Solved gmirror swap doesn't boot

Ofloo · Jul 20, 2015

Every time, I enable gmirror swap, the system doesn't boot, when I enable it manually it doesn't complain and works fine?

Code:

% gpart show
=>  34  3907029101  ada0  GPT  (1.8T)
  34  6  - free -  (3.0K)
  40  1024  1  freebsd-boot  (512K)
  1064  4194304  2  freebsd-swap  (2.0G)
  4195368  3902833760  3  freebsd-zfs  (1.8T)
  3907029128  7  - free -  (3.5K)

=>  34  3907029101  ada1  GPT  (1.8T)
  34  6  - free -  (3.0K)
  40  1024  1  freebsd-boot  (512K)
  1064  4194304  2  freebsd-swap  (2.0G)
  4195368  3902833760  3  freebsd-zfs  (1.8T)
  3907029128  7  - free -  (3.5K)

Code:

% cat /etc/fstab
# Device       Mountpoint   FStype     Options   Dump   Pass#
/dev/mirror/swap     none     swap     sw   0   0
fdesc         /dev/fd     fdescfs     rw   0   0

Code:

% gmirror status
  Name  Status  Components
mirror/swap  COMPLETE  ada0p2 (ACTIVE)
  ada1p2 (ACTIVE)

wolfspam · Jul 23, 2015

Labeling your swap partitions may help with consistency between boots. Also, encrypting swap is a good idea.

Code:

# gmirror destroy swap
# gpart modify -l swap0 -i 2 ada0
# gpart modify -l swap1 -i 2 ada1
# gmirror label -F -h -b round-robin swap /dev/gpt/swap0 /dev/gpt/swap1

New /etc/fstab:

Code:

# Device Mountpoint FStype Options Dump Pass#

/dev/mirror/swap.eli none swap sw 0 0

fdesc /dev/fd fdescfs rw 0 0

wblock@ · Jul 23, 2015

gpart(8) does not have a label subcommand, it would be
gpart modify -l swap0 -i2 ada0
gpart modify -l swap1 -i2 ada1

The gmirror command is missing a name for the new mirror.

wolfspam · Jul 24, 2015

Oops, you're right. Got my geom(8) commands mixed up, I think that was supposed to be glabel(8), but that's also wrong. Should be fixed now.

Ofloo · Jul 25, 2015

And how would you introduce encryption to that swap? Isn't it useless since there isn't any disk encryption? Or is it a self generating key which changes each boot and is stored in real RAM?

tobik@ · Jul 25, 2015

Yes, if you add .eli to the swap device name in /etc/fstab it is automatically encrypted with a one-time key on each boot (see fstab(5) and geli(8)).

Ofloo · Jul 25, 2015

So for me, that would be:

Code:

/dev/mirror/swap.eli  none  swap  sw  0  0

wolfspam · Jul 25, 2015

Ofloo said:
So for me, that would be:

Code:

/dev/mirror/swap.eli none swap sw 0 0

Yes, Like in my previous example.

If you'd like a stronger key or a different encryption algorithm than the defaults (AES-XTS, 128) you can set it according to geli(8), like so:

Code:

/dev/mirror/swap.eli       none                    swap    sw,ealgo=Blowfish-CBC,keylen=448      0       0

Encrypting swap is not really useless in the absence of disk encryption, since it may contain personal information that was only stored in memory, including keys, user-names and passwords, which can be easily recovered from the disk. Since it's painless to implement in FreeBSD, I don't see any reason not to do it.

Ofloo · Jul 28, 2015

Nice, thank you very much.