Messages in this thread | | | Date | Tue, 31 Mar 2009 15:25:28 -0400 | From | Mark Lord <> | Subject | Re: [PATCH 1/7] block: Add block_flush_device() |
| |
Ric Wheeler wrote: .. > As Mark pointed out, most S-ATA/SAS drives will flush the write cache > when they see a bus reset so even without barriers, the cache will be > preserved (or flushed) after a reboot or panic. Power outages are the > problem barriers/flushes are meant to help with. ..
I still see barriers as a separate issue from flushes. Flushes are there for power failures and hot-removable devices.
Barriers are there for that, but also for better odds of data integrity in the even of a filesystem or kernel crash.
Even if I don't want the kernel needlessly flushing my battery-backed write caches, I still do want the barrier ordering that improves the odds of filesystem consistency in the event of a kernel crash.
Cheers
| |