Date: Wed, 10 Jul 2013 11:02:00 +0200 From: =?utf-8?Q?Dag-Erling_Sm=C3=B8rgrav?= <des@des.no> To: freebsd-fs@freebsd.org, freebsd-hackers@freebsd.org Cc: ivoras@freebsd.org Subject: Make ZFS use the physical sector size when computing initial ashift Message-ID: <86zjtupz3r.fsf@nine.des.no>
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The attached patch causes ZFS to base the minimum transfer size for a
new vdev on the GEOM provider's stripesize (physical sector size) rather
than sectorsize (logical sector size), provided that stripesize is a
power of two larger than sectorsize and smaller than or equal to
VDEV_PAD_SIZE. This should eliminate the need for ivoras@'s gnop trick
when creating ZFS pools on Advanced Format drives.
DES
--=20
Dag-Erling Sm=C3=B8rgrav - des@des.no
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Content-Type: text/x-patch
Content-Disposition: attachment; filename=zfs-vdev-stripesize.diff
Index: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
===================================================================
--- sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c (revision 253138)
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c (working copy)
@@ -578,6 +578,7 @@
{
struct g_provider *pp;
struct g_consumer *cp;
+ u_int sectorsize;
size_t bufsize;
int error;
@@ -661,8 +662,21 @@
/*
* Determine the device's minimum transfer size.
+ *
+ * This is a bit of a hack. For performance reasons, we would
+ * prefer to use the physical sector size (reported by GEOM as
+ * stripesize) as minimum transfer size. However, doing so
+ * unconditionally would break existing vdevs. Therefore, we
+ * compute ashift based on stripesize when the vdev isn't already
+ * part of a pool (vdev_asize == 0), and sectorsize otherwise.
*/
- *ashift = highbit(MAX(pp->sectorsize, SPA_MINBLOCKSIZE)) - 1;
+ if (vd->vdev_asize == 0 && pp->stripesize > pp->sectorsize &&
+ ISP2(pp->stripesize) && pp->stripesize <= VDEV_PAD_SIZE) {
+ sectorsize = pp->stripesize;
+ } else {
+ sectorsize = pp->sectorsize;
+ }
+ *ashift = highbit(MAX(sectorsize, SPA_MINBLOCKSIZE)) - 1;
/*
* Clear the nowritecache settings, so that on a vdev_reopen()
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