Ian Collins wrote: > Richard Elling writes: >> >> I think the proposed timeouts here are too short, but the idea has >> merit. Note that such a preemptive read will have negative performance >> impacts for high-workload systems, so it will not be a given that people >> will want this enabled by default. Designing such a proactive system >> which remains stable under high workloads may not be trivial. > > Isn't this how things already work with mirrors? By this I mean > requests are issued to all devices and if the first returned data is > OK, the others are not required.
No. Yes. Sometimes. The details on choice of read targets varies by implementation. I've seen some telco systems which work this way, but most of the general purpose systems will choose one target for the read based on some policy: round-robin, location, etc. This way you could get the read performance of all disks operating concurrently. -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
