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Full Discussion: Optimal block size in dd
Operating Systems HP-UX Optimal block size in dd Post 302427397 by jim mcnamara on Saturday 5th of June 2010 06:11:56 AM
Old 06-05-2010
Have you tried cpio?

The only rule of thumb I know is for disks - use a dd blocksize that == 2 or 4 times the size of the physical blocks on the disks, whether reading or writing. This is the fundamental blocksize, not what df reports. For example you can use fdisk on linux to see blocksize. Don't remember for HPUX.

Since tape is far slower than disk i/o, I dunno if this helps.

The f_frsize value returned in struct stavfs:
u_long f_frsize; /* fundamental filesystem block
(size if supported) */
 

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DUMPE2FS(8)						      System Manager's Manual						       DUMPE2FS(8)

NAME
dumpe2fs - dump ext2/ext3/ext4 filesystem information SYNOPSIS
dumpe2fs [ -bfghixV ] [ -o superblock=superblock ] [ -o blocksize=blocksize ] device DESCRIPTION
dumpe2fs prints the super block and blocks group information for the filesystem present on device. Note: When used with a mounted filesystem, the printed information may be old or inconsistent. OPTIONS
-b print the blocks which are reserved as bad in the filesystem. -o superblock=superblock use the block superblock when examining the filesystem. This option is not usually needed except by a filesystem wizard who is examining the remains of a very badly corrupted filesystem. -o blocksize=blocksize use blocks of blocksize bytes when examining the filesystem. This option is not usually needed except by a filesystem wizard who is examining the remains of a very badly corrupted filesystem. -f force dumpe2fs to display a filesystem even though it may have some filesystem feature flags which dumpe2fs may not understand (and which can cause some of dumpe2fs's display to be suspect). -g display the group descriptor information in a machine readable colon-separated value format. The fields displayed are the group number; the number of the first block in the group; the superblock location (or -1 if not present); the range of blocks used by the group descriptors (or -1 if not present); the block bitmap location; the inode bitmap location; and the range of blocks used by the inode table. -h only display the superblock information and not any of the block group descriptor detail information. -i display the filesystem data from an image file created by e2image, using device as the pathname to the image file. -x print the detailed group information block numbers in hexadecimal format -V print the version number of dumpe2fs and exit. BUGS
You need to know the physical filesystem structure to understand the output. AUTHOR
dumpe2fs was written by Remy Card <Remy.Card@linux.org>. It is currently being maintained by Theodore Ts'o <tytso@alum.mit.edu>. AVAILABILITY
dumpe2fs is part of the e2fsprogs package and is available from http://e2fsprogs.sourceforge.net. SEE ALSO
e2fsck(8), mke2fs(8), tune2fs(8). ext4(5) E2fsprogs version 1.44.1 March 2018 DUMPE2FS(8)
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