Neil,
I've changed the tunables to the way we discussed. If it becomes
necessary to have the freedom to have simultaneous near and far copies,
then I will likely add 'raid10_near|far|offset_copies' to compliment the
existing 'raid10_copies' arg. Like you, I doubt they will be necessary
though.
I have yet to add the code that allows new devices to replace old/failed
devices (i.e. handles the 'rebuild' parameter). That will be a future
patch.
brassow
dm raid: add md raid10 support
Support the MD RAID10 personality through dm-raid.c
Signed-off-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Index: linux-upstream/drivers/md/dm-raid.c
===================================================================
--- linux-upstream.orig/drivers/md/dm-raid.c
+++ linux-upstream/drivers/md/dm-raid.c
@@ -11,6 +11,7 @@
#include "md.h"
#include "raid1.h"
#include "raid5.h"
+#include "raid10.h"
#include "bitmap.h"
#include <linux/device-mapper.h>
@@ -52,7 +53,10 @@ struct raid_dev {
#define DMPF_MAX_RECOVERY_RATE 0x20
#define DMPF_MAX_WRITE_BEHIND 0x40
#define DMPF_STRIPE_CACHE 0x80
-#define DMPF_REGION_SIZE 0X100
+#define DMPF_REGION_SIZE 0x100
+#define DMPF_RAID10_COPIES 0x200
+#define DMPF_RAID10_FORMAT 0x400
+
struct raid_set {
struct dm_target *ti;
@@ -76,6 +80,7 @@ static struct raid_type {
const unsigned algorithm; /* RAID algorithm. */
} raid_types[] = {
{"raid1", "RAID1 (mirroring)", 0, 2, 1, 0 /* NONE */},
+ {"raid10", "RAID10 (striped mirrors)", 0, 2, 10, -1 /* Varies */},
{"raid4", "RAID4 (dedicated parity disk)", 1, 2, 5, ALGORITHM_PARITY_0},
{"raid5_la", "RAID5 (left asymmetric)", 1, 2, 5, ALGORITHM_LEFT_ASYMMETRIC},
{"raid5_ra", "RAID5 (right asymmetric)", 1, 2, 5, ALGORITHM_RIGHT_ASYMMETRIC},
@@ -86,6 +91,36 @@ static struct raid_type {
{"raid6_nc", "RAID6 (N continue)", 2, 4, 6, ALGORITHM_ROTATING_N_CONTINUE}
};
+static char *raid10_md_layout_to_format(int layout)
+{
+ if (layout & 0x10000)
+ return "offset";
+
+ if ((layout & 0xFF) > 1)
+ return "near";
+
+ return "far";
+}
+
+static unsigned raid10_md_layout_to_copies(int layout)
+{
+ if ((layout & 0xFF) > 1)
+ return layout & 0xFF;
+ return (layout >> 8) & 0xFF;
+}
+
+static int raid10_format_to_md_layout(char *format, unsigned copies)
+{
+ unsigned n = 1, f = 1;
+
+ if (!strcmp("near", format))
+ n = copies;
+ else
+ f = copies;
+
+ return (!strcmp("offset", format) << 16) | (f << 8) | n;
+}
+
static struct raid_type *get_raid_type(char *name)
{
int i;
@@ -339,10 +374,16 @@ static int validate_region_size(struct r
* [max_write_behind <sectors>] See '-write-behind=' (man mdadm)
* [stripe_cache <sectors>] Stripe cache size for higher RAIDs
* [region_size <sectors>] Defines granularity of bitmap
+ *
+ * RAID10-only options:
+ * [raid10_copies <# copies>] Number of copies. (Default: 2)
+ * [raid10_format <near|far|offset>] Layout algorithm. (Default: near)
*/
static int parse_raid_params(struct raid_set *rs, char **argv,
unsigned num_raid_params)
{
+ char *raid10_format = "near";
+ unsigned raid10_copies = 2;
unsigned i, rebuild_cnt = 0;
unsigned long value, region_size = 0;
sector_t sectors_per_dev = rs->ti->len;
@@ -416,11 +457,30 @@ static int parse_raid_params(struct raid
}
key = argv[i++];
+
+ /* Parameters that take a string value are checked here. */
+ if (!strcasecmp(key, "raid10_format")) {
+ if (rs->raid_type->level != 10) {
+ rs->ti->error = "'raid10_format' is an invalid parameter for this RAID type";
+ return -EINVAL;
+ }
+ if (strcmp("near", argv[i]) &&
+ strcmp("far", argv[i]) &&
+ strcmp("offset", argv[i])) {
+ rs->ti->error = "Invalid 'raid10_format' value given";
+ return -EINVAL;
+ }
+ raid10_format = argv[i];
+ rs->print_flags |= DMPF_RAID10_FORMAT;
+ continue;
+ }
+
if (strict_strtoul(argv[i], 10, &value) < 0) {
rs->ti->error = "Bad numerical argument given in raid params";
return -EINVAL;
}
+ /* Parameters that take a numeric value are checked here */
if (!strcasecmp(key, "rebuild")) {
rebuild_cnt++;
rs->ti->error = NULL;
@@ -436,6 +496,7 @@ static int parse_raid_params(struct raid
if (rebuild_cnt > rs->raid_type->parity_devs)
rs->ti->error = "Too many rebuild devices specified for given RAID type";
break;
+ case 10:
default:
DMERR("The rebuild parameter is not supported for %s", rs->raid_type->name);
rs->ti->error = "Rebuild not supported for this RAID type";
@@ -493,7 +554,7 @@ static int parse_raid_params(struct raid
*/
value /= 2;
- if (rs->raid_type->level < 5) {
+ if (rs->raid_type->level != 5) {
rs->ti->error = "Inappropriate argument: stripe_cache";
return -EINVAL;
}
@@ -518,6 +579,14 @@ static int parse_raid_params(struct raid
} else if (!strcasecmp(key, "region_size")) {
rs->print_flags |= DMPF_REGION_SIZE;
region_size = value;
+ } else if (!strcasecmp(key, "raid10_copies") &&
+ (rs->raid_type->level == 10)) {
+ if ((value < 2) || (value > 0xFF)) {
+ rs->ti->error = "Bad value for 'raid10_copies'";
+ return -EINVAL;
+ }
+ rs->print_flags |= DMPF_RAID10_COPIES;
+ raid10_copies = value;
} else {
DMERR("Unable to parse RAID parameter: %s", key);
rs->ti->error = "Unable to parse RAID parameters";
@@ -536,9 +605,25 @@ static int parse_raid_params(struct raid
if (dm_set_target_max_io_len(rs->ti, max_io_len))
return -EINVAL;
- if ((rs->raid_type->level > 1) &&
- sector_div(sectors_per_dev, (rs->md.raid_disks - rs->raid_type->parity_devs))) {
+ if (rs->raid_type->level == 10) {
+ /* (Len * Stripes) / Mirrors */
+ sectors_per_dev *= rs->md.raid_disks;
+ if (sector_div(sectors_per_dev, raid10_copies)) {
+ rs->ti->error = "Target length not divisible by number of data devices";
+ return -EINVAL;
+ }
+ if (raid10_copies > rs->md.raid_disks) {
+ rs->ti->error = "Not enough devices to satisfy specification";
+ return -EINVAL;
+ }
+ rs->md.layout = raid10_format_to_md_layout(raid10_format,
+ raid10_copies);
+ rs->md.new_layout = rs->md.layout;
+ } else if ((rs->raid_type->level > 1) &&
+ sector_div(sectors_per_dev,
+ (rs->md.raid_disks - rs->raid_type->parity_devs))) {
rs->ti->error = "Target length not divisible by number of data devices";
+
return -EINVAL;
}
rs->md.dev_sectors = sectors_per_dev;
@@ -564,6 +649,9 @@ static int raid_is_congested(struct dm_t
if (rs->raid_type->level == 1)
return md_raid1_congested(&rs->md, bits);
+ if (rs->raid_type->level == 10)
+ return md_raid10_congested(&rs->md, bits);
+
return md_raid5_congested(&rs->md, bits);
}
@@ -882,6 +970,9 @@ static int analyse_superblocks(struct dm
case 6:
redundancy = rs->raid_type->parity_devs;
break;
+ case 10:
+ redundancy = raid10_md_layout_to_copies(mddev->layout) - 1;
+ break;
default:
ti->error = "Unknown RAID type";
return -EINVAL;
@@ -1201,6 +1292,14 @@ static int raid_status(struct dm_target
DMEMIT(" region_size %lu",
rs->md.bitmap_info.chunksize >> 9);
+ if (rs->print_flags & DMPF_RAID10_COPIES)
+ DMEMIT(" raid10_copies %u",
+ raid10_md_layout_to_copies(rs->md.layout));
+
+ if (rs->print_flags & DMPF_RAID10_FORMAT)
+ DMEMIT(" raid10_format %s",
+ raid10_md_layout_to_format(rs->md.layout));
+
DMEMIT(" %d", rs->md.raid_disks);
for (i = 0; i < rs->md.raid_disks; i++) {
if (rs->dev[i].meta_dev)
@@ -1275,7 +1374,7 @@ static void raid_resume(struct dm_target
static struct target_type raid_target = {
.name = "raid",
- .version = {1, 2, 0},
+ .version = {1, 3, 0},
.module = THIS_MODULE,
.ctr = raid_ctr,
.dtr = raid_dtr,
@@ -1302,6 +1401,8 @@ module_init(dm_raid_init);
module_exit(dm_raid_exit);
MODULE_DESCRIPTION(DM_NAME " raid4/5/6 target");
+MODULE_ALIAS("dm-raid1");
+MODULE_ALIAS("dm-raid10");
MODULE_ALIAS("dm-raid4");
MODULE_ALIAS("dm-raid5");
MODULE_ALIAS("dm-raid6");
Index: linux-upstream/Documentation/device-mapper/dm-raid.txt
===================================================================
--- linux-upstream.orig/Documentation/device-mapper/dm-raid.txt
+++ linux-upstream/Documentation/device-mapper/dm-raid.txt
@@ -27,6 +27,11 @@ The target is named "raid" and it accept
- rotating parity N (right-to-left) with data restart
raid6_nc RAID6 N continue
- rotating parity N (right-to-left) with data continuation
+ raid10 Various RAID10 inspired algorithms chosen by additional params
+ - RAID10: Striped Mirrors (aka 'Striping on top of mirrors')
+ - RAID1E: Integrated Adjacent Stripe Mirroring
+ - RAID1E: Integrated Offset Stripe Mirroring
+ - and other similar RAID10 variants
Reference: Chapter 4 of
http://www.snia.org/sites/default/files/SNIA_DDF_Technical_Position_v2.0.pdf
@@ -59,6 +64,59 @@ The target is named "raid" and it accept
logical size of the array. The bitmap records the device
synchronisation state for each region.
+ [raid10_copies <# copies>]
+ [raid10_format <near|far|offset>]
+ These two options are used to alter the default layout of
+ a RAID10 configuration. The number of copies is can be
+ specified, but the default is 2. There are also three
+ variations to how the copies are laid down - the default
+ is "near". Near copies are what most people think of with
+ respect to mirroring. If these options are left unspecified,
+ or 'raid10_copies 2' and/or 'raid10_format near' are given,
+ then the layouts for 2, 3 and 4 devices are:
+ 2 drives 3 drives 4 drives
+ -------- ---------- --------------
+ A1 A1 A1 A1 A2 A1 A1 A2 A2
+ A2 A2 A2 A3 A3 A3 A3 A4 A4
+ A3 A3 A4 A4 A5 A5 A5 A6 A6
+ A4 A4 A5 A6 A6 A7 A7 A8 A8
+ .. .. .. .. .. .. .. .. ..
+ The 2-device layout is equivalent 2-way RAID1. The 4-device
+ layout is what a traditional RAID10 would look like. The
+ 3-device layout is what might be called a 'RAID1E - Integrated
+ Adjacent Stripe Mirroring'.
+
+ If 'raid10_copies 2' and 'raid10_format far', then the layouts
+ for 2, 3 and 4 devices are:
+ 2 drives 3 drives 4 drives
+ -------- -------------- --------------------
+ A1 A2 A1 A2 A3 A1 A2 A3 A4
+ A3 A4 A4 A5 A6 A5 A6 A7 A8
+ A5 A6 A7 A8 A9 A9 A10 A11 A12
+ .. .. .. .. .. .. .. .. ..
+ A2 A1 A3 A1 A2 A4 A1 A2 A3
+ A4 A3 A6 A4 A5 A8 A5 A6 A7
+ A6 A5 A9 A7 A8 A12 A9 A10 A11
+ .. .. .. .. .. .. .. .. ..
+
+ If 'raid10_copies 2' and 'raid10_format offset', then the
+ layouts for 2, 3 and 4 devices are:
+ 2 drives 3 drives 4 drives
+ -------- ------------ -----------------
+ A1 A2 A1 A2 A3 A1 A2 A3 A4
+ A2 A1 A3 A1 A2 A4 A1 A2 A3
+ A3 A4 A4 A5 A6 A5 A6 A7 A8
+ A4 A3 A6 A4 A5 A8 A5 A6 A7
+ A5 A6 A7 A8 A9 A9 A10 A11 A12
+ A6 A5 A9 A7 A8 A12 A9 A10 A11
+ .. .. .. .. .. .. .. .. ..
+ Here we see layouts closely akin to 'RAID1E - Integrated
+ Offset Stripe Mirroring'.
+
+ Thanks wikipedia 'Non-standard RAID levels' for the layout
+ figures:
+ http://en.wikipedia.org/wiki/Non-standard_RAID_levels
+
<#raid_devs>: The number of devices composing the array.
Each device consists of two entries. The first is the device
containing the metadata (if any); the second is the one containing the
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
