Date: Tue, 26 Jun 2012 15:04:20 +0100 From: "Steven Hartland" <killing@multiplay.co.uk> To: <freebsd-fs@FreeBSD.ORG> Subject: ZFS using sectorsize instead of stripesize for ashift Message-ID: <2194101A4F9946B496D921940B806486@multiplay.co.uk>
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We've been doing a lot test on ZFS with SSD's in particular around
trim. During this we've added quirks for our SSD's to cam/scsi_da
and was expecting this to ensure ZFS's ashift is set correctly
for newly create pools, instead of having to use the gnop
workaround.
Unfortunately this doesn't seem to be the case as ZFS is using the
geom providers sectorsize instead of stripesize as its minimum
transfer size (ashift).
The following patch corrects this behaviour so ZFS uses stripsize
for ashift definition.
So the question is this the correct thing to do?
If so should any of the other usages of sectorsize be changes to
stripesize as well?
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c.ashift 2012-06-26 13:38:55.193306961 +0000
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c 2012-06-26 13:39:22.323019022 +0000
@@ -504,7 +504,7 @@
/*
* Determine the device's minimum transfer size.
*/
- *ashift = highbit(MAX(pp->sectorsize, SPA_MINBLOCKSIZE)) - 1;
+ *ashift = highbit(MAX(pp->stripesize, SPA_MINBLOCKSIZE)) - 1;
/*
* Clear the nowritecache settings, so that on a vdev_reopen()
Regards
Steve
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