Any disadvantages of using secondary IPs?

I can't seem to figure out what is the practical difference and what are the consequences of using multiple secondary IP vs creating multiple logical interfaces?
I was wondering if this would bother my router's VoIP functions in anyway?

IMHO, secondary addressing has one primary reason for existance: Orderly transition from one address block to another...then clients on both the old and the new addresses are concurrently operational. Once all the clients are migrated, the origianl address goes away and the new address is made primary.
Beyond that, any other use resluts in sub-optimal operation and performance.
All L2 broadcasts, from either/any secondary subnet, will be seen by all clients (L2 broadcast is all ones ... no distinction from the L3 address).
It doesn't give you any more capability for client count, it doesn't give you any additional capability for anything ... as mentioned, it can screw up your routing protocols and many consider it a security risk.
Using sub-interfaces is a fairly common way to address multiple PVCs on a frame-relay WAN, it's used with 802.1q encaps to speak with a trunk port on a switch (for VLAN routing / inter-VLAN routing).
There are still some adjustments to be made on how you implement your routing protocols.
Sub-interfaces have a couple useful specific roles, secondary addressing used for anything but address migration is a ticking time-bomb (IMHO).
FWIW
Scott

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Java reflection - any disadvantages

1. Are there any disadvantages in using java reflection api (too much)?
2. How do obfuscators deal with reflection based applications?
Thanks
Santosh

Sorry, i wanted to know how the code
Object obj = new MyClass();
is different from
Class clazz = Class.forName("MyClass");
Object obj = clazz.newInstance();
at the byte-code level.
That is, in both the cases the classloader has to
search for MyClass and invoke the constructor. Hope I
am clear :)I don't think there is any difference as far as performance is concerned between the above mentioned methods for instantiating the object of MyClass.
But here is what is generally said about using reflection(u can find it on google):
===============================================================
Don?t overuse the Reflection API. Programs that use it are more difficult to understand and maintain. In addition, accessing fields and calling methods through the Reflection API is slower than using them in the ?normal? way, so use reflection only when it is really necessary.
===============================================================
We too had concerns about reflection's performance, but as long as you cache the lookups, reflection is very fast. What is slow is doing things like looking up a method on a class or looking up an instance member. We do all these lookups once and then cache the results.
===============================================================
Why is it slow as stated above? - Maybe because flexibility always comes at a price !!! Maybe the internal implementation of the call sequence by the JVMs is such that it cannot be implemented any faster...

FCP 6-Working with DV, any disadvantages to H.264 export?

I am working in DV, I want to reduce final files size by exporting using Quicktime Conversion> H.264, I want to know if there are any disadvantages to using this codec for the final exported file?
Thank you,
Sebastian

IT is perfect as your final export type. Nothing wrong with it.
Shane

Any disadvantages using an ordinary PC keyboard?

Are there any disadvnatges of using a standard Windows keyboard?
Are any keys missing for example?
Or do I HAVE to buy an expensive Apple keyboard?
Thanks
Omar

omar.m wrote:
Are there any disadvnatges of using a standard Windows keyboard?
I haven't found too many in normal day to day operations.
Are any keys missing for example?
It's the Apple keyboard that has keys missing.
Do I HAVE to buy an expensive Apple keyboard?
No, you can use a PC keyboard. A wired one should also do the at boot key commands as well.
I've been using cheap disposable PC keyboards for years on my MacBook Pro's for the fact that wearing out the built in one decreases it lifespan and resale options.

Disadvantages of using "0" zero as first value in a generated sequence

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Thanks

Benefit: You get use one "more" number from the list of values that can possibly be generated by the sequence. If you are start from '1', you have missed out on '0' :-)
Disadvantages: If any of the queries have predicate like "sequence_generated_column_value > 0" and that your sequence starts from zero, the record with sequence_generated_column_value=0 will not appear in result set for that query (assuming it satisfies other conditions).
May be there are many mores benefits/disadvantages to add to this list :-)

How to use secondary method in workflow?

Hi friends,
can anyone plz let me know how to use secondary methods in workflow? it would be helpful if u explain with an example..
thanks and regards,
Arun.S

Hi Arun Kumar,
The Sec Method can be used in the user decision step. The secondary methods are executed along with the user decision step. You have 3 options. Either execute a secondary method before executing the user decision step or after execution of user decision step or while executing the user decision.
For this define the methods either in Methods before execution of workitem execution to execute it before user decision step or Methods after execution of workitem so as to execute it after the execution of user decision.
In order to execute a method along with user decision step execution use secondary methods (amodal call.)
Let me know if you have any queries.
Regards,
Raj

What are disadvantages by using field catalogmerge in ALV

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Hi Diva,
I have gone thru the advantages... and don't see and disadvantage in building it thru functions....
The only advantage, that you can maintain dynamically during runtime, the structure of your ALV grid.
Mostly you are using static structures for ALV, so it is easier to create a static structure in SE11 and give this structure to your ALV_GRID_DISPLAY as a parameter.
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Jayant

Disadvantages of Using Externalizable

I know the advantages of using Externalizable.
But Iam trying to figure out if it is useful especially in my case.
I have an object which has other objects within and that object has some more objects, kind of like many-to-one relationsip.
I have been constantly getting java.io.EOFException, when de-serializing. I figured that the reason for that is that Iam putting some null values in my writeExternal method and when de-serializing readExternal spits out java.io.EOFException, coz it reaches end of stream.
That makes me to believe I have to be very careful what I put in output stream before I serialize. This is what I want to know.
Is it advisable to use Externalizable in this kind of situation?
I think Externalizable is a good choice for a class which does not contain many other objects, or whose behaviour is predictable. Agree?
Are there any dis-advantages of Externalizable?
(I could not find one post anywhere on the web about any disadvantages for Externalizable.....:-\ , cant believe if this is so good)
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gujja

if you change the order variables are declared in
your class, the default serialization will change the
order it expects to see the data during
serialization.Untrue.
And also change the order it writes
variables out during serialization.True but irrelevant. Fields are written out as name-value pairs so the ordering is immaterial.
If you implement your own methods, you can change
order of declaration and it will not break your
serialization. This only works if when you implement
your own, you do not call defaultWriteObject and
defaultReadObject.Also untrue. The ways in which you can change your class compatibly are completely defined in the Serialization specification: http://java.sun.com/j2se/1.5.0/docs/guide/serialization/spec/version.html#6678. They include not only changing the order of fields but also adding them.

What is the disadvantages of using Serialization?

HAi all,
I want to store objects in a file. I am preferred to use serialization. But I want to know what are the disadvantages of using Serialization over other methods (direct file, Keyed File)?
Can we store as many records using serialization? Is there any limit? Is there any security related issues?
Pls help me.
regards,
namanc

I don't think there is disadvantage using serialization compare to direct i/o access to file or any storage, except that you need to design your code such as it is serializable (hence, you may want to use transient keyword, or use externalizable, to be able to store/load the object properly).
Use serialization if possible, it saves you from inventing new+uncompatible mechanism of doing something in java.

Disadvantage of using change document

Hi all,
I am currently using triggering certain code (which is written in receiver fm in SWETYPV associated with an event) based on change documents using SWEC.
I just want to know are there any disadvantages associated with usage of change documents, creation of change document objects.
Pointers to any documentation on change documents would be helpful, I am aware on how to use change documents but I want to get in depth of what exactly happens behind the scenes.
Thanks.
кu03B1ятu03B9к

I dont find any disadvantages with change documents.
http://help.sap.com/saphelp_nw2004s/helpdata/en/2a/fa015b493111d182b70000e829fbfe/frameset.htm

HT201250 Is there any disadvantages to Time Machine? Why doesn't everyone get it?

I am looking at Time Machine, and it looks great and really helpful. Are there any disadvantages? Why would anyone not get it? I am trying to figure out if I am missing something. Thank you!

Unlike Mr. Galt, I don't use TM, preferring bootable clones made with Carbon Copy Cloner. Disadvantages?
1. not bootable, so useless if the boot volume goes south, without reinstalling the OS and hoping that restores the boot volume. Alternatively, you can wipe the boot volume, reinstall the OS, and hope the TM backup is restorable. Contrast with booting into a clone and immediately knowing if it works. If so, then you're back in business.
2. TM requires always having the ext HD connected and powered up. I prefer connecting ext FWHDs and updating clones on my schedule, not Apple;'s,
3, I've never had to retrieve something I changed or deleted, so TM holds no value for me.
To each their own. For more on TM vs clone, see http://pondini.org/TM/Clones.html
Finally, a google search for TM vs clone gives many hits. Peruse them.

Hover Top Level Navigation, any disadvantages?

Hello,
I am considering .<a href="http://help.sap.com/saphelp_nw04/helpdata/en/53/a16a3e54a2e946e10000000a114084/content.htm">Setting Hover Effect (help.sap.com)</a> in the TLN, but I want to know if anyone has discovered any disadvantages with doing this e.g degraded performance or any other things.
Best regards,
Joe

Dear Atul,
Thank you for your quick reply.
However, using horizontal-y is not serving my purpose. I want the functionality similar to that of the standard SAP TLN in case of the scrolling bar when the number of roles increase in TLN.
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Disha.

Disadvantages of using REFCURSORs from JDBC

Hi,
Normally I write my SQL statements from inside Java (eg PreparedStatements).
I am investigating on creating PL/SQL Packages, supplying procedures and methods, which I can call from Java using CallableStatements. I understand the advantages of having a layer/API on the database side.
For example: retrieve some records from a table. (the PL/SQL function getCustomers returns a REFCURSOR)
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- CallableStatement ("begin ? := getCustomers(); end;") -> cast getObject() to ResultSet -> loop ResultSet
What are the disadvantages of using the CallableStatement (REFCURSOR)?
Thanks, regards, Stephan

While that article may be a good intro for someone not familiar with JDBC it has some misinformation in it that can be misleading at best and cause performance and memory issues at worst.
Row-prefetching - there is little benefit to using a large value for this setting. As with most things extremes are to be avoided.
It is important to know how the data is going to be used. What is the point of bringing ALL the data from the DB in one call if you are going to write it to the file system. File I/O is generally the slowest part of an application.
It is also important that the code be scaleable. Apps should be written so that future modifications will impact existing functionality as little as possible. If you eat up the memory for one table or statement that limits the memory available for other uses. Worse, when things go wrong and you need to reduce the fetch setting you may now have problems everywhere because the testing you originally performed may have relied on that larger fetch setting.
If the data fetching is not done in its own thread then using a very large value can actually make an application appear to 'freeze' while it waits for the data fetch to complete.
A large fetch size can also waste significant amounts of memory; essentially allocating it but never using it and never allowing any other process to use it. This is because for a fetch size of 'n' Oracle has to allocate space for 'n' rows that are each of maximum size.
This wasted is most often due to the common VARCHAR2 datatype. Consider a single column defined as VARCHAR2(100). In the DB this column is stored as variable length. But Oracle will allocate 100 characters (could be multi-byte characters) in order to be able to hold a maximum length value.
If the actual data values never exceed 30 bytes then 70 bytes in each row are totally wasted. The more rows that are prefetched the more memory that is wasted simply in anticipation of a maximum length value that never occurs or only occurs rarely.
I've never used a prefetch/fetch size greater than one thousand and that was for tables with small records (no more than 10 or 20 columns).
And the Oracle docs don't even recommend a setting that high. See the JDBC Dev Guide
http://docs.oracle.com/cd/B19306_01/java.102/b14355/oraperf.htm#i1043756
>
Oracle Row-Prefetching Limitations
There is no maximum prefetch setting, but empirical evidence suggests that 10 is effective. Oracle has never observed a performance benefit to setting prefetch higher than 50. If you do not set the default row-prefetch value for a connection, then 10 is the default.

Disadvantages of Using BDCs in enhancements

Hi All,
Could anybody please tell me what are the possible disadvantages of using BDCs in a complex enhancement.
Thanks,
Anirban.

Hi,
One of the very common disadvantage of the BDC is that it doesnt take into account the configuration settings of the screen. Suppose you make any changes in the screen fields (e.g. you make some of the fields in the screen non editable or you make the fields invisible), in this case BDC will throw an error message beacuse the screen mentioned will now no more contain that field or the field will now no more will be an input field.
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Reward points if found useful
Mayank Agarwal

Disadvantages of using Oracle Coherence

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After going through the tutorial and leaning about Coherence, very much willing to go for it.
Although, don't know what are the disadvantages of using Coherence. Any suggestions?
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Some backgroung information on second-level caching can be found here: http://middlewaremagic.com/weblogic/?p=5407
Note that it discusses Hibernate, but it is applicable to every ORM framework.
When using a second-level cache the performance gain is had when the data is read-mostly (or even better reference data)
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cache, it may result in multiple redundant reads to the database.
- When an application writes directly to the database, concurrency concerns
are handled by the database, whether via optimistic or pessimistic locking.
When writing to a cache in memory, data integrity must be maintained via
some explicit concurrency control mechanism.
Coherence provides the following tools:
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using the ConcurrentMap API or optimistic updates using EntryProcessor
using the InvocableMap API.
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cache-aside solution, it also provides tools that enable much more efficient and
easier-to-implement persistence patterns. (http://middlewaremagic.com/weblogic/?p=5954)

Any disadvantages of using secondary IPs?

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