Re: [flexbackup-help] Version 1.01 and mt setblk in Linux

[Edwin H. <ed...@co...>]

[ Luis Cortes wrote: ]
> Okay, let me clarify my own response.  I believe that for programs like tar
> or cpio, the default block size is 512.  When you specify 64 blocks,

Nope.

tar and many others default to 10k.  cpio does default to 512 bytes.  We
don't use defaults for anything anyway, so it doesn't matter.

> flexbackup thinks it's 1024 * 64.  If you specify 64 blocks for cpio it
> means 512 * 64.  It seems to me that there is a logic problem somewhere.  Am
> I right about this?

Nope.

The config file says "Block size (k)" for $blksize, and that's what it
means.  It's converted for whichever archiver as needed.

Flexbackup sets the flags are all set so units are consistent.  Check the
manpages and code.


tar:
  -b, --block-size N
         block size of Nx512 bytes (default N=20)

cpio: (flexbackup uses the -C flag!)
  -C IO-SIZE, --io-size=IO-SIZE
        Set the I/O block size to IO-SIZE bytes.

dump:
  -b blocksize
             The number of kilobytes per dump record.  Since the IO system
             slices all requests into chunks of MAXBSIZE (typically 64kB), it
             is not possible to use a larger blocksize without having problems
             later with restore(8).  Therefore dump will constrain writes to
             MAXBSIZE.  The default blocksize is 10.

afio:
  -b size      Read  or write size-character archive blocks.  Suffices of
               b,  k,  m  and  g  denote  multiples  of  512,  kilobytes,
               megabytes  and  gigabytes, respectively.  Defaults to 5120
               for compatibility with cpio(1).  In  some  cases,  notably
               when  using  ftape with some tape drives, -b 10k is needed
               for compatibility.  Note that -b 10k is the default  block
               size used by tar(1), so it is usually a good choice if the
               tape setup is known to work with tar(1).

etc..

-- 
 Edwin Huffstutler     Linux - because reboots are for hardware changes
 ed...@co...   GnuPG Key ID: AE782DC9