Bug 987484

Summary: RFE: Swap size limitation should be designated in man page mkswap
Product: Red Hat Enterprise Linux 6 Reporter: Michael Hood <mihood>
Component: util-linux-ngAssignee: Karel Zak <kzak>
Status: CLOSED WONTFIX QA Contact: qe-baseos-daemons
Severity: low Docs Contact:
Priority: unspecified    
Version: 6.6CC: dzhao, harald, hasuzuki, kazuhiro.sota, mihood, pschiffe, psklenar
Target Milestone: rcKeywords: FutureFeature, ManPageChange
Target Release: ---Flags: mihood: needinfo-
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Enhancement
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2016-04-06 09:12:08 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:

Description Michael Hood 2013-07-23 13:22:55 UTC
Description of problem:

The mkswap man page lists the maximum values for certain architectures but does not list that in RHEL 6 there is a 128GB limit. Customer got the follwoing error while trying to build a nes server:

???????????? Error Partitioning ?????????????
?                                            ?
? Could not allocate requested partitions:   ?
?                                            ?
? partition is too large for swap formatting ?
? (allowable size is 0 MB to 131072 MB).     ?                 
?                                            ?                 
? Press 'OK' to exit the installer.          ?


Version-Release number of selected component (if applicable):
Rhel 6.6

How reproducible:
NOTES
       The  maximum useful size of a swap area depends on the architecture and
       the kernel version.  It is roughly 2GiB on i386, PPC, m68k,  ARM,  1GiB
       on sparc, 512MiB on mips, 128GiB on alpha and 3TiB on sparc64. For ker-
       nels after 2.3.3 there is no such limitation.


Steps to Reproduce:
1.
2.
3.

Actual results:

man mkswap:

NOTES
       The  maximum useful size of a swap area depends on the architecture and
       the kernel version.  It is roughly 2GiB on i386, PPC, m68k,  ARM,  1GiB
       on sparc, 512MiB on mips, 128GiB on alpha and 3TiB on sparc64. For ker-
       nels after 2.3.3 there is no such limitation.




Expected results:

This should be a doc change in the man page. 


Additional info:

Comment 2 David Cantrell 2013-07-31 18:24:54 UTC
mkswap is owned by util-linux-ng.

We follow this formula for swap space calculation during automatic partitioning:
https://home.corp.redhat.com/wiki/swap-size-recommendations

Not sure if you want to mention that in the mkswap man page.

Comment 3 Karel Zak 2013-08-01 12:33:47 UTC
That's question if we want to maintain RHEL/fedora specific patches.

The man page mkswap.8 describes kernel limitations and I don't see reason why all our tools are not able to follow kernel and why we have any extra limitation defined by installer.

Anyway, I can add something like:

The size of the swap partition can be limited by system installer,   partitioning tool or another system component although kernel have no such limitation. See distribution specific documentation for more details.

Comments?

Comment 4 Karel Zak 2013-08-01 12:38:56 UTC
.. or 128GB is RHEL6 *kernel* limit?

Comment 6 Kazuhiro Sota 2014-09-04 04:12:19 UTC
It is not reproduced on the lvm.
Can only reproduce behavior on the physical partition.

Maybe a specification of the anaconda.