[DRBD-user] DRBD and 3Ware cards

Jeff Buck jeffb at umci.com
Thu Aug 25 18:33:09 CEST 2005

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

On Mon, 2005-08-22 at 09:53 -0400, Yves Trudeau wrote:
>     what you say is exact during the sync operation.  During that phase, 
> I can literaly freeze the server for a long time (up to 15 minutes) just 
> buy copying a large file (> 5 GB).  I this is cause by the dirty write 
> cache of Linux which defaults to 30% of physical RAM (in ou case 
> 4GB*30%).  But once in "consistent" state,  everything seems to be 
> normal, replication is almost as fast as transfering a file from the 
> network.  It seems to me that DRBD/3Ware is slow when DRBD has to read 
> the data on the disk before transfering it to the other node.  If the 
> data just comes through DRBD and then sent to the local et remote drive, 
> performance is OK.
Good, I'm glad yours clears up. Our test server was harder to freeze,
but still froze up periodically under heavy load even after the full
sync was done.  Most of our tests were with 8 port 85xx series cards,
but we did try the 95xx series cards for a couple days.


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