Networker

Re: [Networker] DDS

2006-06-12 05:43:47
Subject: Re: [Networker] DDS
From: Pascal Rijs <pascal.rijs AT UNILEVER DOT COM>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Mon, 12 Jun 2006 05:38:54 -0400
I agree; SAN technology makes a thing like DDS posible and greatly 
improves ROI and backup performance.

We too experienced problems with the fragile SAN DDS setup. The most 
important thing to do is apply zoning per connection. This prevents new or 
dropped SAN connections to change sequence numbers for other conections in 
the same zone; which would lead to other scsi ID/luns and causing the 
backup server to become out of sync with the SAN Storage Nodes (DDS 
clients). Also it's very important to always start your SAN in exacly the 
same order when using multiple switches. I wish FC networks could be as 
nicely configured as IP networks (FIXED LINKS/IPs); especially with 
dynamicly detecting clients like Windows 2000 and 2003. Your big friend is 
the command 'inquire'.

The big plus of DDS: backup server offload and one saveset of one client 
streaming to tape at a time. The latter heavily improves cloning and/or 
restore times. Also an available drive will not remain unused for long.






On Fri, 9 Jun 2006 17:59:16 +0530, Shyam Hegde <hegde.shyam AT GMAIL DOT COM> 
wrote:

>Hello,
>
>My experience with DDS is fine but only I get in to trouble when some
>parameters of the NetWorker backup zone environment are changed (such
>as changes in SAN zoning, hardware upgrade, replacement etc.)
>I think one has to be very careful in DDS environment when there is a
>hardware changes in NetWorker Server and Storage Nodes and also NDMP 
clients
>if there are any (Like adding one more card on the boards, changing HBAs)
>and also proper understanding of the visibility of the drives and robotic
>accordingly to the hosts in your environment.  All to do with drive device
>path and element addres sequence. It helps documenting these details on a
>new install and a successful testings.
>
>Also I had a problem of drives getting reset when one of the servers did
>restart (which is a storage node and has visibility to the drives) which
>caused issues with the running backup of other storage nodes. (The tape 
was
>done a re-wind during the instance i guess )
>
>But I do not see why one should not go for DDS option which is the most
>significant factor in ROI of a SAN investment when it comes to the 
subject -
>backup!
>
>Regards
>Shyam
>
>
>On 6/9/06, N.J.Tustain <N.J.Tustain AT open.ac DOT uk> wrote:
>>
>> Hi,
>>
>>
>> What are peoples experience of using DDS with dedicated storage nodes?
>>
>> We've been using this arrangement for several months, when it's all
>> working the backup rate is excellent, but whole thing seems very
>> problematic. Also, when there is an issue, we never seem to able to get
>> to the bottom of what went wrong.
>>
>> A Networker reseller has recently told us they advise their customers
>> against using DDS. Something along the lines that DDS is effectively
>> removing/attaching a SCSI device from a running server.....which causes
>> problems.  If that's correct that would be a fairly fundamental flaw in
>> the design...?
>>
>>
>>
>> Thanks
>> Nick
>>
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>
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