e770bc6bf5
arrangement that has no intrinsic internal knowledge of whether devices it is given are truly multipath devices. As such, this is a simplistic approach, but still a useful one. The basic approach is to (at present- this will change soon) use camcontrol to find likely identical devices and and label the trailing sector of the first one. This label contains both a full UUID and a name. The name is what is presented in /dev/multipath, but the UUID is used as a true distinguishor at g_taste time, thus making sure we don't have chaos on a shared SAN where everyone names their data multipath as "Fred". The first of N identical devices (and N *may* be 1!) becomes the active path until a BIO request is failed with EIO or ENXIO. When this occurs, the active disk is ripped away and the next in a list is picked to (retry and) continue with. During g_taste events new disks that meet the match criteria for existing multipath geoms get added to the tail end of the list. Thus, this active/passive setup actually does work for devices which go away and come back, as do (now) mpt(4) and isp(4) SAN based disks. There is still a lot to do to improve this- like about 5 of the 12 recommendations I've received about it, but it's been functional enough for a while that it deserves a broader test base. Reviewed by: pjd Sponsored by: IronPort Systems MFC: 2 months
100 lines
3.4 KiB
C
100 lines
3.4 KiB
C
/*-
|
|
* Copyright (c) 2006-2007 Matthew Jacob <mjacob@FreeBSD.org>
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
/*
|
|
* Based upon work by Pawel Jakub Dawidek <pjd@FreeBSD.org> for all of the
|
|
* fine geom examples, and by Poul Henning Kamp <phk@FreeBSD.org> for GEOM
|
|
* itself, all of which is most gratefully acknowledged.
|
|
*/
|
|
|
|
#ifndef _G_MULTIPATH_H_
|
|
#define _G_MULTIPATH_H_
|
|
|
|
#define G_MULTIPATH_CLASS_NAME "MULTIPATH"
|
|
#define G_MULTIPATH_VERSION 1
|
|
#define G_MULTIPATH_MAGIC "GEOM::MULTIPATH"
|
|
|
|
#include <sys/endian.h>
|
|
|
|
#ifdef _KERNEL
|
|
|
|
struct g_multipath_softc {
|
|
struct g_provider * pp;
|
|
struct g_consumer * cp_active;
|
|
char sc_name[16];
|
|
char sc_uuid[40];
|
|
};
|
|
#endif /* _KERNEL */
|
|
|
|
struct g_multipath_metadata {
|
|
char md_magic[16]; /* Magic Value */
|
|
char md_uuid[40]; /* more magic */
|
|
char md_name[16]; /* a friendly name */
|
|
uint32_t md_version; /* version */
|
|
uint32_t md_sectorsize; /* sectorsize of provider */
|
|
uint64_t md_size; /* absolute size of provider */
|
|
};
|
|
|
|
static __inline void
|
|
multipath_metadata_encode(const struct g_multipath_metadata *, u_char *);
|
|
|
|
static __inline void
|
|
multipath_metadata_decode(u_char *, struct g_multipath_metadata *);
|
|
|
|
static __inline void
|
|
multipath_metadata_encode(const struct g_multipath_metadata *md, u_char *data)
|
|
{
|
|
bcopy(md->md_magic, data, sizeof(md->md_magic));
|
|
data += sizeof(md->md_magic);
|
|
bcopy(md->md_uuid, data, sizeof(md->md_uuid));
|
|
data += sizeof(md->md_uuid);
|
|
bcopy(md->md_name, data, sizeof(md->md_name));
|
|
data += sizeof(md->md_name);
|
|
le32enc(data, md->md_version);
|
|
data += sizeof(md->md_version);
|
|
le32enc(data, md->md_sectorsize);
|
|
data += sizeof(md->md_sectorsize);
|
|
le64enc(data, md->md_size);
|
|
}
|
|
|
|
static __inline void
|
|
multipath_metadata_decode(u_char *data, struct g_multipath_metadata *md)
|
|
{
|
|
bcopy(data, md->md_magic, sizeof(md->md_magic));
|
|
data += sizeof(md->md_magic);
|
|
bcopy(data, md->md_uuid, sizeof(md->md_uuid));
|
|
data += sizeof(md->md_uuid);
|
|
bcopy(data, md->md_name, sizeof(md->md_name));
|
|
data += sizeof(md->md_name);
|
|
md->md_version = le32dec(data);
|
|
data += sizeof(md->md_version);
|
|
md->md_sectorsize = le32dec(data);
|
|
data += sizeof(md->md_sectorsize);
|
|
md->md_size = le64dec(data);
|
|
}
|
|
#endif /* _G_MULTIPATH_H_ */
|