Update heuristic used for default and detected data alignment.

Add "devices/default_data_alignment" to lvm.conf to control the internal
default that LVM2 uses: 0==64k, 1==1MB, 2==2MB, etc.

If --dataalignment (or lvm.conf's "devices/data_alignment") is specified
then it is always used to align the start of the data area.  This means
the md_chunk_alignment and data_alignment_detection are disabled if set.

(Same now applies to pvcreate --dataalignmentoffset, the specified value
will be used instead of the result from data_alignment_offset_detection)

set_pe_align() still looks to use the determined default alignment
(based on lvm.conf's default_data_alignment) if the default is a
multiple of the MD or topology detected values.

diff --git a/WHATS_NEW b/WHATS_NEW
index 8a1085ed359fb7d6d6e4f0809d0a63cf7645c22d..48145495bd9be7195e5079a5aac0afb57e8e38fe 100644 (file)
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,7 @@
 Version 2.02.74 - 
 ==================================
+  Update heuristic used for default and detected data alignment.
+  Add "devices/default_data_alignment" to lvm.conf.
   Add implmentation for simple numeric 'get' property functions.
   Define GET_NUM_PROPERTY_FN macro to simplify numeric property 'get' function
   Add properties.[ch] to lib/report, defined based on columns.h.

diff --git a/doc/example.conf.in b/doc/example.conf.in
index 7edae715387586e2bffc22e70b0537b0453de96a..6c75f8c98644159bec9aa082b93e1b77a5af075c 100644 (file)
--- a/doc/example.conf.in
+++ b/doc/example.conf.in
@@ -98,6 +98,11 @@ devices {
     # 1 enables; 0 disables.
     md_chunk_alignment = 1
 
+    # Default alignment of the start of a data area in MB.  If set to 0,
+    # a small value of 64KB will be used, which was the default until
+    # LVM2 version 2.02.73.  Set to 1 for 1MiB, 2 for 2MiB, etc.
+    default_data_alignment = 1
+
     # By default, the start of a PV's data area will be a multiple of
     # the 'minimum_io_size' or 'optimal_io_size' exposed in sysfs.
     # - minimum_io_size - the smallest request the device can perform
@@ -111,9 +116,9 @@ devices {
     data_alignment_detection = 1
 
     # Alignment (in KB) of start of data area when creating a new PV.
-    # If a PV is placed directly upon an md device and md_chunk_alignment or
-    # data_alignment_detection is enabled this parameter is ignored.
-    # Set to 0 for the default alignment of 1MB or page size, if larger.
+    # md_chunk_alignment and data_alignment_detection are disabled if set.
+    # Set to 0 for the default alignment (see: data_alignment_default)
+    # or page size, if larger.
     data_alignment = 0
 
     # By default, the start of the PV's aligned data area will be shifted by
@@ -122,6 +127,7 @@ devices {
     # windows partitioning will have an alignment_offset of 3584 bytes
     # (sector 7 is the lowest aligned logical block, the 4KB sectors start
     # at LBA -1, and consequently sector 63 is aligned on a 4KB boundary).
+    # But note that pvcreate --dataalignmentoffset will skip this detection.
     # 1 enables; 0 disables.
     data_alignment_offset_detection = 1
 

diff --git a/lib/config/defaults.h b/lib/config/defaults.h
index b6308f45439b1fbb2aabae6f1634296c8f1545b4..d9c9e3b28d62bfcf68ea59597bc9a729d16173c9 100644 (file)
--- a/lib/config/defaults.h
+++ b/lib/config/defaults.h
@@ -17,6 +17,7 @@
 #define _LVM_DEFAULTS_H
 
 #define DEFAULT_PE_ALIGN 2048
+#define DEFAULT_PE_ALIGN_OLD 128
 
 #define DEFAULT_ARCHIVE_ENABLED 1
 #define DEFAULT_BACKUP_ENABLED 1
@@ -33,6 +34,7 @@
 #define DEFAULT_MD_CHUNK_ALIGNMENT 1
 #define DEFAULT_IGNORE_SUSPENDED_DEVICES 1
 #define DEFAULT_REQUIRE_RESTOREFILE_WITH_UUID 1
+#define DEFAULT_DATA_ALIGNMENT 1
 #define DEFAULT_DATA_ALIGNMENT_OFFSET_DETECTION 1
 #define DEFAULT_DATA_ALIGNMENT_DETECTION 1
 

diff --git a/lib/format_text/format-text.c b/lib/format_text/format-text.c
index c8cf89a132ab53c021a8b6dee1918580e2420bb8..db5af2a1a467a7bbad26118a53973eff085843d7 100644 (file)
--- a/lib/format_text/format-text.c
+++ b/lib/format_text/format-text.c
@@ -1861,16 +1861,20 @@ static int _text_pv_setup(const struct format_type *fmt,
                                                      0) * 2;
 
                if (set_pe_align(pv, data_alignment) != data_alignment &&
-                   data_alignment)
-                       log_warn("WARNING: %s: Overriding data alignment to "
-                                "%lu sectors (requested %lu sectors)",
-                                pv_dev_name(pv), pv->pe_align, data_alignment);
+                   data_alignment) {
+                       log_error("%s: invalid data alignment of "
+                                 "%lu sectors (requested %lu sectors)",
+                                 pv_dev_name(pv), pv->pe_align, data_alignment);
+                       return 0;
+               }
 
                if (set_pe_align_offset(pv, data_alignment_offset) != data_alignment_offset &&
-                   data_alignment_offset)
-                       log_warn("WARNING: %s: Overriding data alignment offset to "
-                                "%lu sectors (requested %lu sectors)",
-                                pv_dev_name(pv), pv->pe_align_offset, data_alignment_offset);
+                   data_alignment_offset) {
+                       log_error("%s: invalid data alignment offset of "
+                                 "%lu sectors (requested %lu sectors)",
+                                 pv_dev_name(pv), pv->pe_align_offset, data_alignment_offset);
+                       return 0;
+               }
 
                if (pv->pe_align < pv->pe_align_offset) {
                        log_error("%s: pe_align (%lu sectors) must not be less "

diff --git a/lib/metadata/metadata.c b/lib/metadata/metadata.c
index 2a3d03695a5c0b8192bed83395c6247fb98c08b4..d14c33c74609e889ddf51c36d16317e8d2f46622 100644 (file)
--- a/lib/metadata/metadata.c
+++ b/lib/metadata/metadata.c
@@ -62,23 +62,38 @@ static uint32_t _vg_bad_status_bits(const struct volume_group *vg,
 const char _really_init[] =
     "Really INITIALIZE physical volume \"%s\" of volume group \"%s\" [y/n]? ";
 
-static int _alignment_overrides_default(unsigned long data_alignment)
+static int _alignment_overrides_default(unsigned long data_alignment,
+                                       unsigned long default_pe_align)
 {
-       return data_alignment && (DEFAULT_PE_ALIGN % data_alignment);
+       return data_alignment && (default_pe_align % data_alignment);
 }
 
 unsigned long set_pe_align(struct physical_volume *pv, unsigned long data_alignment)
 {
-       unsigned long temp_pe_align;
+       unsigned long default_pe_align, temp_pe_align;
 
        if (pv->pe_align)
                goto out;
 
-       if (data_alignment)
+       if (data_alignment) {
+               /* Always use specified data_alignment */
                pv->pe_align = data_alignment;
+               goto out;
+       }
+
+       default_pe_align = find_config_tree_int(pv->fmt->cmd,
+                                               "devices/default_data_alignment",
+                                               DEFAULT_DATA_ALIGNMENT);
+
+       if (default_pe_align)
+               /* align on 1 MiB multiple */
+               default_pe_align *= DEFAULT_PE_ALIGN;
        else
-               pv->pe_align = MAX((DEFAULT_PE_ALIGN << SECTOR_SHIFT),
-                                  lvm_getpagesize()) >> SECTOR_SHIFT;
+               /* align on 64 KiB multiple (old default) */
+               default_pe_align = DEFAULT_PE_ALIGN_OLD;
+
+       pv->pe_align = MAX((default_pe_align << SECTOR_SHIFT),
+                          lvm_getpagesize()) >> SECTOR_SHIFT;
 
        if (!pv->dev)
                goto out;
@@ -89,8 +104,8 @@ unsigned long set_pe_align(struct physical_volume *pv, unsigned long data_alignm
        if (find_config_tree_bool(pv->fmt->cmd, "devices/md_chunk_alignment",
                                  DEFAULT_MD_CHUNK_ALIGNMENT)) {
                temp_pe_align = dev_md_stripe_width(pv->fmt->cmd->sysfs_dir, pv->dev);
-               if (_alignment_overrides_default(temp_pe_align))
-                       pv->pe_align = temp_pe_align;
+               if (_alignment_overrides_default(temp_pe_align, default_pe_align))
+                       pv->pe_align = MAX(pv->pe_align, temp_pe_align);
        }
 
        /*
@@ -104,18 +119,18 @@ unsigned long set_pe_align(struct physical_volume *pv, unsigned long data_alignm
                                  "devices/data_alignment_detection",
                                  DEFAULT_DATA_ALIGNMENT_DETECTION)) {
                temp_pe_align = dev_minimum_io_size(pv->fmt->cmd->sysfs_dir, pv->dev);
-               if (_alignment_overrides_default(temp_pe_align))
-                       pv->pe_align = temp_pe_align;
+               if (_alignment_overrides_default(temp_pe_align, default_pe_align))
+                       pv->pe_align = MAX(pv->pe_align, temp_pe_align);
 
                temp_pe_align = dev_optimal_io_size(pv->fmt->cmd->sysfs_dir, pv->dev);
-               if (_alignment_overrides_default(temp_pe_align))
-                       pv->pe_align = temp_pe_align;
+               if (_alignment_overrides_default(temp_pe_align, default_pe_align))
+                       pv->pe_align = MAX(pv->pe_align, temp_pe_align);
        }
 
+out:
        log_very_verbose("%s: Setting PE alignment to %lu sectors.",
                         dev_name(pv->dev), pv->pe_align);
 
-out:
        return pv->pe_align;
 }
 
@@ -125,8 +140,11 @@ unsigned long set_pe_align_offset(struct physical_volume *pv,
        if (pv->pe_align_offset)
                goto out;
 
-       if (data_alignment_offset)
+       if (data_alignment_offset) {
+               /* Always use specified data_alignment_offset */
                pv->pe_align_offset = data_alignment_offset;
+               goto out;
+       }
 
        if (!pv->dev)
                goto out;
@@ -142,10 +160,10 @@ unsigned long set_pe_align_offset(struct physical_volume *pv,
                pv->pe_align_offset = MAX(pv->pe_align_offset, align_offset);
        }
 
+out:
        log_very_verbose("%s: Setting PE alignment offset to %lu sectors.",
                         dev_name(pv->dev), pv->pe_align_offset);
 
-out:
        return pv->pe_align_offset;
 }