No space to create more partitions, but there is free space
 

Hey guys. I rarely get to load a new server, so I was going through setting up my slices, first made /, then /boot, then swap as primary partitions, then when I went to make /home even though I had like 130GB free space, it said I didnt have space available.

Couple questions:
What am I most likely doing wrong that it's telling me there's no space? It's CentOS if that matters.
Primary partitions are just ones that could be bootable, so am I picking the right ones to mark as primary?

Well, probably the partition-table is full. Print out the list of partitions and be sure you didn't mess one up. Research "extended partitions."

Could there be some existing partition on the drive?

Not sure that is exactly true. Some things could change that would allow almost any number of os's to be booted to a single drive.

When I got to the partitioning screen, first thing I did was delete everything. Then I setup those 3 on the internal drives on the server, then it wouldn't let me do any more. But it did let me setup partitions on an external array after that, so must just be something with doing more on the internal drives.

Please post the output of on that server, run as root.

I run that while booted off the centos dvd?

Yes, this way we can see what exactly is the situation with your disks.

do you know how I do that from the CD? I've never done it before

If you're in the graphical installer, press ctrl-alt-F2 to switch to a VT with a shell prompt.

okay thanks. I will try it next time I get to the server and post what it says

Yeah... "and relax... no rocket-science here... it's only ones and zeros." ;) The partition-table is just "a table," located in the first sector of the drive and known to the controller hardware. It has a fixed number of entries, but (in the usual "we never thought we'd run out ... now what do we do?" Engineering Hack), the last entry can be a (tah, dahhh!) "extended partition" which can contain "more partitions." ("Whew! That was close!")

Once you boot the CD and run parted on the drive, it will tell you exactly what the partition-table now contains. From there, you can easily see your way to setting-up whatever you want.

Chances are you're hitting the 4-partition limit in the table. The partition table only allows 4 partitions in it, however one of those four can be an extended partition, which allows other partitions inside (odd, I know). If you're only going to have 3 partitions, you can make 3 primary and be fine. If you're going to have 4 or more partitions, you should set up 3 primary and 1 extended, with the rest of your partitions inside the extended.

You've only mentioned setting up 3 partitions and then encountering an error when attempting to set up the fourth. This shouldn't be a problem, but perhaps there's already a 4th hidden partition that you're not seeing in the GUI. That's why everyone here is asking to see the output of parted -l.

side question: now that I've done Alt+Ctrl+F2 to get to the shell prompt, how do I get back to the installer GUI?

OK, here's what I'm seeing when I do parted -l:

Under my /dev/sda, which is the RAID1 of the 148GB drives on the server where i'm trying to make all my slices. I'll list the number, size, type, file system, flags columns for each, figure the start & end isn't important for now
partition table: msdos
1, 524MB, primary, ext4, boot
2, 146GB, primary,*blank*,lvm

Then I have 4 volumes after that for my external RAIDs, all of which are the entire space, they have partition table:msdos with each using the full space as ext4 and primary for Type.

I don't think I need/want to use LVM, as these "system" partitions are going to be fixed sizes, but I can't say I'm totally up on the pros/cons of LVM either.

Thanks for all the help everyone, I'm REALLY trying to learn Linux, but I can't even get past setting up partitions apparently haha.

I should probably say what I'm trying to do as well. I want to have each of these be their own slice

/
/boot
swap
/home
/tmp
/opt
/usr
/var

That way if one fills up, it won't bring all them down. We've had /var fill up before I'm told :(

You can have either 4 primary partitions, or three primary and on one extended, with the extended partition divided up into as many logical partitions as you like.

As other have said, your description doesn't track with the actual limits, so there is something else there which you haven't described. Unless you post better detail on what is there, we can't give better detail on what to fix.

In Linux logical partitions can be bootable. There is no significant difference in behavior or capability between a primary partition and a logical partition. If you wanted, you could allocate the entire drive as one extended partition, with no primary partitions, then allocate all your partitions as logical partitions.

johnsfine, what kind of "better detail" do I need to post? If I know what would be helpful to post, I can post it.

So really it doesn't matter if I check or don't check the primary checkbox as I'm setting up each partition?

Here's a link to the picture showing the entire parted -l if that helps
parted -l

I don't see any relationship between what you described in the first post (Created / then /boot then swap but then could not create /home despite 130GB available space) vs. what you showed later (/boot and lvm filling the non raid drive)

I don't use LVM, so maybe someone else will tell you why you might want to use it and how to use it.

If you don't want to use LVM, then why did you not delete the LVM partition to make room for the partitions you want to create?

Also, you described the list of partitions you want, but you seem to have RAID and non RAID volumes. You didn't say what you want on RAID vs. what you want on non RAID.

Exactly, and therein lies the problem. What I described in the first post were my actions through the CentOS installer GUI when it gets to the disk partitioning stage. I'm assuming the parted -l is showing what came on the server by default from the manufactorer, which I don't want.

In the GUI the first thing I did was go through and highlight everything that was set up then hit the delete/remove button, so it then just leaves me with 4 areas of free space, my internal RAID1 and the 4 external RAID5's.

On the 4 external areas of space, i'm just going to use those as data volumes for file storage.

...
OK, now your posts make sense. The CentOS install GUI was getting your input to plan the partitioning changes. It doesn't actually make any of those partitioning changes until a later stage that you obviously never reached.

Possibly, that installer won't let you set up four primary partitions. The partition table structure allows that, but it is unusual enough that some GUI front end might not be designed to allow it.

If you start over and make most of your partitions logical rather than primary, there should be no problem. It doesn't matter which (if any) of the partitions are primary as long as you don't have more than three primary, and you keep all the logical partitions together (don't alternate logical and primary in your physical layout).

Many partitioning tools expect you to create an extended partition taking up the rest of the disk (outside of the primary partitions) before you create logical partitions. Other tools just expect you to request logical partitions and they automatically create the extended partition to wrap around the logical partitions. I think the Centos installer is the second kind (creates the extended for you when you ask for logical) but I'm not sure. I haven't used a Centos installer in a long time and when I did use it, I pre partitioned the drives with different tool, so I didn't use the part you need help with.

When I click the Create button on the free space for the RAID1, it doesn't give me many choices, seem like I have to pick from either a standard partition (which then lets me mark as primary or not) or to make an LVM thing. I just keep picking the first option for a standard partition.

Now I just wish I knew how to get back to the GUI installer, I hit Alt+Ctrl+F2 to get to the shell prompt, but I don't know how to get back to the GUI haha.

I think Alt-Ctrl-F2 switched virtual terminals and left the GUI one running.

A different Atl-Ctrl-F should switch you back, probably F8 or F9. I'm not at all sure which, but it isn't hard to try each of them.

OK, i'll give it a shot, didn't want to mess up anything. Although, guess I don't really have anything to mess up as of yet haha. Just wish I could figure out what I'm doing wrong trying to partition my drives up.

So have you tried standard and then not primary (which would mean "logical" but might not say it)?

Just tried it and if I don't mark any as a primary partition I can make all the ones I want. it made the first 3 regular then the rest under an extended. although I don't really understand why

but now when I go to make my partitions on the four external arrays it tells me not enough free space on disks. I'm not checking the primary partition box either

Below is a pic of the screen I uploaded, showing what it let me setup. Now when I go to setup a drive on sdb using the entire space, it gives me the same error it did that led to my original post. and I made sure to only check sdb when saying which drives to use. or do i need to force the ones on the arrays to be primary (for some reason I dont know)?

http://tinypic.com/r/20aqn90/6

Each of those four external arrays already has a partition apparently filling the array.

What do you want there?

I expect you want the four partitions you already have, so you just want to specify mount points for those partitions, rather than create new partitions. If you want to create new partitions, you need to delete the ones you have.

Also, all of that may be easier to do after Centos is installed. You need to let the installer know where /boot and / and /home etc. are (any directory the installer needs to write to). But other mount points (such as the /data0 you already set up) can be done in the installer or done later, whichever you find more convenient.

you are absolutely right. I deleted and recreated the rest of those. everything is okay now. forgot I already made those ext4. I'm still confused on the primary ones, like why i should our should not need them, like the pros vs cons

Primary vs. Logical makes no significant difference in Linux. What the GUI installer did with your selections for the first hard drive is fine.

OK, thanks. So if it makes no difference, why is there still a choice? backwards compatibility of some kind?

Guess I'm still not not understanding how/when you should use primary vs. non-primary, and doing some reading looks like you can/should mark one partition as "active" somehow too?

The basic thing is that only four primary partitions are allowed. One of these can be an Extended partition in which multiple logical partitions may be created. You can google to get more detailed info on the history of primary/extended/logical partitioning if you are interested.As far as the necessity, as indicated above it doesn't matter whether you use a primary or logical partition for Linux. AFAIK, you still need at least the boot files on a primary partition for a windows system to boot. A windows system AFAIK still needs to be have an active/bootable partition marked and this is not necessary for Linux

OK. I guess I won't worry about it then. Thanks to everyone for your help on this, I'm going to mark it as closed.

"active" is also a non Linux (at least non Grub) concept.

I'm pretty sure Centos still uses some form of the Grub boot loader and very sure it still uses some boot loader that doesn't care about primary vs. logical and doesn't care about active.

A Windows boot loader needs to load part of itself from a primary partition. Windows compatible MBR code loads that part of the boot loader from the "active" primary partition. Windows then expects that its boot code was loaded from the active partition. Various multi-boot systems (including Grub) have ways of patching which partition is "active" at boot time in case you have more than one version of Windows or other non Linux OS that cares about "active". But all that only matters if you are multi-booting multiple OS's and some of them are not Linux (it only is complicated enough to need your attention when more than one of the OS's is non Linux).

Linux doesn't care about any of that.

But sometimes the hardware does. My laptop (Linux only) refuses to boot if there is not one partition with the boot-flag. It doesn't matter at all which partition is marked, but the flag has to be there.