Hi, I'm planning to user bcache for speed, and drbd for HA between two nodes. I'm facing with this question: Is it better to have drbd on top of a bcached volume(caching + backing device) or to use bcache to put a caching device on top of a drbd backing device? I think that with the second option and writeback enabled, write requests should be faster than with the first option... Do you agree? But.. what about the data integrity and consistency of the data on the drbd slave volume? What if the power goes down on the master node? Could the drbd volume on the slave node, get corrupted If the caching device is not detached correctly on the master node? On the contrary with the first option(drbd on top of bcache), I think drbd should always preserve data integrity on the two nodes, isn't it? Can bcache with writeback mode, cause corrupted data on both nodes in case of a ssd, or power unit failure? And where is it better to put drbd metadata? External or internal? External to ssd is the obvious answer, but if I want to store them internally, what will be the advantages and disadvantages of the two solutions? With the first option, storing metadata internally on the bcached device should not be so slow, given that bcache should always cache most used data. Isn't it? What do you think about this subject? -- Giovanni Lenzi -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
