[DRBD-user] LVM, ext3, 3ware, Write Caching, and block sizes

Chris Miller drbd at scratchspace.com
Wed Jan 14 20:21:43 CET 2009

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

There was a recent thread that suggested a mismatch in the block sizes
between LVM (512b), and 3ware controllers (4kb). This is
apparently resolved (or helped) by enabling the write cache on the 3ware
controller. This effectively requires the battery backup unit for the
controller, unfortunately 3ware doesn't allow a BBU on their 2
port 9650SE (solder pads are there though...)

Is there a method of tuning the block sizes between the layers to free
up this bottleneck, or am I stuck (or better off) repartitioning the
disks and running ext3 directly on the disk?


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