"Dennis Clarke" <[EMAIL PROTECTED]> wrote:
> The format of the stream is evolving. No backwards compati-
> bility is guaranteed. You may not be able to receive your
> streams on future versions of ZFS.
This is a good point even if your claim on ZFSs "send/receive" format
may be wrong. The POSIX.1-2001 extended tar archive format is a format
that you may safely rely on. It is infinitely expandable and this is important
for future enhancements.
> This leaves us with tar or cpio or Joerg Schillings star. But if you
The archive format supported by the current "Solaris tar" is not sufficient for
doing backups. A lot of important information is missing that is needed in order
to create incremental backups.
cpio is a "dead end" archive format. There are already 4 completely incompatible
cpio archive formats. There are currently two different "revetn" cpio archive
formats:
- The POSIX variant. It supports a max. filesize of 8 GB -2 byte but
limits UID/GID as well as dev/ino to a range from 0 ... 262143
- The Svr4 variant. It allows UID/GID as well as dev/ino to be in the
range 0 ... 4294967295 but it limits file size to 4 GB - 2 byte.
and it is hard to further enhance the limited format.
In addition, Sun "Solaris tar" as well as cpio do not support sparse files.
Star supports all needed features and in addition implements incremental backups
using the same basic algorithm als ufsdump.
> have many man file systems and they are larger than a LTO tape ( or
> whatever media du jour ) then you will need to figure out a way to do
> the backups. Somehow.
With star, you may do incremental backups and multi volume archives
that span more than one tape.
> How shall we begin ?
>
> Maybe with a definition of what a "backup" is and then some way to
> achieve it. As far as I know the only real backup is one that can be
> tossed into a vault and locked away for seven years. Or any arbitrary
> amount of time within in reason. Like a decade or a century. But
> perhaps a backup today will have as much meaning as papertape over
> time.
A real backup can be done using star on a snaphot.
> Can we discuss this with a few objectives ? Like define "backup" and
> then describe mechanisms that may achieve one? Or a really big
> question that I guess I have to ask, do we even care anymore?
If you have questions on backup features and whether they are already
implemented in star or possible/impossible in the future, please ask.
Jörg
--
EMail:[EMAIL PROTECTED] (home) Jörg Schilling D-13353 Berlin
[EMAIL PROTECTED] (uni)
[EMAIL PROTECTED] (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily
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