are going to work out. --Mjb67

Complicates Debian woody installation due to apt cache being located in /var (see below)

If you have a separate /tmp (I use tmpfs for this mostly since I don't care about the contents of /tmp surviving reboots, but you could just use disk), what (if any) is the argument for separating / and /usr?  Rjk

The most common argument I've seen is so that you can mount /usr read-only. Also, /usr/src tends to grow rapidly if you are rolling your own kernels. Admittedly, neither of those are very strong reasons. - MoonShadow
How many distributions actually make it practical to mount /usr RO?  I believe it's supposed to be an implication of Debian policy that it should work but I've no idea if it actually does, and bet that some package somewhere breaks it... Rjk
dpkg :-) --Bobacus (otherwise I've had no problelm with a read-only /usr)



3. Discussion



Rjk would say that there are two primary considerations to balance:
The decision of whether and how to partition depends on how you balance these considerations, and that depends on what you're trying to achieve.

Logical volume management is glorious, where supported.

Bobacus says: don't forget inode requirements! I spent ages wondering why my Maildir-format IMAP server was giving "No space on disk" errors when df clearly showed there were free blocks (and not just for root), thinking it was some kind of bug in the IMAP server. It was only when I got the same error trying to create a small file in my home directory that the penny dropped... df -i people. (For some reason /home had escaped my reiserfs fervour and was still on ext3.)

(more religious wars go here)



4. What to partition?



MoonShadow's recommendations for partition sizes:

/ 300-400Mb
/usr 1.5Gb-4Gb, depending on how much software you want to install to play with
/home 100-200Mb (unless you are planning to store media in your home directory,
in which case whatever you can afford)

If you're installing Debian, it downloads packages into /var, so that needs to be big enough during installation for whatever will end up in /usr! :/ evil.. sorry, Kazuhiko-san, I had no clue! - MoonShadow
*shrug*  Don't worry about it.  It's not a huge process to scrap it and start again.  I think one of my main problems with what I've seen of Linux so far is a complete lack of helpful recovery functions.  Shouldn't it either tell me/warn me that I should leave more room for the drive with /var in it or tell me a way around it when it fails?  As it is, I was dropped back to a command prompt without even being told a way of re-running the installer... - Kazuhiko

Don't forget the swap partition. Swap+RAM should total 200+ megabytes for a heavily-used workstation. You can add more swap partitions later if you start running low on memory.
PeterTaylor would say you want 256MB+ RAM and 256MB+ swap for any workstation on which you're running X. (Most certainly don't do what I did once and try running X with only 32MB physical mem).
MoonShadow disagrees. X with fvwm2 or twm is perfectly happy with 32Mb physical memory, and /Debian and /RedHat? distributions both include a set of twm-and-xsession-and-nothing-else configuration options. 1024x768 32-bit colour X running Gnome or KDE desktops on top of Enlightenment might be rather unhappy, but that's another matter. MoonShadow's main desktop has 140Mb or so of RAM (110 or so until very recently), runs 4 800x600 X servers with two users typically logged in and running mozilla and a few xterms all the time, and uses about 80-90Mb of RAM total running all that. Swap file gets used when third user logs in, or when someone starts up gimp or xine.
Ye gods and little fishies.  I know linux (and especially X) are becoming bloated - but are you serious?  I've seen it running on four meg 486s just peachy (some years ago) - so what on earth has gone wrong since then?  --Vitenka
To be fair, we *are* talking about packaged distributions here - the ones you can get going just using gui/menu tools, without touching a text editor, that contain lots of multimedia fluff. OTOH, you can get a two-floppy distribution that includes an X server and runs on a 386DX with 4Mb RAM out of the box... - MoonShadow
PeterTaylor was running a single 800 x 600 Gnome desktop and sitting for about 5 minutes opening an xterm while the HD churned. This was on a fairly standard RH7.2 install. I'm guessing 24 bit colour.
Like I said above, blame Gnome, not X (difference being the one is somewhat easier to run X applications without than the other) - MoonShadow
My apologies. I would note, however, that with RH, and possibly other distros as well, if you want to install X you have to have Gnome or KDE, and if you run xdm you will get a desktop.

Incorrect. Like I said above, both RH and Debian include an option on the xdm login screen to run xsession with twm - just click on the "sessions" tab. - MoonShadow
There is no tab. Just two text fields for username and password.
Lately KDE's been making people use 'kdm' not 'xdm', which doesn't have quite so obvious session options (although it is still possible to coerce a 'failsafe' session out of it if you poke it right).
If you have a fast and a slow hard drive, put /tmp, /var and the swap partitions on the fast one; /usr too if it'll fit. If you're tight for space, you can have some swap partitions on each drive and give them priorities.




5. Show and tell.




PeterTaylor


PeterTaylor's RH7.2 install gives this response to "df -m":
Filesystem           1M-blocks      Used Available Use% Mounted on
/dev/hda1                 1511       138      1297  10% /
/dev/hda2                 1010       112       846  12% /home
/dev/hda3                 1511      1307       128  92% /usr


Senji


For comparison, my laptop has (in the Debian/stable install):
Filesystem           1M-blocks      Used Available Use% Mounted on
/dev/hda5                  957       873        36  97% /
/dev/hda7                  357         1       338   1% /tmp
/dev/hda8                 1922      1678       146  92% /mnt/aleph
/dev/hda9                 1104       573       475  55% /mnt/bet

Where /mnt/aleph currently has most of usr and home, and /mnt/bet has those bits of usr with CivCTP in.  home uses up about 1/3 of /mnt/aleph. -- Senji

Emperor


Emperor's computer looks much like this:
Filesystem           1k-blocks      Used Available Use% Mounted on
/dev/hdb1              3844584    163892   3485396   5% /
/dev/hda1              1035660     50256    932796   6% /spare
/dev/hda3             57551060  57533780     17280 100% /mirror
/dev/hdb9              7088976   4073756   2655116  61% /home
/dev/hdb8              3844584   2643936   1005352  73% /extra
/dev/hdb7              3844584    564788   3084500  16% /var
/dev/hdb6              3844584   2743716    905572  76% /sound
/dev/hdb5              3844584   2791372    857916  77% /usr

...and yes, that mirror does need fixing :( OTOH, the routing table (minus all the secnet gumpf) is quite scary too:
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
172.16.22.200   172.16.22.65    255.255.255.252 UG    0      0        0 eth0
62.3.108.16     0.0.0.0         255.255.255.248 U     0      0        0 eth2
172.16.22.224   0.0.0.0         255.255.255.240 U     0      0        0 eth0
172.16.22.240   0.0.0.0         255.255.255.240 U     0      0        0 eth1
172.16.22.0     0.0.0.0         255.255.255.128 U     0      0        0 eth0
0.0.0.0         62.3.108.22     0.0.0.0         UG    0      0        0 eth2


I opted for sound files to be somewhere else; mostly so I can avoid backing them up :) There's a swap partition on hda (500MB, and I have 448MB RAM); I think 5GB for /usr as you suggested above is over-doing it a bit - I'm only using 2.8GB here, and I Have quite a lot of crufty software and data in /usr these days...

Mjb67


Oooh, since we're all doing it:
[mjb67@mjb67 mjb67]$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/hdb2              54G   31G   21G  59% /
/dev/hdb1              45M   17M   26M  40% /boot
/dev/hda1             9.5G  6.9G  2.6G  73% /mnt/cdrive
none                  252M     0  251M   0% /dev/shm 


So you see, I've just gone for one big partition, really.  28G of that 31G is anime in /home. /usr is 2.4G.  Heh, on the windows side /mnt/cdrive is called hda1 in Explorer :-)

Kazuhiko



My anime folder on my laptop comes to 6Gb already and I have some stuff on my home machine which is not on my laptop ^^;; - Kazuhiko

Tsunami


Filesystem           1M-blocks    Used      Available Use% Mounted on
/dev/hdb8            2950         2702      98        97%  /
/dev/hdb9            5907         351       5257      7%   /home
none                 378          0         378       0%   /dev/shm
/dev/hdb6            2032         6         2026      1%   /mnt/shared1
/dev/hde1            38162        37133     1030      98%  /mnt/ntfs/6
/dev/hda5            10237        6256      3982      62%  /mnt/ntfs/1
/dev/hda6            12928        11681     1248      91%  /mnt/ntfs/2
/dev/hdb5            2040         914       1126      45%  /mnt/ntfs/3
/dev/hdb7            5115         3086      2030      61%  /mnt/ntfs/4


It now looks like this, after mounting all my NTFS patitions ^_^

Read-only, I trust ^^; - MoonShadow

I will be changing hde1 so that it is mounted in ntfs/5 rather than 6, so there isn't a gap.

Hawk


Filesystem            Size  Used Avail Use% Mounted on
/dev/hda2              25G  6.9G   17G  30% /
/dev/hda1              19G  3.4G   16G  18% /win98
/dev/hda4              30G  6.1G   23G  22% /lfs

I had just one Linux partition for a while.  Then I got bored one day and installed /LinuxFromScratch?, in another partition.  However, now I've been a Linux user for a while I think if I was starting again I would make a number of smaller partitions.

Vitenka


Filesystem            Size  Used Avail Use% Mounted on
/dev/hda          201932.8   72M   26M  73% /
/dev/hdd                4G   18M    4G   1% /msdos


But the hard drive is failing (has failed) irrecoverably.
Seriously - I understand the arguments for having a separate main partition - but why have a separate home and usr?
(PeterTaylor) In my case, it was in part a hangover from my Windows system experience, where it makes a lot of sense to have separate partitions for OS, apps and data (because virus writers might forget to trash every filesystem). Since Linux has fewer virii and one root, this is less relevant, but I didn't spend ages thinking about reasons for and against partitioning when I installed RH.
Fair enough - but all the problems of separate partitions for windows still apply, surely - that it is annoying to have two partitions with not quite enough space left for your game, between them it would be fine, but you can't quite fit it in...  Symlinks help, but kinda annoying.  I understand state of the art allows you to munge a whole bunch of different drives onto a single mount point and not have to worry about what goes where - how easy is this to set up in practice?  --Vitenka
(PeterTaylor) I only use about 30% of each partition on the Windows box, so I'm not worried about leftovers. I have no experience in munging drives into a single mount.

MoonShadow


Not following my own advice; /usr isn't on a separate partition, although /usr/src ended up being..
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/hdb1              2029904   1467080    459708  77% /
/dev/hdc7            109084512  17466820  86076476  17% /home
/dev/hda1              2084324   1679320    405004  81% /mnt/c
/dev/hda6              4818072   3876900    941172  81% /mnt/e
/dev/hdc1               988212    295628    642384  32% /usr/src
/dev/hdc6              7882560    645544   6836600   9% /usr/share
/dev/hda3               790588    642380    108048  86% /mnt/oldhome


Rjk


lyonesse$ df -m -xnfs
Filesystem           1M-blocks      Used Available Use% Mounted on
/dev/hda3                 1867      1503       267  85% /
/dev/hda1                 2047      1747       300  86% /dos
/dev/hdc1                 7985      1487      6499  19% /dos2
/dev/hdc3                 4032      1750      2077  46% /export
/dev/hdc5                 1008       719       238  76% /var
/dev/hdc6                11569      2309      8672  22% /space
tmpfs                      256         1       255   1% /dev/shm

sfere$ df -m
Filesystem           1M-blocks      Used Available Use% Mounted on
/dev/hda3                 4806      1718      2844  38% /
/dev/hda1                   29         5        23  17% /boot
/dev/hda5                  277       218        44  84% /var
/dev/hda6                  185       141        34  81% /var/spool/news
/dev/hda7                  462       406        32  93% /var/spool/squid
/dev/hda8                 3845      3366       283  93% /export
/dev/hda9                16061      9904      5342  65% /space
/dev/hda10                2065      1896        65  97% /export/mp3
tmpfs                      256         1       255   1% /dev/shm

rollercoaster$ df -m -xnfs
Filesystem           1M-blocks      Used Available Use% Mounted on
/dev/hda3                 5768      5124       351  94% /
/dev/hda1                   61         7        51  11% /boot
/dev/hda5                 5768      1307      4168  24% /space


ColinT



Keep it simple I always say. I'd be in trouble if I hadn't.

[colin@gateway] colin $ df -h
Filesystem            Size Used Avail Use% Mounted on
/dev/hda3             5.9G 5.3G  282M 96% /
/dev/hda1              28M 8.5M   18M 33% /boot
//ping/mp3             83G 9.0G   74G 11% /mnt/mp3




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