Veritas-bu

[Veritas-bu] Volume Pools [recommendations please]

2006-04-27 05:46:39
Subject: [Veritas-bu] Volume Pools [recommendations please]
From: dave.markham AT fjserv DOT net (Dave Markham)
Date: Thu, 27 Apr 2006 10:46:39 +0100
My last email on this to try and clear my name a little yet still give
advise to the original poster.

I wrote something in a few words which then had people assuming what i
was meaning. This is my fault for writing it like that and i should have
expanded the point more, although it was only a question to people.
Original quote :

"I am surprised by the number of people using a single volume pool for
data backups. What about mixed retentions on media?"

People then took my understanding to mean either i thought you cannot
have 1 volume pool and have different retentions or having one volume
pool would mean you have backup images of different retentions on the
same tape. Neither of these is what i was trying to say or is my
understanding of netbackup. I simply was saying to the original poster,
who was asking for advise on how to setup a system with what seemed to
me limited netbackup knowledge, was having one volume pool in my opinion
would be difficult to manage if you have the requirement for different
retentions for certain backup images.

The reason for this is either you need to mix retentions on media or you
will have tapes with the same volume pool and different retentions in
your jukebox and not know easily from a glance what tapes are what. Now
i know people from reading this have a use for both of these features
which i guess is why they are there in netbackup, but to the original
poster and to keep things simple for administration and netbackup i
think going down these 2 routes is not wise for a new starter. Some
people have agreed and some people have got their own methods thats all
great but think of the original poster.

I went on to describe my basic setup i put on small to medium solutions
as advise for the poster so they had very few pools which would relate
to retention and it didn't mater on the policy. It also means you can
quickly glance down the media in your jukebox and know what tapes are
what, retention wise, or be it for logs or offsite. I know this is not
for everyone and people have other ways of doing things but it is a
simple solution letting netbackup handle the aspects of media allocation
based on schedules and gives you  good scope for restore and in my case
automated scripts to alert people when to take tapes out and put them in
based on retention. All backup solutions, again in my opinion, should be
designed around the restore requirements.

The original poster reading the thread if hes not fed up by now :) will
beable to fully understand the mixed retentions on media and the aspects
of using one volume pool, and having different schedules with different
retention periods, thanks to everyone who responded. This is only a good
thing.

So to summarize....i understand how netbackup works with retentions and
volume pools and i wasnt saying any individual set up is bad i was
simply saying i was surprised by the number of people using one tape
pool for all data backups and questioned the retention aspects of doing
this both administratively and tape usagely ( i had to put one unknown
word in this reply hehe).

Now can someone answer me what happens if you have a 2 clients in a
policy which has 2 streams as follows :-

NEW_STREAM
/data
/u01
/u02
NEW_STREAM
/devices/something/mp@121,raw
/devices/something/mp@122,raw
/devices/something/mp@123,raw
/devices/something/mp@124,raw

both clients have the directories /data etc (the file system stuff) and
only one client has the raw partitions vvisible. They are both in the
same policy as i want them to write to the same tapes and have the same
retention. I have an exclude_list.<policy> on the client without the raw
partitions containing the raw partitions yet i get a backup exit status
of 71 for this client which is none of files in file list exist.

I know this is because the new_stream will create a new job for that
client but why is the exclude list not being used or is it and its just
no other files are in the list so it exits with 71?

Cheers





bob944 wrote:
>> I think that my words have been taken out of context. I know you cant
>> and shouldn't mix retentions on media which is why i find it hard that
>> people use 1 media pool for all backups. From that i would assume they
>> have the same retention for all backups. This in my opinion which is
>> only my opinion is a bad idea.
>>
>> To give advise to the original thread i was saying that one 
>> volume pool
>> for all backups is perhaps not the right way to do things and i was
>> surprised by the number of people who seemed to adopt it.  I 
>> asked about
>> mixed retentions as people with 1 volume pool cannot ( safely ) then
>> have a full backup with a different retention than say a 
>> cumulative backup.
>>     
>
> Dave, perhaps I'm dense, but I read the above the same as I read your
> original statement:  it seems you are saying that a 1-month-retention
> full can wind up on the same tape as a 1-week-retention cumulative.
> There's no "safely" about it--that _does_ _not_ _happen_ unless you
> force it with use_multiple_retentions_per_media.  Has nothing at all to
> do with volume pools.
>
> Please, what am I misunderstanding about what you are saying?
>
>   
>>> What about them?  NetBackup *never* puts different 
>>>       
>> retentions on a tape
>>     
>>> unless you force it to with the 
>>>       
>> MULTIPLE_RETENTIONS_PER_MEDIA directive
>>     
>>> (and there are very few situations where that's a good idea).
>>>       
>
> And someone asked when that would ever be a good idea.  Two that I've
> found are
>
> o  small robots.  Maybe it's worth having some full, out-of-the-robot
> tapes with mixed retentions sitting around until the longest/newest
> image on it expires versus having, say, eight partial tapes clogging up
> slots in the robot (say, MediaA and MediaB, each backing up clients with
> 1-week and 1-month retentions in two pools.  Throw in
> mux/non-multiplexed, a few more pools, a few special retentions, another
> media server, and ... well, a 30-tape robot just won't cut it for that
> customer.  If you allow multiple retentions, you free up precious slots.
>
> o  moving day.  A couple of clients are moving to another NetBackup
> domain, or maybe you're sending backups to a DR site.  If you make, or
> dup, their dailies, weeklies and last monthly (w/different retentions),
> it's three tapes--or one if you put them all on one tape.
>
> In short, "multiple retentions per media" doesn't hurt a darned thing,
> ever.  It just means that a tape of 1-week-retention dailies that has a
> 1-month-retention weekly on it at the end won't become available for a
> month, rather than a week.  And _that_ is intrinsically no different
> than the "waste" of older images at the beginning of a single-retention
> tape being held hostage to the expiration time of the last image.
>
>
>
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