[DRBD-user] Re: DRBD doesn't seem to scale to fast underlying hardware with typical database load

Casey Allen Shobe cshobe at bepress.com
Sat Aug 9 20:44:25 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.

On Aug 9, 2008, at 11:21 AM, Casey Allen Shobe wrote:
> * Maybe JFS is a bad choice to use on top of DRBD (kind of doubt it)  
> and we should use another filesystem who's disk accesses match  
> DRBD's expectations better.

After sending this E-mail, I decided to mkfs.ext3 the partition (with  
DRBD slave connected).  It got to the "writing inode tables" part,  
shot up to 1200 pretty fast and then stuck.  It's now been CRAWLING  
along at a snail's pace for a good 10 minutes now, and is not yet up  
to 2000 (out of 5465, so I expect it will be the better part of an  
hour or more before it completes, which seems absolutely absurd for an  
mkfs).  Additionally, I tried disconnecting the slave midway through  
and speed did not improve.

So the problem seems lower-level than the filesystem (just wanted to  
rule that out).

It also seems, since performance is terrible even when the slave is  
disconnected, that the network is not a factor.

The mkfs alone is pushing the server load up to 3.0, however the CPU  
utilization is sticking at 0%, so CPU does not seem to be a factor  

Casey Allen Shobe
Database Architect, The Berkeley Electronic Press
cshobe at bepress.com (email/jabber/aim/msn)
http://www.bepress.com | +1 (510) 665-1200 x163

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