
      Chapter 30. What once was new
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Chapter 30. What once was new


AMANDA Core Team

Original text
AMANDA Core Team

Stefan G. Weichinger

XML-conversion, Updates
AMANDA Core Team
<sgw@amanda.org>
Table of Contents


  What's_new_in_AMANDA_2.3


        Indexing_backups_for_easier_restore

        Samba_Support

        GnuTar_Support

        Multiple_backups_in_parallel_from_one_client_host

        Multiple_tapes_in_one_run

        Bottleneck_determination

        2_Gb_limit_removed

        amadmin_import/export


  What's_new_in_AMANDA_2.2


        Client_side_setup_has_changed

        Version_suffixes_on_executables

        Kerberos

        Multiple_holding_disks

        Remote_self-checks

        mmap_support

        gzip_support

        Mount_point_names_in_disklist

        Initial_tape-changer_support_included

        Generic_tape_changer_wrapper_script

        New_command_amtape

        Changer_support_added_to_command_amlabel

        Tape_changer_support_improved

        A_few_words_about_multi-tape_runs

        Big_planner_changes

        Level-0_dumps_allowed_with_no_tape



Note

Refer to http://www.amanda.org/docs/whatwasnew.html for the current version of
this document.

 What's new in AMANDA 2.3

This document contains notes on new features in AMANDA 2.3 that may not yet be
fully documented elsewhere.

 Indexing backups for easier restore

Read more about this in the file named Indexing_with_AMANDA.

 Samba Support

Read more about this in the file named Backup_PC_hosts_using_Samba.

 GnuTar Support

AMANDA now supports dumps made via GnuTAR. To use this, set your dumptypes set
the program name to "GNUTAR":

  dumptype tar-client {
  ....
  program "GNUTAR"
  }
  	

Since Gnu TAR does not maintain a dumpdates file itself, nor give an estimate
of backup size, those need to be done within AMANDA. AMANDA maintains an /etc/
amandates file to track the backup dates analogously to how dump does it.
NOTE: if your /etc directory is not writable by your dumpuser, you'll have to
create the empty file initially by hand, and make it writable by your dumpuser
ala /etc/dumpdates.
NOTE: Since tar traverses the directory hierarchy and reads files as a regular
user would, it must run as root. The two new AMANDA programs calcsize and
runtar therefore must be installed setuid root. I've made them as simple as
possible to to avoid potential security holes.

 Multiple backups in parallel from one client host

A new "maxdumps" parameter for the conf file gives the default value for the
amount of parallelism per client:

  maxdumps 2 # default max num. dumps to do in parallel per client
  	

If this default parameter is not specified, the default for the default :-0 is
1. Then, you can override the parameter per client through the dumptype, eg:

  dumptype fast-client {
  ....
  maxdumps 4
  }
  	

If the "maxdumps" parameter isn't given in the dumptypes, the default is used.
The idea is that maxdumps is set roughly proportional to the speed of the
client host. You probably wont get much benefit from setting it very high, but
all but the slowest hosts should be able to handle a maxdumps of at least 2.
AMANDA doesn't really have any per-host parameters, just per-disk, so the per-
client-host maxdumps is taken from the last disk listed for that host.
Just to make things more complicated, I've added the ability to specify a
"spindle number" for each filesystem in the disklist file. For example:

          wiggum /        fast-comp-user  0
          wiggum /usr     fast-comp-user  0
          wiggum /larry   fast-comp-user  1
          wiggum /curly   fast-comp-user  1
          wiggum /moe     fast-comp-user  1
          wiggum /itchy   fast-comp-user  2
          wiggum /scratchy fast-comp-user 3
  	

The spindle number represents the disk number, eg every filesystem on sd0 can
get a spindle number of 0, everything on sd1 gets spindle 1, etc (but there's
no enforced requirement that there be a match with the underlying hardware
situation). Now, even with a high maxdumps, AMANDA will refrain from scheduling
two disks on the same spindle at the same time, which would just slow them both
down by adding a lot of seeks.
The default spindle if you don't specify one is -1, which is defined to be a
spindle that doesn't interfere with itself. That is if you don't specify any
spindle numbers, any and all filesystems on the host can be scheduled
concurrently up to the maxdumps.
Just to be clear, there's no relation between spindle numbers and maxdumps:
number the spindles by the disks that you have, even if that's more than
maxdumps.
Also, I'm not sure that putting spindle numbers everywhere is of much value:
their purpose is to prevent multiple big dumps from being run at the same time
on two partitions on the same disk, on the theory that the extra seeking
between the partitions would cause the dumps to run slower than they would if
they ran sequentially. But, given the client-side compression and network
output that must occur between blocks read from the disk, there may be enough
slack time at the disk to support the seeks and have a little parallelism left
over to do some good.

 Multiple tapes in one run

I've rewritten the taper - it now supports one run spanning multiple tapes if
you have a tape-changer. The necessary changes in support of this have also
been made to driver and reporter - planner already had support. There are a
couple other places that should probably be updated, like amcheck. Dumps are
not split across tapes - when taper runs into the end of a tape, it loads the
next tape and tells driver to try sending the dump again.
If you are feeling brave, set "runtapes" to something other than 1.
The new taper also keeps the tape open the entire time it is writing the files
out - no more having amchecks or other accesses/rewinds in the middle of the
run screw you royally if they hit when the tape is closed for writing a
filemark.

 Bottleneck determination

I've made some experimental changes to driver to determine what the bottleneck
is at any time. Since AMANDA tries to do many things at once, it's hard to
pinpoint a single bottleneck, but I "think" I've got it down well enough to say
something useful. For now it just outputs the current bottleneck as part of its
"driver: state" line in the debug output, but once I'm comfortable with its
conclusions, I'll output it to the log file and have the reporter generate a
nice table. The current choices are:

* not-idle - if there were dumps to do, they got done
* no-dumpers - there were dumps to do but no dumpers free
* no-hold - there were dumps to do and dumpers free but the dumps
* couldn't go to the holding disks (no-hold conf flag)
* no-diskspace - no diskspace on holding disks
* no-bandwidth - ran out of bandwidth
* client-constrained - couldn't start any dumps because the clients were busy


 2 Gb limit removed

I've fixed the 2-gig limits by representing sizes in Kbytes instead of bytes
everywhere. This gives us a new 2 TB dump-file size limit (on 32bit machines),
which should last us a couple more years. This seemed preferable to me than
going to long-long or some other non-portable type for the size.

 amadmin import/export

amadmin now has "import" and "export" commands, to convert the curinfo database
to/from text format, for: moving an AMANDA server to a different arch,
compressing the database after deleting lots of hosts, or editing one or all
entries in batch form or via a script.

 What's new in AMANDA 2.2


Note

Here's the old 2.2.x stuff from this file. I'm pretty sure most of this is in
the mainline documentation already.
This document contains notes on new features in AMANDA 2.2 that may not yet be
fully documented elsewhere.

 Client side setup has changed

The new /etc/services lines are:

  amanda       10080/udp		# bsd security AMANDA daemon
  kamanda      10081/udp		# krb4 security AMANDA daemon

The new /etc/inetd.conf lines are:

  amanda  dgram udp wait /usr/local/libexec/amanda/amandad amandad
  kamanda dgram udp wait /usr/local/libexec/amanda/amandad amandad -krb4

(you don't need the vanilla AMANDA lines if you are using kerberos for
everything, and vice-versa)

 Version suffixes on executables

The new USE_VERSION_SUFFIXES define in options.h controls whether to install
the AMANDA executables with the version number attached to the name, eg
"amdump-2.2.1". I recommend that you leave this defined, since this allows
multiple versions to co-exist - particularly important while AMANDA 2.2 is
under development. You can always symlink the names without the version suffix
to the version you want to be your "production" version.

 Kerberos

Read the comments in Using_Kerberos_with_AMANDA for how to configure the
kerberos version. With KRB4_SECURITY defined, there are two new dumptype
options:

*
    krb4-auth	# use krb4 auth for this host
    		# (you can mingle krb hosts & bsd .rhosts in one conf)
    	

*
    kencrypt	# encrypt this filesystem over the net using the krb4
    		# session key.  About 2x slower.  Good for those root
    		# partitions containing your keyfiles.  Don't want to
    		# give away the keys to an ethernet sniffer!
    	



 Multiple holding disks

You can have more than one holding disk for those really big installations.
Just add extra diskdir and disksize lines to your amanda.conf:

Note

sgw: This is OLD syntax now ...

  	diskdir "/AMANDA2/AMANDA/work"  # where the holding disk is
  	disksize 880 MB                 # how much space can we use on it

  	diskdir "/dumps/AMANDA/work"    # a second holding disk!
  	disksize 1500 MB
  	

AMANDA will load-balance between the two disks as long as there is space.
AMANDA now also actually stats files to get a more accurate view of available
and used disk space while running.

 Remote self-checks

amcheck will now cause self-checks to run on the client hosts, quickly
detecting which hosts are up and communicating, which have permissions
problems, etc. This is amazingly fast for what it does: here it checks more
than 130 hosts in less than a minute. My favorite gee-whiz new feature! The new
-s and -c options control whether server-only or client-only checks are done.

 mmap support

System V shared memory primitives are no longer required on the server side, if
your system has a version of mmap() that will allocate anonymous memory. BSD
4.4 systems (and OSF/1) have an explicitly anonymous mmap() type, but others
(like SunOS) support the trick of mmap'ing /dev/zero for the same effect.
AMANDA should work with both varieties.
Defined HAVE_SYSVSHM or HAVE_MMAP (or both) in config.h. If you have both,
SYSVSHM is selected (simply because this code in AMANDA is more mature, not
because the sysv stuff is better).

 gzip support

This was most requested feature #1; I've finally slipped it in. Define
HAVE_GZIP in options.h. See options.h-vanilla for details. There are two new
amanda.conf dumptype options "compress-fast" and "compress-best". The default
is "compress-fast". With gzip, compress-fast seems to always do better than the
old lzw compress (in particular it will never expand the file), and runs faster
too. Gzip's compress-best does very good compression, but is about twice as
slow as the old lzw compress, so you don't want to use it for filesystems that
take a long time to full-dump anyway.

 Mount point names in disklist

Most requested feature #2: You can specify mount names in the disklist instead
of dev names. The rule is, if the filesystem name starts with a slash, it is a
mount point name, if it doesn't, it is a dev name, and has DEVDIR prepended.
For example:

  	obelix	sd0a		# dev-name: /dev/sd0a
  	obelix	/obelix		# mount name: /obelix, aka /dev/sd0g
  	


 Initial tape-changer support included

A new amanda.conf parameter, tpchanger, controls whether AMANDA communicates
with a tape changer program to load tapes rather than just opening the tapedev
itself. The tpchanger parameter is a string which specifies the name of a
program that follows the API specified in AMANDA_Tape_Changer_Support. Read
that for more information.

 Generic tape changer wrapper script

An initial tape-changer glue script, chg-generic.sh, implements the AMANDA
changer API using an array of tape devices to simulate a tape changer, with the
device names specified via a conf file. This script can be quickly customized
by inserting calls tape-changer-specific programs at appropriate places, making
support for new changers painless. If you know what command to execute to get
your changer to put a particular tape in the drive, you can get AMANDA to
support your changer.
The generic script works as-is for sites that want to cascade between two or
more tape drives hooked directly up to the tape server host. It also should
work as-is with tape-changer drivers that use separate device names to specify
the slot to be loaded, wheres simply opening the slot device causes the tape
from that slot to be loaded.
chg-generic has its own small conf file. See example/chg-generic.conf for a
documented sample.

 New command amtape

amtape is the user front-end to the AMANDA tape changer support facilities. The
operators can use amtape to load tapes for restores, position the changer, see
what AMANDA tapes are loaded in the tape rack, and see which tape would be
picked by taper for the next amdump run.
No man page yet, but running amtape with no arguments gives a detailed usage
statement. See AMANDA_Tape_Changer_Support for more info.

Note

sgw: The manpage exists now.

 Changer support added to command amlabel

The amlabel command now takes an optional slot argument for labeling particular
tapes in the tape rack. See AMANDA_Tape_Changer_Support for more info.

 Tape changer support improved

The specs in AMANDA_Tape_Changer_Support have been updated, and the code
changed to match. The major difference is that AMANDA no longer assumes slots
in the tape rack are numbered from 0 to N-1. They can be numbered or labeled in
any manner that suits your tape-changer, AMANDA doesn't care what the actual
slot names are. Also added "first" and "last" slot specifiers, and an -eject
command.
The chg-generic.sh tape changer script now has new "firstslot", "lastslot", and
"needeject" parameters for the chg-generic.conf file. It now keeps track of
whether the current slot is loaded into the drive, so that it can issue an
explicit eject command for those tape changers that need one. See example/chg-
generic.conf for more info.

 A few words about multi-tape runs

I'm still holding back on support for multiple tapes in one run. I'm not yet
completely happy with how AMANDA should handle splitting dumps across tapes (eg
when end-of-tape is encountered in the middle of a long dump). For example,
this creates issues for amrestore, which currently doesn't know about
configurations or tape changers --- on purpose, so that you can do restores on
any machine with a tape drive, not just the server, and so that you can recover
with no online databases present.
However, because the current snapshot DOES support tape changers, and multiple
runs in one day, some of the benefit of multi-tape runs can be had by simply
running AMANDA several times in a row. Eg, to fill three tapes per night, you
can put

  amdump <conf>; amdump <conf>; amdump <conf>

in you crontab. On the down side, this will generate three reports instead of
one, will do more incremental dumps than necessary, and will run slower. Not
very satisfying, but if you need to fill more than one tape per day NOW, it
should work.

 Big planner changes

The support for writing to multiple tapes in one run is almost finished now.
See Multitape_support_in_AMANDA_2.2 for an outline of the design. The planner
support for this is included in this snapshot, but the taper part is not.
There is a new amanda.conf variable "runtapes" which specifies the number of
tapes to use on each amdump run. For now this should stay at 1, the default.
Also, the old "mincycle" and "maxcycle" amanda.conf variables are deprecated,
but still work for now. "maxcycle" was never used, and "mincycle" is now called
"dumpcycle".
There are two visible differences in the new planner: First, planner now thinks
in real-time, rather than by the number of tapes as before. That is, a
filesystem is due for a full backup once every <dumpcycle> days, regardless of
how many times AMANDA is run in that interval. As a consequence, you need to
make sure the dumpcycle variable marks real time instead of the number of days.
For example, previously "mincycle 10" worked for a two week cycle if you ran
amdump only on weekdays (for 10 runs in a cycle). Now a two week cycle must be
specified as "dumpcycle 14" or "dumpcycle 2 weeks". The "2 weeks" specifier
works with both the old and new versions of planner, because previously "weeks"
multiplied by 5, and now it multiplies by 7.
Second, planner now warns about impending overwrites of full backups. If a
filesystem's last full backup is on a tape that is due to be overwritten in the
next 5 runs, planner will give you a heads-up about it, so that you can restore
the filesystem somewhere, or switch that tape out of rotation (substitute a new
tape with the same label). This situation often occurs after a hardware failure
brings a machine or disk down for some days.

 Level-0 dumps allowed with no tape

If there is no tape present (or the tape drive fails during dumping), AMANDA
switches to degraded mode. In degraded mode, level-0 dumps are not allowed.
This can be a pain for unattended sites over the weekend (especially when there
is a large holding disk that can hold any necessary dumps). AMANDA now supports
a new configuration file directive, "reserve". This tells AMANDA to reserve
that percentage of total holding disk space for degraded mode dumps. Example:
your total holding disk space adds up to 8.4GB. If you specify a reserve of 50,
4.2GB (50%) of the holding disk space will be allowed to be used for regular
dumps, but if that limit is hit, AMANDA will switch to degraded dumps. For
backward compatibility, if no 'reserve' keyword is present, 100 will be assumed
(e.g. never do full dumps if degraded mode is in effect).

Note

This percentage applies from run to run, so, as in the previous example, when
AMANDA runs the next day, if there is 3.8GB left on the holding disk, 1.9GB
will be reserved for degraded mode dumps (e.g. the percentage keeps sliding).
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