Hello,
In my opinion, AFTD may be easier to manage and have cost advantage over
VTL's, especially, if Data Domain type of disk's are used for AFTD, since,
there is little if any configuration to manage in AFTD environment ( On
the appliance side), VTL with Data Dedupe had advantage over AFTD until ,
DD was introduced with Data Domain, AFTD will result in higher storage
capacity utilized as there is no space left unused , unlike Tapes which
can be underutilized, if not sized and managed properly.
On the other hand, VTL provides proven and known interface and procedures
in relationship to Tapes do not have to be altered much, they offer usual
benefit of speeding up slower clients and help with Tape shoeshining
issues.
At this time, i am leaning towards AFTD behind Dedupe Appliance, as
replication technology becomes more prevalent, which in my opinion has
higher value in Dedupe appliance, sizing and capacity uplift should
considered to be significant factor in any VTL or AFTD environment.
Some NDMP implementation will also require the use of VTL vs AFTD, in that
case, a mix of VTL and AFTD should be considered.
HTH
Curtis Preston <cpreston AT GLASSHOUSE DOT COM>
Sent by: EMC NetWorker discussion <NETWORKER AT LISTSERV.TEMPLE DOT EDU>
08/19/2008 06:21 PM
Please respond to
EMC NetWorker discussion <NETWORKER AT LISTSERV.TEMPLE DOT EDU>; Please respond
to
Curtis Preston <cpreston AT GLASSHOUSE DOT COM>
To
NETWORKER AT LISTSERV.TEMPLE DOT EDU
cc
Subject
Re: Query in Staging from adv_file
So an AFTD can service multiple concurrent restore requests, but can't
service multiple destaging/cloning requests?
I still say the VTL is easier. The difference is that a backup associated
with a given AFTD can only be cloned/destaged by the AFTD that stored it,
where a VTL allows any-to-any relationship of virtual drives.
If I have 20 virtual tapes and 20 virtual drives, I can clone/destage them
all at once, regardless of how many drives were used to create them. If
an AFTD can only clone/destage one backup at once, and I want to be able
to destage 20 AFTD backups, I have to make sure that each of them is on a
separate AFTD. I don't think that's even possible, let alone practical.
Am I missing something?
Curtis Preston | VP Data Protection
GlassHouse Technologies, Inc.
T: +1 760 710 2004 | C: +1 760 419 5838 | F: F: +1 760 710 2009
cpreston AT glasshouse DOT com | www.glasshouse.com
Infrastructure :: Optimized
-----Original Message-----
From: EMC NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On
Behalf Of Preston de Guise
Sent: Tuesday, August 19, 2008 3:48 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: Re: [Networker] Query in Staging from adv_file
On 20/08/2008, at 8:35 AM, Stan Horwitz wrote:
> On Aug 19, 2008, at 6:16 PM, Curtis Preston wrote:
>
>> Well, that significantly decreases the value of AFTDs over VTLs in
>> NetWorker, now doesn't it?
>
> I have no experience with a VTL, but my impression is that you get
> the same functionality as physical tape drives, but on disk. If so,
> doesn't that limit the amount of streams that can be read from a
> virtual tape to just one session at a time, or does it parlay the
> fact that multiple local tapes can be serviced concurrently in a VTL?
In theory it doesn't make AFTDs any worse than VTLs, since neither
scenario supports more than one staging operating reading from the
same volume at the same time.
However, in practice VTLs will normally be configured such that there
are a high number of virtual tape drives and a high number of smaller
sized virtual volumes, making it possible to execute more concurrent
reads than either a conventional PTL or a AFTD.
I wouldn't however say that it significantly decreases the value of
AFTDs over VTLs in NetWorker - it entirely depends on what your needs
are. In an environment that requires high levels of recovery
activities, AFTDs may still win out over VTLs - e.g., a previous
customer of mine had a configuration that required 400-600+ recoveries
per working day (i.e., an 8 hour period each day); in this sort of
scenario AFTDs with their ability to allow as many concurrent recovery
sessions as requested are of course King.
Cheers,
Preston.
--
Preston de Guise
"Enterprise Systems Backup and Recovery: A Corporate Insurance
Policy", due out September 17 2008:
http://www.crcpress.com/shopping_cart/products/product_detail.asp?sku=AU6396&isbn=9781420076394&parent_id=&pc=
http://www.enterprisesystemsbackup.com
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