On Friday February 1, aristizb@xxxxxxxxxxx wrote: > > > Summarizing, I have two questions about the behavior of Linux md with > slow devices: > > 1. Is it possible to modify some kind of time-out parameter on the > mdadm tool so the slow device wouldn't be marked as faulty because of > its slow performance. No. md doesn't do timeouts at all. The underlying device does. So if you are getting time out errors from the iscsi initiator, then you need to change the timeout value used by the iscsi initiator. md has no part to play in this. It just sends a request and eventually gets either 'success' or 'fail'. > > 2. Is it possible to control the "buffer" size of the RAID?, in other > words, can I control the amount of data I can write to the local disc > before I receive an acknowledgment from the slow device when I am > using the write-behind option. No. md/raid1 simply calls 'kmalloc' to get space to buffer each write as the write arrives. If the allocation succeeds, it is used to perform the write lazily. If the allocation fails, the write is performs synchronously. What did you hope to achieve by such tuning? It can probably be added if it is generally useful. NeilBrown - 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
