[DRBD-user] Identifying High iowait on DRBD Computers

yvette hirth yvette at dbtgroup.com
Fri Feb 18 01:05:47 CET 2011

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

Robinson, Eric wrote:

> Here's what I know so far: the iowait problem happens when the DRBD
> nodes are connected, even when they are both UpToDate.

Eric, you stated in an earlier email that this began happening some 
weeks ago, and before that, things were fine.

have you taken a cursory look at the operating environment (dasd space 
utilization, new application(s) being added or changed, new yum/apt-get 
upgrades (and product installs), etc?

when i'm stumped technically (which happens way too often!) i take a 
look at what else is going on with the environment, and it's amazing 
what one can find (a user:  "oh, right, we forgot to mention that app 
that was changed to read in the world and sort it", you know...)

if one of your apps / processes changed processing characteristics, or 
if one or more files grew too much, or ...  many things such as these 
could cause your system's "performance profile" to change.

i'm not defending drbd nor am i critical of it, and from all the emails 
i've read, your latest test seems to be in the right direction.  isolate 
the variables is usually the quickest route to solving performance issues.

just my €0.02.


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