[DRBD-user] Two newbie questions

Steve Thompson smt at vgersoft.com
Wed Aug 4 16:12:20 CEST 2010

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

New to DRBD; using it with two Dell PE2900 systems, CentOS 5.5 64-bit. Two 

(1) I am using dual back-to-back gigabits with mtu=9000 for replication 
with bonding in balance-rr mode with no issues. The documentation suggests 
that active-backup mode be used. I'm getting an iperf performance across 
this link of 1.97 Gbits/sec, and a drbd sync of a single volume gets about 
133 MB/sec, which is just a hair quicker than bonnie++ tells me that this 
file system can block-write. I'm interested in why the active-backup 
recommendation, and other folks' experiences with bonding.

(2) System A (primary) and system B (secondary). If B is shut down, A 
maintains a list of out-of-sync blocks for B. Where is this kept? If in 
the metadata (internal), how often is it updated on disk? If A is shut 
down and rebooted before B comes alive, any chance of losing any updates?

Steve Thompson                 E-mail:      smt AT vgersoft DOT com
Voyager Software LLC           Web:         http://www DOT vgersoft DOT com
39 Smugglers Path              VSW Support: support AT vgersoft DOT com
Ithaca, NY 14850
   "186,300 miles per second: it's not just a good idea, it's the law"

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