Lars Ellenberg a écrit :
GAUTIER Hervé a écrit :Hi,I Would like to understand well the following message which appears to me during a resync:local disk flush failed with status -95 errno.h seems to say:#define EOPNOTSUPP 95 /* Operation not supported on transport endpoint */After some research, I have understood that this is in relation with "I/O barriers".If I've got this message, there is something (OS, driver, disk, ...) in my system which does not support "I/O barriers", does it ?right. drbd cannot use barriers where it would want to. so it falls back to instead "let IO drain and hope for the best". drbd used to do that anyways up to 8.0.9 or so, and assumed you have a "safe" device (no volatile caches involved). my recommendation: get a decent raid controller with a battery backed write cache, switch off all volatile caches in the chain (on the single drives), and forget about the whole issue. btw, drbd itself does not yet support barriers for upper layers either. but we are working on that...
Thank you very much for the explanation and advices. How could I know from where comes the barrier problem ?I have identified the following different level of the chain that may be involved: - OS: I am currently running on Red Hat Enterprise Linux ES release 4 (Nahant Update 6) kernel 2.6.9-67.ELsmp. Is there a minimum required kernel version for the barriers implementation ?
- DRBD: The current version I am using is drbd-8.2.5.- Drivers: I currently use disks connected on a HP Smart Array 642 Controller using the cciss driver 2.6.16 provided by the Red Hat Enterprise Linux ES release 4 (Nahant Update 6). I haven't seen any option on this driver. - Controller: I will check in there is any cache option in the HP Smart Array 642 Controller firmware. - Disks: I will try to find any information on the disks used in order to check if the used some cache.
Anything else I have forgotten ? Thank in advance, Best regards. -- Hervé GAUTIER _______________________________________________ drbd-user mailing list drbd-user@xxxxxxxxxxxxxxxx http://lists.linbit.com/mailman/listinfo/drbd-user