diff options
Diffstat (limited to 'lib/geom/virstor')
| -rw-r--r-- | lib/geom/virstor/Makefile | 9 | ||||
| -rw-r--r-- | lib/geom/virstor/Makefile.depend | 16 | ||||
| -rw-r--r-- | lib/geom/virstor/geom_virstor.c | 541 | ||||
| -rw-r--r-- | lib/geom/virstor/gvirstor.8 | 297 |
4 files changed, 863 insertions, 0 deletions
diff --git a/lib/geom/virstor/Makefile b/lib/geom/virstor/Makefile new file mode 100644 index 000000000000..63ea8e5ad31c --- /dev/null +++ b/lib/geom/virstor/Makefile @@ -0,0 +1,9 @@ +PACKAGE=geom +.PATH: ${SRCTOP}/sys/geom/virstor + +GEOM_CLASS= virstor + +SRCS+= binstream.c +SRCS+= g_virstor_md.c + +.include <bsd.lib.mk> diff --git a/lib/geom/virstor/Makefile.depend b/lib/geom/virstor/Makefile.depend new file mode 100644 index 000000000000..0dd05cace3c0 --- /dev/null +++ b/lib/geom/virstor/Makefile.depend @@ -0,0 +1,16 @@ +# Autogenerated - do NOT edit! + +DIRDEPS = \ + include \ + include/xlocale \ + lib/${CSU_DIR} \ + lib/libc \ + lib/libcompiler_rt \ + lib/libgeom \ + + +.include <dirdeps.mk> + +.if ${DEP_RELDIR} == ${_DEP_RELDIR} +# local dependencies - needed for -jN in clean tree +.endif diff --git a/lib/geom/virstor/geom_virstor.c b/lib/geom/virstor/geom_virstor.c new file mode 100644 index 000000000000..5f5087e99213 --- /dev/null +++ b/lib/geom/virstor/geom_virstor.c @@ -0,0 +1,541 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2005 Ivan Voras <ivoras@freebsd.org> + * + * 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. + */ + +#include <sys/param.h> +#include <errno.h> +#include <paths.h> +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <strings.h> +#include <fcntl.h> +#include <unistd.h> +#include <libgeom.h> +#include <err.h> +#include <assert.h> + +#include <core/geom.h> +#include <misc/subr.h> + +#include <geom/virstor/g_virstor_md.h> +#include <geom/virstor/g_virstor.h> + +uint32_t lib_version = G_LIB_VERSION; +uint32_t version = G_VIRSTOR_VERSION; + +#define GVIRSTOR_CHUNK_SIZE "4M" +#define GVIRSTOR_VIR_SIZE "2T" + +#if G_LIB_VERSION == 1 +/* Support RELENG_6 */ +#define G_TYPE_BOOL G_TYPE_NONE +#endif + +/* + * virstor_main gets called by the geom(8) utility + */ +static void virstor_main(struct gctl_req *req, unsigned flags); + +struct g_command class_commands[] = { + { "clear", G_FLAG_VERBOSE, virstor_main, G_NULL_OPTS, + "[-v] prov ..." + }, + { "dump", 0, virstor_main, G_NULL_OPTS, + "prov ..." + }, + { "label", G_FLAG_VERBOSE | G_FLAG_LOADKLD, virstor_main, + { + { 'h', "hardcode", NULL, G_TYPE_BOOL}, + { 'm', "chunk_size", GVIRSTOR_CHUNK_SIZE, G_TYPE_NUMBER}, + { 's', "vir_size", GVIRSTOR_VIR_SIZE, G_TYPE_NUMBER}, + G_OPT_SENTINEL + }, + "[-h] [-v] [-m chunk_size] [-s vir_size] name provider0 [provider1 ...]" + }, + { "destroy", G_FLAG_VERBOSE, NULL, + { + { 'f', "force", NULL, G_TYPE_BOOL}, + G_OPT_SENTINEL + }, + "[-fv] name ..." + }, + { "stop", G_FLAG_VERBOSE, NULL, + { + { 'f', "force", NULL, G_TYPE_BOOL}, + G_OPT_SENTINEL + }, + "[-fv] name ... (alias for \"destroy\")" + }, + { "add", G_FLAG_VERBOSE, NULL, + { + { 'h', "hardcode", NULL, G_TYPE_BOOL}, + G_OPT_SENTINEL + }, + "[-vh] name prov [prov ...]" + }, + { "remove", G_FLAG_VERBOSE, NULL, G_NULL_OPTS, + "[-v] name ..." + }, + G_CMD_SENTINEL +}; + +static int verbose = 0; + +/* Helper functions' declarations */ +static void virstor_clear(struct gctl_req *req); +static void virstor_dump(struct gctl_req *req); +static void virstor_label(struct gctl_req *req); + +/* Dispatcher function (no real work done here, only verbose flag recorder) */ +static void +virstor_main(struct gctl_req *req, unsigned flags) +{ + const char *name; + + if ((flags & G_FLAG_VERBOSE) != 0) + verbose = 1; + + name = gctl_get_ascii(req, "verb"); + if (name == NULL) { + gctl_error(req, "No '%s' argument.", "verb"); + return; + } + if (strcmp(name, "label") == 0) + virstor_label(req); + else if (strcmp(name, "clear") == 0) + virstor_clear(req); + else if (strcmp(name, "dump") == 0) + virstor_dump(req); + else + gctl_error(req, "%s: Unknown command: %s.", __func__, name); + + /* No CTASSERT in userland + CTASSERT(VIRSTOR_MAP_BLOCK_ENTRIES*VIRSTOR_MAP_ENTRY_SIZE == MAXPHYS); + */ +} + +/* + * Labels a new geom Meaning: parses and checks the parameters, calculates & + * writes metadata to the relevant providers so when the next round of + * "tasting" comes (which will be just after the provider(s) are closed) geom + * can be instantiated with the tasted metadata. + */ +static void +virstor_label(struct gctl_req *req) +{ + struct g_virstor_metadata md; + off_t msize; + unsigned char *sect; + unsigned int i; + size_t ssize, secsize; + const char *name; + char param[32]; + int hardcode, nargs, error; + struct virstor_map_entry *map; + size_t total_chunks, write_max_map_entries; + unsigned int map_chunks; /* Chunks needed by the map (map size). */ + size_t map_size; /* In bytes. */ + ssize_t written; + int fd; + + nargs = gctl_get_int(req, "nargs"); + if (nargs < 2) { + gctl_error(req, "Too few arguments (%d): expecting: name " + "provider0 [provider1 ...]", nargs); + return; + } + + hardcode = gctl_get_int(req, "hardcode"); + + /* + * Initialize constant parts of metadata: magic signature, version, + * name. + */ + bzero(&md, sizeof(md)); + strlcpy(md.md_magic, G_VIRSTOR_MAGIC, sizeof(md.md_magic)); + md.md_version = G_VIRSTOR_VERSION; + name = gctl_get_ascii(req, "arg0"); + if (name == NULL) { + gctl_error(req, "No 'arg%u' argument.", 0); + return; + } + strlcpy(md.md_name, name, sizeof(md.md_name)); + + md.md_virsize = (off_t)gctl_get_intmax(req, "vir_size"); + md.md_chunk_size = gctl_get_intmax(req, "chunk_size"); + md.md_count = nargs - 1; + + if (md.md_virsize == 0 || md.md_chunk_size == 0) { + gctl_error(req, "Virtual size and chunk size must be non-zero"); + return; + } + + msize = secsize = 0; + for (i = 1; i < (unsigned)nargs; i++) { + snprintf(param, sizeof(param), "arg%u", i); + name = gctl_get_ascii(req, "%s", param); + ssize = g_get_sectorsize(name); + if (ssize == 0) + fprintf(stderr, "%s for %s\n", strerror(errno), name); + msize += g_get_mediasize(name); + if (secsize == 0) + secsize = ssize; + else if (secsize != ssize) { + gctl_error(req, "Devices need to have same sector size " + "(%u on %s needs to be %u).", + (u_int)ssize, name, (u_int)secsize); + return; + } + } + + if (secsize == 0) { + gctl_error(req, "Device not specified"); + return; + } + + if (md.md_chunk_size % secsize != 0) { + size_t new_size = roundup(md.md_chunk_size, secsize); + fprintf(stderr, "Resizing chunk size to be a multiple of " + "sector size (%zu bytes).\n", secsize); + fprintf(stderr, "New chunk size: %zu kB\n", new_size / 1024); + md.md_chunk_size = new_size; + } + + if (md.md_virsize % md.md_chunk_size != 0) { + off_t chunk_count = md.md_virsize / md.md_chunk_size; + md.md_virsize = chunk_count * md.md_chunk_size; + fprintf(stderr, "Resizing virtual size to be a multiple of " + "chunk size.\n"); + fprintf(stderr, "New virtual size: %zu MB\n", + (size_t)(md.md_virsize / (1024 * 1024))); + } + + total_chunks = md.md_virsize / md.md_chunk_size; + map_size = total_chunks * sizeof(*map); + assert(md.md_virsize % md.md_chunk_size == 0); + + ssize = map_size % secsize; + if (ssize != 0) { + size_t add_chunks = (secsize - ssize) / sizeof(*map); + total_chunks += add_chunks; + md.md_virsize = (off_t)total_chunks * (off_t)md.md_chunk_size; + map_size = total_chunks * sizeof(*map); + fprintf(stderr, "Resizing virtual size to fit virstor " + "structures.\n"); + fprintf(stderr, "New virtual size: %ju MB (%zu new chunks)\n", + (uintmax_t)(md.md_virsize / (1024 * 1024)), add_chunks); + } + + if (verbose) + printf("Total virtual chunks: %zu (%zu MB each), %ju MB total " + "virtual size.\n", + total_chunks, (size_t)(md.md_chunk_size / (1024 * 1024)), + md.md_virsize/(1024 * 1024)); + + if ((off_t)md.md_virsize < msize) + fprintf(stderr, "WARNING: Virtual storage size < Physical " + "available storage (%ju < %ju)\n", md.md_virsize, msize); + + /* Clear last sector first to spoil all components if device exists. */ + if (verbose) + printf("Clearing metadata on"); + + for (i = 1; i < (unsigned)nargs; i++) { + snprintf(param, sizeof(param), "arg%u", i); + name = gctl_get_ascii(req, "%s", param); + + if (verbose) + printf(" %s", name); + + msize = g_get_mediasize(name); + ssize = g_get_sectorsize(name); + if (msize == 0 || ssize == 0) { + gctl_error(req, "Can't retrieve information about " + "%s: %s.", name, strerror(errno)); + return; + } + if (msize < (off_t) MAX(md.md_chunk_size*4, map_size)) + gctl_error(req, "Device %s is too small", name); + error = g_metadata_clear(name, NULL); + if (error != 0) { + gctl_error(req, "Can't clear metadata on %s: %s.", name, + strerror(error)); + return; + } + } + + + /* Write allocation table to the first provider - this needs to be done + * before metadata is written because when kernel tastes it it's too + * late */ + name = gctl_get_ascii(req, "arg1"); /* device with metadata */ + if (verbose) + printf(".\nWriting allocation table to %s...", name); + + /* How many chunks does the map occupy? */ + map_chunks = map_size/md.md_chunk_size; + if (map_size % md.md_chunk_size != 0) + map_chunks++; + if (verbose) { + printf(" (%zu MB, %d chunks) ", map_size/(1024*1024), map_chunks); + fflush(stdout); + } + + if (strncmp(name, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) + fd = open(name, O_RDWR); + else { + sprintf(param, "%s%s", _PATH_DEV, name); + fd = open(param, O_RDWR); + } + if (fd < 0) { + gctl_error(req, "Cannot open provider %s to write map", name); + return; + } + + /* + * Initialize and write the map. Don't malloc the whole map at once, + * in case it's large. Use calloc because there might be a need to set + * up chunk flags in the future. + */ + write_max_map_entries = 1024 * 1024 / sizeof(*map); + if (write_max_map_entries > total_chunks) + write_max_map_entries = total_chunks; + map = calloc(write_max_map_entries, sizeof(*map)); + if (map == NULL) { + gctl_error(req, + "Out of memory (need %zu bytes for allocation map)", + write_max_map_entries * sizeof(*map)); + close(fd); + return; + } + for (size_t chunk = 0; chunk < total_chunks; + chunk += write_max_map_entries) { + size_t bytes_to_write, entries_to_write; + + entries_to_write = total_chunks - chunk; + if (entries_to_write > write_max_map_entries) + entries_to_write = write_max_map_entries; + bytes_to_write = entries_to_write * sizeof(*map); + for (size_t off = 0; off < bytes_to_write; off += written) { + written = write(fd, ((char *)map) + off, + bytes_to_write - off); + if (written < 0) { + if (verbose) { + fprintf(stderr, + "\nError writing map at offset " + "%zu of %zu: %s\n", + chunk * sizeof(*map) + off, + map_size, strerror(errno)); + } + gctl_error(req, + "Error writing out allocation map!"); + free(map); + close(fd); + return; + } + } + } + free(map); + map = NULL; + close (fd); + + if (verbose) + printf("\nStoring metadata on "); + + /* + * ID is randomly generated, unique for a geom. This is used to + * recognize all providers belonging to one geom. + */ + md.md_id = arc4random(); + + /* Ok, store metadata. */ + for (i = 1; i < (unsigned)nargs; i++) { + snprintf(param, sizeof(param), "arg%u", i); + name = gctl_get_ascii(req, "%s", param); + + msize = g_get_mediasize(name); + ssize = g_get_sectorsize(name); + + if (verbose) + printf("%s ", name); + + /* this provider's position/type in geom */ + md.no = i - 1; + /* this provider's size */ + md.provsize = msize; + /* chunk allocation info */ + md.chunk_count = md.provsize / md.md_chunk_size; + if (verbose) + printf("(%u chunks) ", md.chunk_count); + /* Check to make sure last sector is unused */ + if ((off_t)(md.chunk_count * md.md_chunk_size) > (off_t)(msize-ssize)) + md.chunk_count--; + md.chunk_next = 0; + if (i != 1) { + md.chunk_reserved = 0; + md.flags = 0; + } else { + md.chunk_reserved = map_chunks * 2; + md.flags = VIRSTOR_PROVIDER_ALLOCATED | + VIRSTOR_PROVIDER_CURRENT; + md.chunk_next = md.chunk_reserved; + if (verbose) + printf("(%u reserved) ", md.chunk_reserved); + } + + if (!hardcode) + bzero(md.provider, sizeof(md.provider)); + else { + /* convert "/dev/something" to "something" */ + if (strncmp(name, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) { + strlcpy(md.provider, name + sizeof(_PATH_DEV) - 1, + sizeof(md.provider)); + } else + strlcpy(md.provider, name, sizeof(md.provider)); + } + sect = calloc(ssize, sizeof(unsigned char)); + if (sect == NULL) + err(1, "Cannot allocate sector of %zu bytes", ssize); + virstor_metadata_encode(&md, sect); + error = g_metadata_store(name, sect, ssize); + free(sect); + if (error != 0) { + if (verbose) + printf("\n"); + fprintf(stderr, "Can't store metadata on %s: %s.\n", + name, strerror(error)); + gctl_error(req, + "Not fully done (error storing metadata)."); + return; + } + } +#if 0 + if (verbose) + printf("\n"); +#endif +} + +/* Clears metadata on given provider(s) IF it's owned by us */ +static void +virstor_clear(struct gctl_req *req) +{ + const char *name; + char param[32]; + unsigned i; + int nargs, error; + int fd; + + nargs = gctl_get_int(req, "nargs"); + if (nargs < 1) { + gctl_error(req, "Too few arguments."); + return; + } + for (i = 0; i < (unsigned)nargs; i++) { + snprintf(param, sizeof(param), "arg%u", i); + name = gctl_get_ascii(req, "%s", param); + + error = g_metadata_clear(name, G_VIRSTOR_MAGIC); + if (error != 0) { + fprintf(stderr, "Can't clear metadata on %s: %s " + "(do I own it?)\n", name, strerror(error)); + gctl_error(req, + "Not fully done (can't clear metadata)."); + continue; + } + if (strncmp(name, _PATH_DEV, sizeof(_PATH_DEV) - 1) == 0) + fd = open(name, O_RDWR); + else { + sprintf(param, "%s%s", _PATH_DEV, name); + fd = open(param, O_RDWR); + } + if (fd < 0) { + gctl_error(req, "Cannot clear header sector for %s", + name); + continue; + } + if (verbose) + printf("Metadata cleared on %s.\n", name); + } +} + +/* Print some metadata information */ +static void +virstor_metadata_dump(const struct g_virstor_metadata *md) +{ + printf(" Magic string: %s\n", md->md_magic); + printf(" Metadata version: %u\n", (u_int) md->md_version); + printf(" Device name: %s\n", md->md_name); + printf(" Device ID: %u\n", (u_int) md->md_id); + printf(" Provider index: %u\n", (u_int) md->no); + printf(" Active providers: %u\n", (u_int) md->md_count); + printf(" Hardcoded provider: %s\n", + md->provider[0] != '\0' ? md->provider : "(not hardcoded)"); + printf(" Virtual size: %u MB\n", + (unsigned int)(md->md_virsize/(1024 * 1024))); + printf(" Chunk size: %u kB\n", md->md_chunk_size / 1024); + printf(" Chunks on provider: %u\n", md->chunk_count); + printf(" Chunks free: %u\n", md->chunk_count - md->chunk_next); + printf(" Reserved chunks: %u\n", md->chunk_reserved); +} + +/* Called by geom(8) via gvirstor_main() to dump metadata information */ +static void +virstor_dump(struct gctl_req *req) +{ + struct g_virstor_metadata md; + u_char tmpmd[512]; /* temporary buffer */ + const char *name; + char param[16]; + int nargs, error, i; + + assert(sizeof(tmpmd) >= sizeof(md)); + + nargs = gctl_get_int(req, "nargs"); + if (nargs < 1) { + gctl_error(req, "Too few arguments."); + return; + } + for (i = 0; i < nargs; i++) { + snprintf(param, sizeof(param), "arg%u", i); + name = gctl_get_ascii(req, "%s", param); + + error = g_metadata_read(name, (u_char *) & tmpmd, sizeof(tmpmd), + G_VIRSTOR_MAGIC); + if (error != 0) { + fprintf(stderr, "Can't read metadata from %s: %s.\n", + name, strerror(error)); + gctl_error(req, + "Not fully done (error reading metadata)."); + continue; + } + virstor_metadata_decode((u_char *) & tmpmd, &md); + printf("Metadata on %s:\n", name); + virstor_metadata_dump(&md); + printf("\n"); + } +} diff --git a/lib/geom/virstor/gvirstor.8 b/lib/geom/virstor/gvirstor.8 new file mode 100644 index 000000000000..436b60bef02c --- /dev/null +++ b/lib/geom/virstor/gvirstor.8 @@ -0,0 +1,297 @@ +.\" Copyright (c) 2006-2011 Ivan Voras <ivoras@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. +.\" +.Dd October 1, 2013 +.Dt GVIRSTOR 8 +.Os +.Sh NAME +.Nm gvirstor +.Nd "control utility for virtual data storage devices" +.Sh SYNOPSIS +.Nm +.Cm label +.Op Fl hv +.Op Fl s Ar virsize +.Op Fl m Ar chunksize +.Ar name +.Ar prov ... +.Nm +.Cm stop +.Op Fl fv +.Ar name ... +.Nm +.Cm destroy +.Op Fl fv +.Ar name ... +.Nm +.Cm add +.Op Fl vh +.Ar name prov ... +.Nm +.Cm remove +.Op Fl v +.Ar name prov ... +.Nm +.Cm clear +.Op Fl v +.Ar prov ... +.Nm +.Cm dump +.Ar prov ... +.Nm +.Cm list +.Nm +.Cm status +.Nm +.Cm load +.Nm +.Cm unload +.Sh DESCRIPTION +The +.Nm +utility is used for setting up a virtual storage device of arbitrary +large size +.Pq for example, several TB , +consisting of an arbitrary number of physical storage devices with the +total size which is equal to or smaller than the virtual size. +Data for the virtual devices will be allocated from physical devices on +demand. +The idea behind +.Nm +is similar to the concept of Virtual Memory in operating systems, +effectively allowing users to overcommit on storage +.Pq free file system space . +The concept is also known as "thin provisioning" in virtualization +environments, only here it is implemented on the level of physical storage +devices. +.Pp +The first argument to +.Nm +indicates an action to be performed: +.Bl -tag -width ".Cm remove" +.It Cm label +Set up a virtual device from the given components with the specified +.Ar name . +Metadata is stored in the last sector of every component. +Argument +.Fl s Ar virsize +is the size of new virtual device, with default being set to 2 TiB +.Pq 2097152 MiB . +Argument +.Fl m Ar chunksize +is the chunk size, with default being set to 4 MiB +.Pq 4096 KiB . +The default arguments are thus +.Qq Fl s Ar 2097152 Fl m Ar 4096 . +.It Cm stop +Turn off an existing virtual device with the given +.Ar name . +This command does not touch on-disk metadata. +As with other GEOM classes, stopped geoms cannot be started manually. +.It Cm destroy +Same as +.Cm stop. +.It Cm add +Adds new components to existing virtual device with the given +.Ar name . +The specified virstor device must exist and be active +.Pq i.e. module loaded, device present in Pa /dev . +This action can be safely performed while the virstor device is in use +.Pq Qo hot Qc operation . +.It Cm remove +Removes components from existing virtual device with the given +.Ar name . +Only unallocated providers can be removed. +.It Cm clear +Clear metadata on the given providers. +.It Cm dump +Dump metadata stored on the given providers. +.It Cm list +See +.Xr geom 8 . +.It Cm status +See +.Xr geom 8 . +.It Cm load +See +.Xr geom 8 . +.It Cm unload +See +.Xr geom 8 . +.El +.Pp +Additional options: +.Bl -tag -width ".Fl f" +.It Fl f +Force the removal of the specified virtual device. +.It Fl h +Hardcode providers' names in metadata. +.It Fl v +Be more verbose. +.El +.Sh EXAMPLES +The following example shows how to create a virtual device of default size +.Pq 2 TiB , +of default chunk +.Pq extent +size +.Pq 4 MiB , +with two physical devices for backing storage. +.Bd -literal -offset indent +.No gvirstor label -v Ar mydata Ar /dev/ada4 Ar /dev/ada6 +.No newfs Ar /dev/virstor/mydata +.Ed +.Pp +From now on, the virtual device will be available via the +.Pa /dev/virstor/mydata +device entry. +To add a new physical device / component to an active virstor device: +.Bd -literal -offset indent +.No gvirstor add Ar mydata Ar ada8 +.Ed +.Pp +This will add physical storage of +.Ar ada8 +to +.Pa /dev/virstor/mydata +device. +.Pp +To see the device status information +.Pq including how much physical storage is still available for the virtual device , +use: +.Bd -literal -offset indent +gvirstor list +.Ed +.Pp +All standard +.Xr geom 8 +subcommands +.Pq e.g. Cm status , Cm help +are also supported. +.Sh SYSCTL VARIABLES +.Nm +has several +.Xr sysctl 8 +tunable variables. +.Bd -literal -offset indent +.Va int kern.geom.virstor.debug +.Ed +.Pp +This sysctl controls verbosity of the kernel module, in the range +1 to 15. +Messages that are marked with higher verbosity levels than this are +suppressed. +Default value is 5 and it is not recommended to set this tunable to less +than 2, because level 1 messages are error events, and level 2 messages +are system warnings. +.Bd -literal -offset indent +.Va int kern.geom.virstor.chunk_watermark +.Ed +.Pp +Value in this sysctl sets warning watermark level for physical chunk +usage on a single component. +The warning is issued when a virstor component has less than this many +free chunks +.Pq default 100 . +.Bd -literal -offset indent +.Va int kern.geom.virstor.component_watermark +.Ed +.Pp +Value in this sysctl sets warning watermark level for component usage. +The warning is issued when there are less than this many unallocated +components +.Pq default is 1 . +.Pp +All these sysctls are also available as +.Xr loader 8 +tunables. +.Sh DIAGNOSTICS +.Ex -std +.Pp +.Nm +kernel module issues log messages with prefixes in standardized format, +which is useful for log message filtering and dispatching. +Each message line begins with +.Bd -literal -offset indent +.Li GEOM_VIRSTOR[%d]: +.Ed +.Pp +The number +.Pq %d +is message verbosity / importance level, in the range 1 to 15. +If a message filtering, dispatching or operator alert system is used, it +is recommended that messages with levels 1 and 2 be taken seriously +.Pq for example, to catch out-of-space conditions as set by watermark +sysctls. +.Sh SEE ALSO +.Xr geom 4 , +.Xr fstab 5 , +.Xr geom 8 , +.Xr glabel 8 , +.Xr newfs 8 +.Sh HISTORY +The +.Nm +utility first appeared in +.Fx 7.0 . +.Sh AUTHORS +.An Ivan Voras Aq Mt ivoras@FreeBSD.org +.Pp +Sponsored by Google Summer of Code 2006. +.Sh BUGS +Commands +.Cm add +and +.Cm remove +contain unavoidable critical sections which may make the virstor +device unusable if a power failure +.Pq or other disruptive event +happens during their execution. +It is recommended to run them when the system is quiescent. +.Sh ASSUMPTIONS AND INTERACTION WITH FILE SYSTEMS +There are several assumptions that +.Nm +has in its operation: that the size of the virtual storage device will not +change once it is set, and that the sizes of individual physical storage +components will always remain constant during their existence. +For alternative ways to implement virtual or resizable file systems see +.Xr zfs 1M , +.Xr gconcat 8 +and +.Xr growfs 8 . +.Pp +Note that +.Nm +has nontrivial interaction with file systems which initialize a large +number of on-disk structures during newfs. +If such file systems attempt to spread their structures across the drive +media +.Pq like UFS/UFS2 does , +their efforts will be effectively foiled by sequential allocation of +chunks in +.Nm +and all their structures will be physically allocated at the start +of the first virstor component. +This could have a significant impact on file system performance +.Pq which can in some rare cases be even positive . |