Hi, I don't have a deep knowledge about filesystems and I've few experiences with raid configuration, so I need someone who can answear some questions about write back cache and barriers. I have two sata hd (sda, sdb) configured in bios-raid 0 and relative device created by dmraid on boot (nvidia_ihfaaicb). (1) what should I do to know if the write back cache is enabled or not ? (2) if the write cache is enabled on both sda and sdb this mean that is enabled also on the raid device (/dev/mapper/nvidia_ihfaaicb) ? (3) how should I do to enable/disable the write cache on the raid device ? If I try mounting a xfs filesystem I get a message like "barriers are not supported by this device" but if I mount a ext3 or a reiserfs filesystem respectively with options barrier=1 and barrier=flush they don't complain. If I mount the reiserfs I explicity get a message like "using barriers". So who tells the truth ?? (4) is there a way to know if the raid device supports barrier or not ? (5) is there a (not dangerous) test I can do to figure out if barriers are really enabled and used with ext3 and reiserfs filesystems ? Thanks for reading the message Marco - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
