Swap partition for FreeBSD
smithi at nimnet.asn.au
Sat May 16 16:54:05 UTC 2015
In freebsd-questions Digest, Vol 571, Issue 6
On Sat, 16 May 2015 15:16:56 +0530 Avinash Sonawane <rootkea at gmail.com> wrote:
Avinash, I'm cutting various bits out of this digest, because I can :)
In response to Matthew Seaman <matthew at freebsd.org> you wrote:
> When I tried to delete the said partition from freebsd as `gpart
> delete -i 2878773 ada0s4` it says "gpart: pre-check failed: Operation
-i there shouldn't be a block number, from my reading of gpart(8) on
9.3, but I'm not sure how exactly delete ada0s6 should be crafted, if
it's possible with your kernel as is (below). (yoo hoo, Warren!)
> canceled". So I booted to Debian and deleted that partition using
> Gparted and then when I tried to create freebsd-swap in FreeBSD (from
> previously freed 8GB) as `gpart add -t freebsd-swap -b 181362690
> ada0s4` it again said "gpart: pre-check failed: Operation canceled"
> After searching a bit on the web I came to know that default kernel
> build options specify "options GEOM_PART_EBR_COMPAT" which prevents
> GEOM from editing EBR partition schemes. So to create a partition of
> type freebsd-swap in extended partition it looks like I need to
> recompile the kernel without the GEOM_PART_EBR_COMPAT kernel option.
> Any other way beside this?
Possibly not - and it's not clear to me from descriptions in gpart(8)
that even if you just had GEOM_PART_EBR in kernel (see /sys/conf/NOTES)
that you will be able to access ada0s6, nor whether - even if you can,
R/W, for data - that it would be supported for swap anyway.
Last time I used (then called) Extended Partitions was pre-GEOM and
pre-FUSE, where a DEFAULT kernel with a compiled module worked fine
mounting and reading NTFS and/or HPFS partitions - I had many of the
latter from OS/2 to recover to UFS - when reading was fine but writing
was 'experimental' and not then to be relied upon.
> > There's no formatting required for a swap area: the system just uses it
> > as a blob of available space and writes what it needs to.
> Ok. But I am getting really annoyed by that error message during boot
> and and a feeling that my 8GB freebsd swap partition won't be able to
> store the kernel dumps.
> >> I was trying to build www/webkit-gtk3 (a dependency for x11/gnome3)
> >> then it abruptly exited with "Out of swap space error" so I created a
> >> separate 8GB partition to be used as freebsd-swap.
> > Why don't use a regular file as swap?
> Because I read somewhere that swap partition is much more faster than
> swap file and given that I already have 4GB RAM and then too I was
> posed with "out of RAM/swap space" like error (which I never
> anticipated) I wanted a more and faster swap. So dedicated swap
In the long run, when you get this sorted out, sure, but meanwhile a
swapfile is almost infinitely better than no swap at all :)
> May be this will justify:
Sure, though there is some dispute there too .. worry about that later.
In response to Polytropon <freebsd at edvax.de> you wrote:
> I have 4 Primary partitions. Out of which one ada0s1 has FreeBSD,
> ada0s2 has Debian, ada0s3 is one extra Primary partition (which
> currently holds data) and ada0s4 is an extended partition (to create
> further logical partitions like linux-swap, data partitions etc.)
Understandable, with that mix of systems.
> > Typically, you use _one_ "DOS primary partition" - in BSD
> > called a slice - to carry the FreeBSD filesystems _and_ the
> > swap partition, for example:
> > ada0s1a = /
> > ada0s1b = swap <- not a separate slice!
> > ada0s1d = /tmp
> > ada0s1e = /var
> > ada0s1f = /usr
> > ada0s1g = /home
Unfortunately that sort of sub-partitioning is almost unknown now, as
bsdinstall defaults to the usually totally inappropriate linux-style
single / partition, requiring certain learned magic to install such a
scheme. You were bitten by this, as you have no part of ada0s1 that you
can delete, or backup separately using dump & restore, and/or resize.
However the default install normally includes a swap partition too.
> > With gpart or (the old-fashioned) fdisk, you would create
> > the slice, then use bsdlabel to create the partitions inside
> > that slice. Those that are _not_ swap partitions would then
> > be formatted with a UFS file system; swap doesn't need to be
> > formatted.
Even if using fdisk to create / manage slices, you are likely much
better off using gpart -s bsd instead of bsdlabel thereafter - see:
> > It seems to be that way. Using "extended DOS partitions" has never
> > been a good idea. :-)
Maybe not, but I may have headed into Linuxland without that support :)
> I have Freebsd installed in ada0s1a so can I create ada0s1b inside
> ada0s1 to have freebsd-swap? How do I do that?
With only a single / on that slice it's backup, redo the partitioning
leaving room for swap, and restoring. Good practice, anyway :)
> Or should I create ada0s6b as swap partition inside ada0s6 slice?
I have serious doubts that will work - but you can try, for education :)
Another option perhaps, quoting from your http://pastebin.com/KSFM49yP
#gpart show -p
=> 63 976773105 ada0 MBR (466G)
63 195035085 ada0s1 freebsd [active] (93G)
195035148 718836 - free - (351M)
195753984 193753088 ada0s2 linux-data (92G)
389507072 191754240 ada0s3 linux-data (91G)
581261312 2046 - free - (1.0M)
581263358 395507714 ada0s4 ebr (189G)
976771072 2096 - free - (1.0M)
=> 0 195035085 ada0s1 BSD (93G)
0 195035084 ada0s1a freebsd-ufs (93G)
195035084 1 - free - (512B)
=> 0 395507714 ada0s4 EBR (189G)
0 181362690 ada0s5 ntfs (86G)
181362690 16777216 ada0s6 linux-data (8.0G)
198139906 189368320 ada0s7 ntfs (90G)
387508226 7999488 ada0s8 linux-swap (3.8G)
Could ada0s2 be a bit (like 8GB) smaller? If so you could backup - tar
I guess - and delete ada0s2, extend ada0s1 - backed up, dumped from /
and deleted - then readd ada0s2 and restore both. Pretty messy unless
you have somewhere handy to shunt such big backups, but I guess you do?
If you can rearrange any of your linux (or ntfs) space somewhat to suit
FreeBSD's (at least) reticence to use anything on ada0s4, you should be
able to get something reasonable. Otherwise yes you'll need to fit swap
into ada0s1 93GB - however you should be able to share common data with
either linux-data slice; not at all sure about accessing ntfs on EBR ..
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