[DRBD-user] kjournald getting stuck in sync_buffer on a drbd device

Lars Kellogg-Stedman lars at seas.harvard.edu
Thu Apr 24 21:14:15 CEST 2008

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


Howdy,

I've recently had access to a filesystem on a DRBD device freeze up on  
two separate systems, and I wanted to see if anyone else has  
encountered this behavior.  Both systems are running CentOS 5, with  
kernel 2.6.18-53.1.14.el5 and drbd 8.2.5.

On two occasions, an attempt to "ls" a filesystem hung.  I found  
kjournald stuck in sync_buffer:

   # ps -o pid,state,wchan:20,cmd -e | grep D
   PID S WCHAN                CMD
    3021 D sync_buffer          [kjournald]
    6478 D get_write_access     ls --color=tty

After several minutes (5?), things would eventually start working  
again.  While experiencing the problem, /proc/drbd looked like this:

version: 8.2.5 (api:88/proto:86-88)
GIT-hash: 9faf052fdae5ef0c61b4d03890e2d2eab550610c build by  
buildsvn at c5-x8664-build, 2008-03-09 10:16:01
  0: cs:Connected st:Secondary/Primary ds:UpToDate/UpToDate C r---
     ns:3920 nr:4320648 dw:4324568 dr:4526 al:9 bm:270 lo:0 pe:0 ua:0  
ap:0
	resync: used:0/31 hits:272417 misses:288 starving:0 dirty:0 changed:288
	act_log: used:0/127 hits:971 misses:9 starving:0 dirty:0 changed:9
  1: cs:Connected st:Primary/Secondary ds:UpToDate/UpToDate C r---
     ns:4269080 nr:0 dw:132640 dr:4137225 al:49 bm:293 lo:0 pe:2 ua:0  
ap:2
	resync: used:0/31 hits:272762 misses:283 starving:0 dirty:0 changed:283
	act_log: used:1/127 hits:33111 misses:55 starving:0 dirty:6 changed:49

(The problem occurred on drbd1, for which this system is primary).

Has anyone seen this before?

-- 
Lars Kellogg-Stedman <lars at seas.harvard.edu>
Manager, IT Engineering
Harvard University School of Engineering and Applied Sciences (SEAS)






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