[DRBD-user] Please Help With /dev/drbd0

Nick Khamis symack at gmail.com
Sun Sep 11 00:31:47 CEST 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Hello Everyone,

I always stuggle with linux paritions, and I am hoping you guys can
help e with this.
Following a few howtos to get wind of it all, on fresh installations I have:

/boot
/
/swap
/drbd          -> /dev/sda7
/service      -> /dev/sda8


fstab
                                                proc            /proc
         proc    defaults                0       0
/               ext3    errors=remount-ro                       0       1
/boot           ext3    defaults                                0       2
/drbd           ext3    defaults                                0       2
/service        ext3    noauto                                  0       0
none            swap    sw                                      0       0
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto         0       0

mtab

/dev/sda5 / ext3 rw,errors=remount-ro 0 0
tmpfs /lib/init/rw tmpfs rw,nosuid,mode=0755 0 0
proc /proc proc rw,noexec,nosuid,nodev 0 0
sysfs /sys sysfs rw,noexec,nosuid,nodev 0 0
udev /dev tmpfs rw,mode=0755 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
devpts /dev/pts devpts rw,noexec,nosuid,gid=5,mode=620 0 0
/dev/sda1 /boot ext3 rw 0 0


resource r0.res {
  on mydrbd1 {
    device    /dev/drbd0;
    disk      /dev/sda8;
    address   192.168.2.105:7789;
    meta-disk /dev/sda7 [0];
  }
  on mydrbd2 {
    device    /dev/drbd0;
    disk      /dev/sda8;
    address   192.168.2.106:7789;
    meta-disk /dev/sda7 [0];
  }
}

1) I created sda7 for meta disk, and sda8 as the disk that needs to be
replicated.
2) I had, and still having trouble with /dev/drbd0, where did this
little fellow come from? I was kind of taken by surprise
After switching the primary role from mydrbd1 to mydrbd2 and vice
versa, I was able to partition the drive on both nodes.
This was not documented anywhere. The partition is 46936 1K blocks.
I see that there is meta data information created in /dev/drbd I am
not sure where this partition came from either.

Grinidng forward. One of the nodes are mounted to /service the other
one is read only. Makes sense ext3... But still no replication

root at mydrbd2:/service# /etc/init.d/drbd status
drbd driver loaded OK; device status:
version: 8.3.7 (api:88/proto:86-91)
srcversion: EE47D8BF18AC166BE219757
m:res     cs         ro                 ds                 p  mounted   fstype
0:r0_res  Connected  Primary/Secondary  UpToDate/UpToDate  C  /service  ext3

version: 8.3.7 (api:88/proto:86-91)
srcversion: EE47D8BF18AC166BE219757
 0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r----
    ns:103660 nr:2473108 dw:2576768 dr:429 al:37 bm:145 lo:0 pe:0 ua:0
ap:0 ep:1 wo:b oos:0

Can some give me the bigger picture here please?

Cheers,

Nicholas.



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