[Techtalk] seeking backup solution recommendations

Conor Daly c.daly at met.ie
Tue Feb 2 10:18:49 UTC 2021


Hi Meryll,

I know it's a while ago now but I'm wondering did you get a solution?

I have used unix Dump/Restore as a backup solution for production servers
for many years.  The advantage of dump over tar is that it does things like
start a catalog at the beginning of the dump so you don't have to read the
whole tape to see what's on it.  It's also cross-server retrievable and it
can do tape changes.

I think it covers all your bases...

Comments inline below

Regards,

Conor


On Sat, Nov 28, 2020 at 09:52:11AM -0800 or thereabouts, Meryll Larkin wrote:
> Hi Systers,
> 
>  
> 
> I'm searching online too, but I thought emailing this list might help me as
> some of you probably have experience with different backup solutions.
> 
>  
> 
> The environment that I am backing up has the following features:
> 
> 1.      Only Linux servers in the LAN- no other OS.

Yep, same here.
 
> 2.      Only ONE DIRECTORY really requires backup.  That directory is 140 T
> in size, but currently contains 25 T of data.  That could double over the
> next 4 years, not sooner.

Sounds like lots of tapes.  Does that have a decent sub-directory structure?
Does it have an 'archive' area that does not change as well as an 'active'
area where changes occur?  This can affect how you backup.  You could use a
backup plan like:

  1st of month:  Full backup of 'archive' area.  Might take a day or
                 more to complete depending on drive speed. 

  Friday:        Full backup of 'active' area.  This starts when everybody
                 is gone for the weekend.  Not too long as only 'active' are
                 is backed up.

  Mon - Thu:     Level 1 (incremental) backup of 'active' area.  This is
		 pretty quick as it only backs up changes since last full
                 backup.
 
> 3.      Some of the files in that one directory are 20G in size, and they
> could get larger.

Is it the case that a file will be actively growing and can you schedule
backups for when this is not happening?
 
> 4.      We have a tape drive - which we have been using to make backups
> using "tar".  That has reached its useful limit with those large files.
> The tapes hold about 12T of uncompressed data, each.  We have several tapes.
> We have never gotten the "Autoloader" feature to work on the tape drive, but
> we can move the tapes manually, remotely.  I'm smart about selecting pieces
> to backup that fit on each tape.

dump has a '-F <script>' switch which specifies a script to run when a tape
fills.  Because it's just a path to a script, you control what it does.  In
my case, the 'swaptape.sh' script does the work on the autoloader using the
'mtx' command.  

I developed a fairly simple (I hope!) configuration to manage tapes and
filesystems.  It looks something like this:

###########################################################
Slot    Filesystem(s)
1-3     srv3:/ srv3:/boot srv3:/home srv3:/d8 srv2:/archive
4       / /boot /home /usr /var /db_ckpt
# comment
###########################################################

Slot 1-3 indicates the backup should start on the tape in slot 1 and should
use the tape in slot 2 when tape 1 fills, moving on to slot 3 when tape 2
fills.  
Slot 4 indicates the backup should use only the tape in slot 4 and will fail
if this tape fills.

srv3:/home says backup filesystem /home on remote server 'srv3'

/db_ckpt says backup the database checkpoint filesystem '/db_ckpt' on the
local machine.

Log output from the backup looks like:

Starting MASTER backups
Target: bkpsrv:/dev/nst0
Filesystem      | Level | Slot  | Barcode       | Start date       | Status | Finish date      | Barcode
-----------------------------------------------------------------------------------------------------------
srv3:/          |   1   |   2   | 000059L5      | 2021-02-01 17:06 | Success | 2021-02-01 17:08 | 000059L5
srv3:/boot      |   1   |   2   | 000059L5      | 2021-02-01 17:08 | Success | 2021-02-01 17:08 | 000059L5
srv3:/home      |   1   |   2   | 000059L5      | 2021-02-01 17:08 | Success | 2021-02-01 17:46 | 000059L5
srv3:/d8        |   1   |   2   | 000059L5      | 2021-02-01 17:46 | Success | 2021-02-01 18:45 | 000059L5
srv2:/archive   |   1   |   2   | 000059L5      | 2021-02-01 19:05 | Success | 2021-02-01 19:05 | 000059L5
-----------------------------------------------------------------------------------------------------------
Filesystem      | Level | Slot  | Barcode       | Start date       | Status | Finish date      | Barcode
-----------------------------------------------------------------------------------------------------------
/               |   1   |   3   | 000060L5      | 2021-02-01 19:11 | Success | 2021-02-01 19:11 | 000060L5
/boot           |   1   |   3   | 000060L5      | 2021-02-01 19:11 | Success | 2021-02-01 19:11 | 000060L5
/home           |   1   |   3   | 000060L5      | 2021-02-01 19:11 | Success | 2021-02-01 19:11 | 000060L5
/usr            |   1   |   3   | 000060L5      | 2021-02-01 19:11 | Success | 2021-02-01 19:12 | 000060L5
/var            |   1   |   3   | 000060L5      | 2021-02-01 19:12 | Success | 2021-02-01 19:12 | 000060L5
/db_ckpt        |   1   |   3   | 000060L5      | 2021-02-01 19:12 | Success | 2021-02-01 19:15 | 000060L5
-----------------------------------------------------------------------------------------------------------

and the detailed dump output goes to a second logfile to be studied in the
case of error.

Our tape library has a barcode reader so these are logged also.  The tape
change shows up as something like:

srv2:/archive   |   0   |   1   | 000050L5      | 2021-01-27 21:29 | Success | 2021-01-28 07:49 | 000059L5

where the second barcode differs from the first.

It all depends on basic unix tape tools which you will have installed to
manage your tape library:

  mt:         Interact with the tape in the drive
  mtx:        Interact with the tape library
  dump:       Backup ext2/3/4 filesystems
  restore:    Restore ext2/3/4 filesystems
  xfsdump:    Backup xfs filesystems
  xfsrestore: Restore xfs filesystems

I did have an issue with xfsdump on large filesystems where the backup would
fail to resume on tape change which seemed to be down to a hardware
mismatch.  I think it was eventually resolved.
 
> 5.      We have an internal DNS server for the LAN only, I mention this
> because I remember a decade ago some backup solutions needed to use server
> names and have reverse lookup.  We can do that.

I don't think dump requires this, it can likely do ip addresses.
 
> 6.      We don't currently have email going in or out of the LAN.  The email
> sits in /var/spool/mail.  So what that means is that if there is a GUI
> dashboard, the GUI will need to display errors.  It would be helpful to be
> able to see errors some way OTHER than email notifications.  Okay if I need
> to use command line to pull them.

My solution would output to log files.  Chunks of these would get emailed
but I had an active log review schedule every morning.
 
> 7.      This is ALSO our backup and recovery plan so it is IMPORTANT that
> Restores can be done from storage media EVEN IF the original server that
> created the backup is destroyed.  In other words, I need to be able to make
> a new server, install the backup software, and restore to new hardware.  

Yep, dump/restore does this.  Only caveat is matching versions of
dump/restore.  I cannot remember but I suspect a later restore can read
older dumps.
 
> I'm mentioning this because I think SOME encryption algorithms prevent the
> ability to restore from non-original backup software install.
> 
>         I manually retrieve tapes with backups on them so they can be stored
> off-site.
> 
> 8.      Nice to have:  Speed at backing up - because folks using the
> resources don't like to have their processes slowed nor access denied for
> very long.

See my 'archive' vs 'active' suggestion above.  
 
> 9.      Nice to have: Granular Restores

'restore -i' gives you a (very traditional unix) interactive session with a
tape where you can select individual files for restore. 
 
>  
> 
> Suggestions?  Ideas?
> 
> I'd like to hear about BOTH solutions that FIT my criteria AND if you know
> solutions that DON'T (so I don't waste my time in my online research).
> 
>  
> 
> TIA,
> 
> Meryll Larkin
> 
>  
> 
>  
> 
>  
> 
>  
> 
>  
> 
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-- 
Conor Daly (Meteorologist),                   
Met Eireann, Glasnevin Hill,  
Dublin 9, Ireland             
Ph +3531 8064261

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