setup cannot find swap space

Skaperen · 03-05-2011, 06:52 PM

While installing slackware64-current, setup cannot find swap space. This is an extreme case pushing limits with a huge GPT partition table. So there is probably some limit on the number of partitions, or partition number, the swap search looks for. Of 41 partitions I made scattered around the number range from 1 to 128, the swap space exists as partition 90. Maybe the problem is it can only check partitions 1-15 because 16 and beyond have to use a different device major number? When I do proceed with the install, /dev/sda90 is listed as a choice.

FYI, so many partitions is planning ahead for a multi-boot system.

The rest of the install went OK.

Skaperen · 03-05-2011, 07:06 PM

Here's the layout after the install completed. I have not added the swap space to /etc/fstab, yet, but it does work OK when I manually do "swapon /dev/sda90".

Code:

bash-4.1# parted /dev/sda u s p
Model: ATA WDC WD10EADS-22M (scsi)
Disk /dev/sda: 1953525168s
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start        End          Size         File system     Name                Flags
100     34s          2047s        2014s                        Linux Reserved
 1      2048s        524287s      522240s      ext2            Linux/Windows data
101     524288s      526335s      2048s                        Linux Reserved
11      526336s      1048575s     522240s                      Linux/Windows data
102     1048576s     1050623s     2048s                        Linux Reserved
21      1050624s     1572863s     522240s                      Linux/Windows data
103     1572864s     1574911s     2048s                        Linux Reserved
31      1574912s     2097151s     522240s                      Linux/Windows data
 2      2097152s     4194303s     2097152s     ext4            Linux/Windows data
 5      4194304s     6291455s     2097152s     ext4            Linux/Windows data
 6      6291456s     10485759s    4194304s     ext4            Linux/Windows data
 7      10485760s    29360127s    18874368s    ext4            Linux/Windows data
 8      29360128s    31457279s    2097152s     ext4            Linux/Windows data
12      31457280s    33554431s    2097152s                     Linux/Windows data
15      33554432s    35651583s    2097152s                     Linux/Windows data
16      35651584s    39845887s    4194304s                     Linux/Windows data
17      39845888s    58720255s    18874368s                    Linux/Windows data
18      58720256s    60817407s    2097152s                     Linux/Windows data
22      60817408s    62914559s    2097152s                     Linux/Windows data
25      62914560s    65011711s    2097152s                     Linux/Windows data
26      65011712s    69206015s    4194304s                     Linux/Windows data
27      69206016s    88080383s    18874368s                    Linux/Windows data
28      88080384s    90177535s    2097152s                     Linux/Windows data
32      90177536s    92274687s    2097152s                     Linux/Windows data
35      92274688s    94371839s    2097152s                     Linux/Windows data
36      94371840s    98566143s    4194304s                     Linux/Windows data
37      98566144s    117440511s   18874368s                    Linux/Windows data
38      117440512s   119537663s   2097152s                     Linux/Windows data
50      119537664s   150994943s   31457280s                    Linux/Windows data
51      150994944s   182452223s   31457280s                    Linux/Windows data
52      182452224s   213909503s   31457280s                    Linux/Windows data
53      213909504s   245366783s   31457280s                    Linux/Windows data
54      245366784s   276824063s   31457280s                    Linux/Windows data
55      276824064s   308281343s   31457280s                    Linux/Windows data
56      308281344s   339738623s   31457280s                    Linux/Windows data
57      339738624s   371195903s   31457280s                    Linux/Windows data
58      371195904s   402653183s   31457280s                    Linux/Windows data
59      402653184s   434110463s   31457280s                    Linux/Windows data
90      434110464s   467664895s   33554432s    linux-swap(v1)  Linux swap
 9      467664896s   1953523711s  1485858816s  ext4            Linux/Windows data
128     1953523712s  1953525134s  1423s                        Linux Reserved

bash-4.1# df -a
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/root              1032088    206804    772856  22% /
proc                         0         0         0   -  /proc
sysfs                        0         0         0   -  /sys
/dev/sda1               252879     15181    224642   7% /boot
/dev/sda5              1032088     45136    934524   5% /var
/dev/sda6              2064208     92484   1866868   5% /var/log
/dev/sda7              9289080   6310612   2506612  72% /usr
/dev/sda8              1032088     34172    945488   4% /usr/local
/dev/sda9            731270632    201588 693922576   1% /home
tmpfs                  1893872         0   1893872   0% /dev/shm
bash-4.1#

piratesmack · 03-05-2011, 09:31 PM

Did your format the swap partition before running the installer?
http://www.linuxquestions.org/questi...7/#post4260866

Skaperen · 03-05-2011, 10:45 PM

Quote:

Originally Posted by piratesmack

Did your format the swap partition before running the installer?
http://www.linuxquestions.org/questi...7/#post4260866

Good point. I do believe I did, because it looks formatted and seems to be working. It has a UUID.

volkerdi · 03-06-2011, 01:31 PM

Tested here, and setup found swap space on /dev/sda19 GPT, which uses the higher 259 major number. I think /dev/sda90 should also work if the partition is formatted with mkswap first, but didn't have the patience to make that many partitions.

Skaperen · 03-06-2011, 01:52 PM

I tried repeating the install. Sometimes it detects the swap and sometimes it does not. I hate intermittent problems (more often it is hardware).

Skaperen · 03-06-2011, 01:56 PM

You can "jump" partitions and make just the numbers you want, at least for GPT and primary MBR partitions. I only have 41 partitions, with some numbered 90, 100, and 128. At least that is the case with the "gdisk" program I used (did not use "parted" except to list partitions).

But I definitely don't see sda90 having any more issues than sda19. It must be hardware on this cheap machine from Walmart I'm using for tests.

Darth Vader · 03-06-2011, 02:44 PM

For Gods sake, why someone will need 90 partitions in one disk?

I think that it's terrible inefficient this setup.

Just think about one thing: for every ext4 partition, kernel start a little daemon, to update the partition journal every 5 seconds (in a typical configuration). Now imagine 90 daemons yelling every 5 seconds that they want access to disk, of course, in different sections ...

Skaperen · 03-08-2011, 07:07 PM

Quote:

Originally Posted by Darth Vader

For Gods sake, why someone will need 90 partitions in one disk?

I think that it's terrible inefficient this setup.

Just think about one thing: for every ext4 partition, kernel start a little daemon, to update the partition journal every 5 seconds (in a typical configuration). Now imagine 90 daemons yelling every 5 seconds that they want access to disk, of course, in different sections ...

Who has 90 partitions?

Ramurd · 03-09-2011, 03:28 AM

Skaperen has 41 partitions, the numbers are not linear in his setup. Read the OP more carefully.
The question I'd have is: what kind of disks do you have, because 41 still seems a bit high to me and my not be supported in certain configurations. You may have to check the definitions and their limits. (e.g. IDE drives these maxima: either 4 primary partitions or 3 primary, 1 extended with 4 secondary = 7 effective partitions) other protocols may be different.

wildwizard · 03-09-2011, 04:37 AM

Quote:

Originally Posted by Ramurd

The question I'd have is: what kind of disks do you have, because 41 still seems a bit high to me and my not be supported in certain configurations.

He/She is using GPT so you can throw out the old thinking completely.

http://en.wikipedia.org/wiki/GUID_Partition_Table

Skaperen · 03-09-2011, 06:45 AM

Quote:

Originally Posted by wildwizard

He/She is using GPT so you can throw out the old thinking completely.

http://en.wikipedia.org/wiki/GUID_Partition_Table

You can do this with MBR, too. It's easy with the first 4 primary partitions. You can have just partition number 4 all by itself. It's technically possible with the logical partitions, too, but a couple programs I've tried it with (years ago) would not set it up. It's wasteful, too, because logical partitions are actually a nested layer of extended partitions. And they use up one of the primary slots.

GPT just makes things simple and easy. You get 128 slots and can use them pretty much as you please, in any order you please. Look at my partition table previously posted and you can see that the number order and allocation order are not the same. GPT handles this just fine (as did MBR, though doing so for logical partitions numbered 5 and up would be tricky and limited, and no tools I've seen can accomplish it for other than the 4 primary partitions).

BTW, it is said that MBR works only for drives up to 2TB. Reality is, it can work on any size drive, but limits the size of any partition to just under 2TB, and limits the starting sector of any partition to the sector just before the 2TB line. You could allocate nearly 4TB based on the structure of the MBR partition table format. However, I have found that partition tools end up doing calculations in error, probably as a result of 32 bit integer overflows, when pushing beyond the 2TB line. I haven't yet tested to see if the kernel itself would have an issue with MBR partitions running past the 2TB line.

The classic Linux device node numbering provided only 15 partitions for SCSI (SATA is classified as SCSI), but 63 for IDE. Several years ago I took advantage of that and set up a 27 partition box (a mix of Linux and BSD). How? I put BSD (label) partitions inside each of 4 MBR partitions. Linux saw them all (it does understand BSD labels from at least the popular BSD systems).

Quote:

Originally Posted by Ramurd

Skaperen has 41 partitions, the numbers are not linear in his setup. Read the OP more carefully.
The question I'd have is: what kind of disks do you have, because 41 still seems a bit high to me and my not be supported in certain configurations. You may have to check the definitions and their limits. (e.g. IDE drives these maxima: either 4 primary partitions or 3 primary, 1 extended with 4 secondary = 7 effective partitions) other protocols may be different.

This is a test box where I am setting up multiple installs, mostly Slackware, but also Debian, Fedora, and Ubuntu. There are 4 groups of partitions arranged for split filesystems (e.g. / /boot /var /var/log /usr /usr/local on different partitions). These are in 1 through 38 (not all numbers used). Then there are 10 single-partition systems numbered 50 to 59. These are intended for running in virtual machines but are being given partitions rather than files so I can, if needed, run or install them on the real hardware.

This is a 1TB SATA drive. I've installed the first 2 systems, Slackware64-current (on 1-8,9,90) and Slackware-current (on 11-18,9,90), and they are working fine, able to access every partition. The 3rd system will a multi-lib -current, and the 4th will be Slackware-current with a 64-bit kernel. Initially, I'm going to put old versions of Slackware in the 10 single-partition slots (on 50-59) just to shake things out.

The original post was because I encountered the problem with the swap space. I could work around it, but I was sure I had it set up right so it would be found. Turns out sometimes it works and sometimes not. I don't know the cause of that. When I run into something I'm not sure is, or is not, an issue, I post here to get information on other people's experiences with it, before I report it as a bug. Since it does work at least sometimes, I know the mechanism to detect it is there. As long as udev sets up the device nodes and the scanner looks at all devices listed in /proc/partitions, it should find it. And that seems to be in place (at first I was concerned it might not be). I don't know the cause of the failures I've seen now a couple times. Eventually, I'll have some time to dig into the installer so I can see where something might be failing. I do have a 2nd machine just like this one which is currently occupied with another project. That should be done soon, and I'm going to do the same setup on that one just to see if there are any hardware glitches (e.g. maybe the scan for swap trips up on hardware errors).

edit...

Oh, and the MBR partition table can keep going beyond 7 (whether IDE, SCSI, SATA, or whatever). I've done 12 before on IDE. In theory it can go on indefinitely. The way it works is that it starts with one of the 4 primary partitions being an extended type. Within that partition is another partition table which is designated to have 2 entries. One of these 2 entries defines how much of that extended partition is another nested extended partition, and the other is how much of that extended partition is a data partition. Now inside that nested extended parition just repeat the same thing with yet another partition table. Once you reach a level that lacks a deeper extended partition, you're done. The nested extended partition entries do not show up with numbers, and the data ones are numbered in order as you deeper, starting at 5.

piratesmack · 03-09-2011, 06:59 AM

FWIW, I created a new swap partition on my disk, and gave it number 90.
The Slackware installer detects mine every time.

Code:

# gdisk -l /dev/sda
GPT fdisk (gdisk) version 0.6.14

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.
Disk /dev/sda: 312581808 sectors, 149.1 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): C66D92FA-CAF0-4414-B895-87B694A1B02F
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 312581774
Partitions will be aligned on 2048-sector boundaries
Total free space is 77698669 sectors (37.0 GiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048            4095   1024.0 KiB  EF02  BIOS boot partition
   2            4096         2101247   1024.0 MiB  8200  Linux swap
   3         2101248        23072767   10.0 GiB    0700  Linux root
   4        23072768       232787967   100.0 GiB   0700  Linux home
  90       232787968       234885119   1024.0 MiB  8200  Linux swap

Skaperen · 03-09-2011, 09:58 AM

It's detecting mine most of the time. It's the 1st and 4th tries that it failed to. But because I had not yet seen a success after just the 1st try, I had a wide range of possible causes. I probably should have done more tries before posting here. When the other machine just like it gets done with its Ubuntu project, I'll redo all this on that machine and see what happens (these 2 machines are identical cheap $300 machines from Walmart). I have had one case of the system just not coming up at all from a power up, too (hung loading kernel). Re-seating cables might be in order.