Hi, I have some questions about disabling write cache " http://ceph.com/docs/master/config-cluster/file-system-recommendations/
Ceph aims for data safety, which means that when the application receives notice that data was written to the disk, that data was actually written to the disk. For old kernels (<2.6.33), disable the write cache if the journal is on a raw disk. Newer kernels should work fine. Use hdparm to disable write caching on the hard disk: hdparm -W 0 /dev/hda 0 " Cache on journal disk: what happen if we have a powerfailure, if data are in cache of journal disk (ssd with/without supercapicitor) (so write is ack, but not really write on disk). Cache on disks storage: what happen if we have a powerfailure,if write is commited to journal, but write are in cache of storage disks and not yet on the platters ? Maybe the best way is to disable write cache on both (journal and storage disks) ? -Alexandre -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
