Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Tue, 3 Nov 2009 11:57:10 paziulek wrote:
>
> I would like to create 2 copies of the primary in a "chain" configuration:
> ( sys1 mirror to sys2, sys2 mirror to sys3 - [same data on all] )
>
> sys1/sda10 -> sys2/sda10 -> sys3sda10
Below is my configuration that does exactly that.
> Q1: is there a way of mirroring the secondary?
> Q2: is there a way of mirroring primary to 2 secondaries? ( I am using drbd
> 0.7.5 on a 2.4.21 system )
Q1 - yes, see my configuration.
Q2 - AFAIK yes, with stacked primary (what I do on the secondary).
Also, I think it works on DRBD 8.3.x only (not on 7.x.x).
> and if somebody would ask why I would need such config:
> I want to mount the sdaX filesystem on sys3 in read-only mode to have access
> to semi-real-time data and at the same time have full mirror on sys2 with no
> sdaX access other than DRBD.
As far as my understanding of DRBD goes, you can not do that.
You can NOT mount (even read only) an updating secondary.
Ehud.
-------------------- /etc/drbd.conf --------------------
## lcl-nfs --> bu-lcl --> bu-rmt
common {
protocol A;
startup {
wfc-timeout 60;
}
disk {
on-io-error pass_on ;
no-disk-barrier ;
no-disk-flushes ;
# no-md-flushes;
no-disk-drain ;
}
net {
# this is the size of the tcp socket send buffer increase it _carefully_ !!
sndbuf-size 0;
rcvbuf-size 0;
# timeout 60; # 6 seconds (unit = 0.1 seconds)
# connect-int 10; # 10 seconds (unit = 1 second)
# ping-int 10; # 10 seconds (unit = 1 second)
# ping-timeout 5; # 500 ms (unit = 0.1 seconds)
max-buffers 8192;
unplug-watermark 8192;
# The highest number of data blocks between two write barriers.
max-epoch-size 8192;
data-integrity-alg "md5";
}
# rate is given in units of _byte_ not bit
syncer {
verify-alg md5 ;
# Configures the size of the active set. Each extent is 4M,
# 257 Extents ~> 1GB active set size.
# BTW, the hash algorithm works best if the number of al-extents is prime.
al-extents 499;
}
}
resource rmt {
disk {
## stack size 1459913168 K
## meta size 262144 K (256 MB)
size 1460175312K;
no-md-flushes ;
}
startup {
become-primary-on bu-lcl ;
}
# rate is given in units of _byte_ not bit
# slow line to Med1 - Max of 6MB
syncer {
rate 4M ;
}
on bu-lcl {
device /dev/drbd0;
disk /dev/sdb1;
address 192.168.0.84:7789;
meta-disk /dev/sda4[1];
}
on bu-rmt {
device /dev/drbd0;
disk /dev/md_d0p1;
address 192.168.1.87:7788;
meta-disk /dev/cciss/c0d0p3[0];
}
}
resource lcl {
disk {
size 1459913168K;
}
startup {
become-primary-on lcl-nfs ;
}
# rate is given in units of _byte_ not bit
syncer {
rate 30M ;
}
on lcl-nfs {
device /dev/drbd0;
disk /dev/sdb;
address 192.168.239.1:7789;
meta-disk internal;
}
stacked-on-top-of rmt {
device /dev/drbd1;
address 192.168.239.2:7788;
}
}
--
Ehud Karni Tel: +972-3-7966-561 /"\
Mivtach - Simon Fax: +972-3-7976-561 \ / ASCII Ribbon Campaign
Insurance agencies (USA) voice mail and X Against HTML Mail
http://www.mvs.co.il FAX: 1-815-5509341 / \
GnuPG: 98EA398D <http://www.keyserver.net/> Better Safe Than Sorry