On 29/07/2021 19.59, Theodore Ts'o wrote:

On Wed, Jul 28, 2021 at 11:36:27AM +0200, Mikhail Morfikov wrote:

quoted

Thanks for the answer.

I have one question. Basically there's the /etc/mke2fs.conf file and 
I've created the following stanza in it:

bigdata = {
                errors = remount-ro
                features = has_journal,extent,huge_file,flex_bg,metadata_csum,64bit,dir_nlink,extra_isize,bigalloc,^uninit_bg,sparse_super2
                inode_size = 256
                inode_ratio = 4194304
                cluster_size = 4M
                reserved_ratio = 0
                lazy_itable_init = 0
                lazy_journal_init = 0
        }

It looks like the cluster_size parameter is ignored in such case (I've 
tried both 4M and 4194304 values), and the filesystem was created with 
64K cluster size (via mkfs -t bigdata -L bigdata /dev/sdb1 ), which is 
the default when the bigalloc feature is set.

It does work, but you need to use an integer value for cluster_size,
and it needs to be in the [fs_types[ section.  So something like what I
have attached below.

And then try using the command "mke2fs -t ext4 -T bigdata -L bigdata
/dev/sdb1".

Yes, this helped and the cluster size was set to 4194304 as it should.

If you see the hugefile and hugefiles stanzas below, that's an example
of one way bigalloc has gotten a fair amount of use.  In this use case
mke2fs has pre-allocated the huge data files guaranteeing that they
will be 100% contiguous.  We're using a 32k cluster becuase there are
some metadata files where better allocation efficiencies is desired.

I'll try them both and see whether I could use either one of them on 
my drive.

Cheers,

						- Ted

[defaults]
	base_features = sparse_super,large_file,filetype,resize_inode,dir_index,ext_attr
	default_mntopts = acl,user_xattr
	enable_periodic_fsck = 0
	blocksize = 4096
	inode_size = 256
	inode_ratio = 16384
	undo_dir = /var/lib/e2fsprogs/undo

[fs_types]
	ext3 = {
		features = has_journal
	}
	ext4 = {
		features = has_journal,extent,huge_file,flex_bg,metadata_csum,64bit,dir_nlink,extra_isize
		inode_size = 256
	}
	small = {
		blocksize = 1024
		inode_size = 128
		inode_ratio = 4096
	}
	floppy = {
		blocksize = 1024
		inode_size = 128
		inode_ratio = 8192
	}
	big = {
		inode_ratio = 32768
	}
	huge = {
		inode_ratio = 65536
	}
	news = {
		inode_ratio = 4096
	}
	largefile = {
		inode_ratio = 1048576
		blocksize = -1
	}
	largefile4 = {
		inode_ratio = 4194304
		blocksize = -1
	}
	hurd = {
	     blocksize = 4096
	     inode_size = 128
	}
	hugefiles = {
		features = extent,huge_file,flex_bg,uninit_bg,dir_nlink,extra_isize,^resize_inode,sparse_super2
		hash_alg = half_md4
		reserved_ratio = 0.0
		num_backup_sb = 0
		packed_meta_blocks = 1
		make_hugefiles = 1
		inode_ratio = 4194304
		hugefiles_dir = /storage
		hugefiles_name = chunk-
		hugefiles_digits = 5
		hugefiles_size = 4G
		hugefiles_align = 256M
		hugefiles_align_disk = true
		zero_hugefiles = false
		flex_bg_size = 262144
	}

	hugefile = {
		features = extent,huge_file,bigalloc,flex_bg,uninit_bg,dir_nlink,extra_isize,^resize_inode,sparse_super2
		cluster_size = 32768
		hash_alg = half_md4
		reserved_ratio = 0.0
		num_backup_sb = 0
		packed_meta_blocks = 1
		make_hugefiles = 1
		inode_ratio = 4194304
		hugefiles_dir = /storage
		hugefiles_name = huge-file
		hugefiles_digits = 0
		hugefiles_size = 0
		hugefiles_align = 256M
		hugefiles_align_disk = true
		num_hugefiles = 1
		zero_hugefiles = false
	}
	bigdata = {
		errors = remount-ro
		features = has_journal,extent,huge_file,flex_bg,metadata_csum,64bit,dir_nlink,extra_isize,bigalloc,^uninit_bg,sparse_super2
		inode_size = 256
		inode_ratio = 4194304
		cluster_size = 4194304
		reserved_ratio = 0
		lazy_itable_init = 0
		lazy_journal_init = 0
	}