Lines Matching full:group

6 The layout of a standard block group is approximately as follows (each
13    * - Group 0 Padding
15      - Group Descriptors
30 For the special case of block group 0, the first 1024 bytes are unused,
37 The ext4 driver primarily works with the superblock and the group
38 descriptors that are found in block group 0. Redundant copies of the
39 superblock and group descriptors are written to some of the block groups
42 paragraph for more details). If the group does not have a redundant
43 copy, the block group begins with the data block bitmap. Note also that
45 GDT block” space after the block group descriptors and before the start
54 As for the ordering of items in a block group, it is generally
55 established that the super block and the group descriptor table, if
56 present, will be at the beginning of the block group. The bitmaps and
67 logical block group; the bitmap spaces and the inode table space in the
68 first block group of the flex_bg are expanded to include the bitmaps
70 if the flex_bg size is 4, then group 0 will contain (in order) the
71 superblock, group descriptors, data block bitmaps for groups 0-3, inode
73 space in group 0 is for file data. The effect of this is to group the
74 block group metadata close together for faster loading, and to enable
76 and group descriptors are always at the beginning of block groups, even
83 Without the option META_BG, for safety concerns, all block group
84 descriptors copies are kept in the first block group. Given the default
85 128MiB(2^27 bytes) block group size and 64-byte group descriptors, ext4
89 The solution to this problem is to use the metablock group feature
92 groups. Each metablock group is a cluster of block groups whose group
94 filesystems with 4 KB block size, a single metablock group partition
95 includes 64 block groups, or 8 GiB of disk space. The metablock group
96 feature moves the location of the group descriptors from the congested
97 first block group of the whole filesystem into the first group of each
98 metablock group itself. The backups are in the second and last group of
99 each metablock group. This increases the 2^21 maximum block groups limit
103 the superblock is followed by a variable-length set of block group
104 descriptors. Instead, the superblock and a single block group descriptor
106 groups in a meta-block group. A meta-block group is a collection of
107 block groups which can be described by a single block group descriptor
108 block. Since the size of the block group descriptor structure is 64
109 bytes, a meta-block group contains 16 block groups for filesystems with
111 blocksize. Filesystems can either be created using this new block group
114 block group using this new layout.
119 Lazy Block Group Initialization
122 A new feature for ext4 are three block group descriptor flags that
123 enable mkfs to skip initializing other parts of the block group
125 that the inode and block bitmaps for that group can be calculated and
127 generally the case for an empty block group or a block group containing
128 only fixed-location block group metadata. The INODE_ZEROED flag means