From 2959d94a0a53612cc1ca9ce9d17df26c3d69a513 Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Fri, 1 Oct 2010 10:57:56 -0700 Subject: Add FAILFAST support ZFS works best when it is notified as soon as possible when a device failure occurs. This allows it to immediately start any recovery actions which may be needed. In theory Linux supports a flag which can be set on bio's called FAILFAST which provides this quick notification by disabling the retry logic in the lower scsi layers. That's the theory at least. In practice is turns out that while the flag exists you oddly have to set it with the BIO_RW_AHEAD flag. And even when it's set it you may get retries in the low level drivers decides that's the right behavior, or if you don't get the right error codes reported to the scsi midlayer. Unfortunately, without additional kernels patchs there's not much which can be done to improve this. Basically, this just means that it may take 2-3 minutes before a ZFS is notified properly that a device has failed. This can be improved and I suspect I'll be submitting patches upstream to handle this. --- etc/Makefile.in | 1 + 1 file changed, 1 insertion(+) (limited to 'etc') diff --git a/etc/Makefile.in b/etc/Makefile.in index f5835b395..5eb555171 100644 --- a/etc/Makefile.in +++ b/etc/Makefile.in @@ -44,6 +44,7 @@ am__aclocal_m4_deps = \ $(top_srcdir)/config/kernel-bdev-logical-size.m4 \ $(top_srcdir)/config/kernel-bio-empty-barrier.m4 \ $(top_srcdir)/config/kernel-bio-end-io-t-args.m4 \ + $(top_srcdir)/config/kernel-bio-failfast.m4 \ $(top_srcdir)/config/kernel-bio-rw-syncio.m4 \ $(top_srcdir)/config/kernel-blk-end-request.m4 \ $(top_srcdir)/config/kernel-blk-fetch-request.m4 \ -- cgit v1.2.3