Checkpoint and SCN

Hi,
When executing below command, I found check point occur and SCN is changed...
alter system switch logfile;
While executing below commnd checkpoint is also ocuured but SCN not changed..
alter system checkpoint;
As both the execusion, checkpoint occur and SCN is written.. can anyone tell why this happened?
Can anyone explain the relationship between checkpoint and SCN?
Thanks,
Tina K.

Lets keep it simple and straight, SCN generate when ever there is change (ie change vector).
checkpoint -Simple write dirty block to datafile and update control file too.
( check point keep database safe(=easy recoverable )from instance failure , power failure..)
Just think u have 2 online redo logfile , you switch the logfile so all changes is there in logfile 1 is wriiten to datafile Right, now logfile 2 is current logfile and power went off. When u start again database oracle try to check/match SCN of all datafiles from control file , if any databfiles header has less SCN it will read chnage vector from online redo and apply chnages and update header.
SCN is base for all recovery and work around the change vector.
I know i am very poor in explaining things , if you want to know more insight story read book "Backup and Recovery by Rama -Oracle Press" it has very good details.
Cheer,
Virag Sharma
http://virag.sharma.googlepages.com/

Similar Messages

Motive of checkpoint and SCN using with DBWr and LOGWr processes ??

What checkpoint has to do with log writer process i am not getting exactly ?..
Like see i fire 1 update query and apparently it is generating some redo blocks which in turn will come to my redo log files now in tihs whole cycle where the checkpoint will occur and why??
1)My update query
2) take locks
3)generate redo
4)generate undo
5)Blocks are modified but they are still in redo log buffer...
now this blocks eventually comes to redo log files in this whole way where check pointing take place and why??
checkpoint also takes place when Datablocks are flushed to datafiles again the same reason why??
Same way around the same question the what checkpointing has to do with DBWr process also i am not clear...
Apart from this whole picture SCN is generated when user issue comitts..and we can say SCN can be used to identify that transaction is committed or not.?
So what is the motive of SCN to update in Control file...MAy b to get the latest transaction committed..??
Sorry one thread with so much questionss..but this all things are creating a fuzzy picture i want to make it clear thnx for your help in advance ..
I read documentation but they havent mentioned in depth for checkpointing..??
THANKS
Kamesh
Edited by: 851733 on Apr 12, 2011 7:57 AM

851733 wrote:
What checkpoint has to do with log writer process i am not getting exactly ?..And where exactly did you read that it has anything to do with it? How did you come up to the relation anyways? The time checkpointing would come into the play with the log files would be when there would be a log switch and this would induce a checkpoint, causing/triggering the DBWR to write the dirty buffers to the datafile and allowing the redo log group to be reused. That's about it.
Like see i fire 1 update query and apparently it is generating some redo blocks which in turn will come to my redo log files now in tihs whole cycle where the checkpoint will occur and why??
1)My update query
2) take locks
3)generate redo
4)generate undo
5)Blocks are modified but they are still in redo log buffer...
now this blocks eventually comes to redo log files in this whole way where check pointing take place and why??Read my reply above, at the time of writing the change vectors in the log file, there won't be any checkpointing coming into the picture.
checkpoint also takes place when Datablocks are flushed to datafiles again the same reason why??Wrong, the checkpoint event would make the dirty buffers written to the dataflile. Please spend some time reading the Backup and Recovery guide and in that, instance recovery section. In order to make sure that there wont be much time spent in the subsequent instance recovery, it would be required to move the dirty buffers periodically to the data file. THis would be caused by the incremental checkpoint . Doing so would constantly write the content out of the buffer cache thus leaving few buffers only as the candidate for the recovery in the case of the instance crash.
Same way around the same question the what checkpointing has to do with DBWr process also i am not clear...Read the oracle documentation's Concept guide again and again as long as it doesn't start getting in sync in with you(and it may take time). One of the events , when DBWR writes , is the occurance of the Checkpoint. Whenever there would be a checkpoint, the DBWR would be triggered to write the buffers (dirty) to the datafile.
Apart from this whole picture SCN is generated when user issue comitts..and we can say SCN can be used to identify that transaction is committed or not.? Not precisely since there would be a SCN always there , even when you query , for that too. But yes, with the commit, there would be a commit SCN that would be generated including a commit flag entered in the redo stream telling that the transaction is finally committed. The same entry would be updated in the transcation table as well mentioning that the tranaction is committed and is now over.
So what is the motive of SCN to update in Control file...MAy b to get the latest transaction committed..??Where did you read it?
Sorry one thread with so much questionss..but this all things are creating a fuzzy picture i want to make it clear thnx for your help in advance ..
I read documentation but they havent mentioned in depth for checkpointing..??
Read the book, Expert one on one by Tom Kyte and also, from documentation, version 11.2's Concept guide. These two would be more than enough to get the basics correct.
HTH
Aman....

Incremental checkpoint and SCN

Hi,
I am getting messages of incremental checkpoint in my alert logs with some scn.
>
Completed checkpoint up to RBA [0x125de6.2.10], SCN: 445135162445
>
Does this mean that all dirty blocks which have had their initial changes before this SCN(445135162445) will be written to disk so that instance recovery can begin from the SCN from which checkpoint has completed.Or is it the other way like the incremental checkpoint has occured at scn 445135162445.
Sekar

user13485610 wrote:
As per my knowledge, the checkpoint is classified as below (correct me if I am wrong somewhere)
Checkpoint types can be divided as INCREMENTAL and COMPLETE.
Also COMPLETE CHECKPOINT can be divided further into
PARTIAL and FULL.
It would be convenient to have a reference to the documents where you picked up this information. There may be further reading in them that clarifies the meaning. The terms have been around for a long time, of course, but it's always hard to get any sort of definitive description together - in your case, for example, you don't make any comment about which checkpoints lead to high priority writes and which to low, but the description of any type of checkpoint isi incomplete without some reference to the write priority.
As far as classifying checkpoints by name - I'm not too concerned that there is still some confusion in the different way that people name or categorise them, provided that they can describe what's going on to ensure that there is no ambiguity. In this context I think there are only options to consider:
a) does the particular type of checkpoint walk along the checkpoint queue (CKPTQ) in order to pick the blocks that need to be written to disc.
b) does the particular type of checkpoint use a different queue (such as an object queue or file queue) to pick the blocks that need to be written to disc.
c) is there any other mechanism for picking the blocks to be written - such as walking the LRU and identifying all dirty blocks.
To my mind, an incremental checkpoint should probably have a definition that says it walks the checkpoint queue.
I dislike the term "complete" if it then leads to the option for "partial" - how much clarity can you read into the statement "at this point Oracle does a partial complete checkpoint" (or should that be a "complete partial checkpoint") - but I can understand the need for a term of that sort to distinguish a checkpoint that is based on one of the other queues.
But my doubt is mentioned below.
2.At the time of log switch - Sometimes log switches may trigger a complete checkpoint , if the
next log where the log switch is to take place is Active.
Why is this behaves in this fashion? (Any internal thoughts on this please)This, in part, is why I'd like to see the reference document - I think that the term "complete" may have been given a different meaning at this point. If the logfile you want to use is still active checkpoint activity MUST take place urgently, but it need only be a checkpoint that walks the CKPTQ up to the point where the content of the target redo log can be discarded. This is no different from any other checkpointing due to log file switch - but it could have a higher degree of urgency. (The need to differentiate this special case on log file switch probably came about at the time that Oracle stopped triggering an automatic checkpoint at every log file switch.)
Regards
Jonathan Lewis

Checkpoint number and SCN number

Hi,
I am getting confused between these two terminology, i have asked a couple of people and every where i get different explanation.
Can anyone please clarify these -
a) Is checkpoint point number and SCN number same kind of number (SCN# will be greater than checkpoint#)?
b) I was told that checkpoint also gets incremented when log switch happens, but when I issue alter system switch logfile, the checkpoint_change# in v$database does not get incremented. It gets incremented when i issue alter system checkpoint
Thanks in advance
Neel

816153 wrote:
Thank you all.
Can someone help me understanding - why checkpoint_change# of v$database does not get incremented when i issue "alter system switch logfile"?
What do you think can be the reason? Let's hear from you first. And by the time you prepare the answer, please have a read of this pdf as well,
http://prutser.files.wordpress.com%2F2008%2F12%2Fcheckpointsukoug.pdf
HTH
Aman....

Why checkpoint increase SCN?

the database is not used now,and I uses command
"alter system checkpoint" repeatly,and every time
checkpoint,the SCN will increase,but there is nobody
using the database,and there is no transaction to
commit,why will SCN increase? From oracle doc,every
time commit,the SCN will increase,under what
situation will SCN alse increase?

under what situation will SCN alse increaseThe recovery process uses SCN to identify a particular state of the database.
Oracle sometimes says SCN stands for System Commit Number (e.g. error message for ORA-8209) but this is misleading because it can also be incremented by other things. These things are not well documented, but they seem to be related to recursive data dictionary SQL (which makes sense). One such is block cleanout. Another is checkpointing, as you've noticed. I believe activity by stuff like AQ, DBMS_JOB, etc will increment the SCN.
There is an aside in Metalink note #28929.1 which states rather tantalizingly:
In some situations, the SCN increment during startup may permit the database to open.
Does this mean STARTUP also increments the SCN? Something for me to test when I get home this evening.
Does anybody out there have a definitive list?
Cheers, APC

ARP table clash with checkpoint and ASA firewal issue

We are migrating DMZ segments from a checkpoint to a ASA 5585 firewall that we had connected to the same segments as the Checkpoint except on different IP addresses then the checkpoint interfaces. The Checkpoint interfaces are the default gateway for the servers. When I implemented the NATs entries below we experienced an arp table clash with the checkpoint and ASA firewall on the local segments that caused a application outage. What was determined was that the checkpoint firewall was showing that all the IP addresses in particular on vlan130 segment was associating the MAC address of the ASA interface instead of the real sever MAC address. I need assistance understanding the reason why the Checkpoint was pointing the ARP entries for many different address on VLAN130 to the ASA firewall MAC?
nat (any,internet-outside) source static any any destination static isxh2007_Xlate_167.9.6.21 isxh2007_10.121.201.86 unidirectional description To match chkpt NAT rule #5
nat (VLAN130,internet-outside) source static ISX_EDI_Hosts isxh2008_Xlat_167.9.6.22 unidirectional
nat (any,internet-outside) source static Private-Addresses ISX_OUTBOUND_NAT_167.9.6.1 destination static external_167.9.x external_167.9.x unidirectional
nat (any,any) source static Mars-Internal-All Mars-Internal-All destination static Private-Addresses Private-Addresses
nat (internet-dmz,internet-outside) source static acs-vmww2419.mars-ad.net acs-vmww2419_xlate_167.9.6.23
nat (internet-dmz,internet-outside) source static acs_vmww2420 acs_vmww2420_xlate_167.9.6.24
nat (internet-dmz,internet-outside) source static pass_reset_internal_10.121.201.50 pass_reset_external_167.9.6.25
nat (internet-dmz,internet-outside) source static HE-Portal-poland_10.121.120.10 ext_HE-Portal-poland_167.9.6.26
nat (any,internet-outside) source dynamic any ISX_OUTBOUND_NAT_167.9.6.1
isxasa04/wwy-legacy# sho interface
Interface TenGigabitEthernet0/8.129 "core-inside", is down, line protocol is down
MAC address 442b.0330.aba2, MTU 1500
IP address 10.121.129.X, subnet mask 255.255.255.0
Traffic Statistics for "core-inside":
241633 packets input, 12094352 bytes
44788 packets output, 3032584 bytes
109732 packets dropped
Interface TenGigabitEthernet0/9.130 "VLAN130", is down, line protocol is down
MAC address 442b.0330.aba3, MTU 1500
IP address 10.121.130.X, subnet mask 255.255.255.0
Traffic Statistics for "VLAN130":
1264203 packets input, 136452168 bytes
326080 packets output, 69216516 bytes
794035 packets dropped
Interface TenGigabitEthernet0/9.136 "VLAN136", is down, line protocol is down
MAC address 442b.0330.aba3, MTU 1500
IP address 10.121.136.X, subnet mask 255.255.255.0
Traffic Statistics for "VLAN136":
374547 packets input, 23696109 bytes
51186 packets output, 3324895 bytes
173500 packets dropped
Interface GigabitEthernet0/1 "internet-outside", is down, line protocol is down
MAC address 442b.0330.ab9b, MTU 1500
IP address 167.9.6.X, subnet mask 255.255.255.0
Traffic Statistics for "internet-outside":
352158 packets input, 17245425 bytes
76888 packets output, 3872904 bytes
12255 packets dropped
Interface GigabitEthernet0/2 "internet-dmz", is down, line protocol is down
MAC address 442b.0330.ab9c, MTU 1500
IP address 10.121.201.X, subnet mask 255.255.255.0
Traffic Statistics for "internet-dmz":
237795 packets input, 12460108 bytes
40787 packets output, 2775684 bytes
27378 packets dropped
Interface GigabitEthernet0/4 "VLAN140", is down, line protocol is down
MAC address 442b.0330.ab9e, MTU 1500
IP address 10.121.140.X, subnet mask 255.255.255.0
Traffic Statistics for "VLAN140":
386931 packets input, 18807725 bytes
48936 packets output, 3319712 bytes
114417 packets dropped
We crosschecked MAC addresses and this is what we found:
Checkpoint ARP table:
10.121.130.101 44:2b:3:30:ab:a3 3285
ASA ARP table:
isxasa04/wwy-legacy# sh arp | i 10.121.130.101
VLAN130 10.121.130.101 001a.4b06.dd45 10525
Server real address provided by processing:
0x001A4B06DD45
When we saw that the Checkpoints had a different/wrong entry we shut down all the physical ports on the new ASAs (except for failover and management);
Kevin cleared the ARP table on the Checkpoints and problem was solved;
Later I saw this:
isxasa04# sh int | i MAC
MAC address 442b.0330.ab9a, MTU not set
MAC address 442b.0330.ab9b, MTU not set
MAC address 442b.0330.ab9c, MTU not set
MAC address 442b.0330.ab9d, MTU 1500
MAC address 442b.0330.ab9e, MTU not set
MAC address 442b.0330.ab9f, MTU not set
MAC address 442b.0330.aba0, MTU not set
MAC address 442b.0330.aba1, MTU not set
MAC address 442b.0330.ab98, MTU not set
MAC address 442b.0330.ab99, MTU not set
MAC address 442b.0330.aba2, MTU not set
MAC address 442b.0330.aba3, MTU not set

The Asa is proxy Arping those macs. Turn off proxy arp and put in static arp entries until you completely shut down the checkpoint.
Sent from Cisco Technical Support iPad App

What is the difference between full checkpoint and incremental checkpoint?

What is the difference between full checkpoint and incremental checkpoint?
And what is checkpoint queue?
Can someone clarify these concepts?
Thanks!

Hi,
there are different types of checkpoints:
- Full checkpoint:
=> DBWR writes all dirty buffers from the Buffer cache to the datafiles and CKPT retrieves a new Checkpoint Change Number from a sys owned sequence and writes this number to all file headers and the controlfile.
-- can be triggered by different events, like a logswitch, a manual checkpoint (alter system ..), a shutdown and so on
This is the setup point for SMON for a crash recovery.
- Partial checkpoint:
=> DBWR writes all dirty buffers of a singel tablespace from the Buffer cache to the datafiles and CKPT retrieves a new Checkpoint Change Number from a sys owned sequence and writes this number to all file headers and the controlfile.
-- can e triggered by an ALTER TABLESPACE OFFLINE, ALTER TABLESPACE READ ONLY, ALTER TABLESPACE BEGIN BACKUP statement.
Incremental checkpoint:
number to all file headers and the controlfile.
-- can be triggered by different events, like a logswitch, a manual checkpoint (alter system ..), a shutdown and so on
- Partial checkpoint:
=> DBWR writes all dirty buffers of a single tablespace from the Buffer cache to the datafiles and CKPT retrieves a new Checkpoint Change Number from a sys owned sequence and writes this number to all file headers and the controlfile.
-- frequency is determined by FAST_START_MTTR_TARGET parameter (new feature to Oracle 9i), with wich you can specify a time in seconds which SMON is allowed to take maximal for a Crash Recovery until the database must be open again.
Dapending on the system you have SMON must calculate the maximum number of Redolog-blocks which it can manage to recover in the specified number of seconds. It will then create so called incremental checkpoints which will be tracked in the so called checkpoint queue in memory.
FAST_START_MTTR_TARGET is auto-tuned in Oracle 10g and Oracle tries to manage (incremental) checkpoint in a fashion that a minimum of I/Os are caused and a minimum time for crash recovery is needed.
If you set LOG_CHECKPOINTS_TO_ALERT to TRUE you will find checkpoint information in the alertSID.log file. You will see FULL and INCREMENTAL checkpoints then.
Hope this clarifies your question,
Lutz Hartmann

Checkpoints and Logging

I just had a general question regarding SSIS performance.
I've got a good number of SSIS packages that comprise one master package. I've just implemented checkpoints and logging on each package.
In the past, the master package took around 30 minutes to run. Now with logging and checkpointing in place, it takes 45 minutes!
Do checkpoints and logging add that much more processing time to packages?? That's an increase of 50%...
Has anyone else seen this type of behavior?
Thanks!
A. M. Robinson

Hi Ansonee,
Here is another custom restart pattern of SSIS pacakge that you can refer to:
http://www.mssqltips.com/sqlservertip/2959/sql-server-integration-services-package-restartability/
Regards,
Mike Yin
If you have any feedback on our support, please click
here
Mike Yin
TechNet Community Support

Checkpoint and commit

Does commit causes checkpoint?If not so how committed data will be written immediately to data file and available to other user?
According to Oracle document Committed data will be saved in datafile and updated with latest SCN in datafile header files on checkpoint.Checkpoint will generate only for the fallowing condition,
1.logswitch
2.log_checkpoint_interval and time
So Data will not be saved immediately to datafile with latset SCN.My doubt is How other user will be able to get latset infomation immediately if logswitch and interval time takes long time.

Tthank you for reply.
"A block will not be voluntarily removed from memory
unless it is safely stored on disk. That will be done
in conjunction with a checkpoint."
Does it mean that Only committed data will be
written(not saving) to Datafile.No. That does not mean 'only committed data will be on disk'.
It means that the data block will not be removed from memory until it has been written to disk.
I know that only Committed data will be saved into data files.
My doubt is will committed and un committed data will both written to datafiles.Why can uncommitted blocks NOT be on disk?
If we allow uncommitted blocks to be written, in an 'emergency' we could take block 'A' that is currently dirty but uncommitted, and put it on disk.
If the user then says 'commit', at some time we would simply need to mark that block free-of-transaction. Since that is done by the next access to the block, and not by the commit process - the transaction has been marked complete in the rollback, and the next process to check whether the current block is in a transaction can clear that information - the current committing process does not care whether the block is in memory or on disk.
If a user says 'rollback', the dirty block can be re-read from disk and the rollback information - which might also have been moved to disk and might require a separate read - can be used to restore the block to the 'undo' state.
If, in the mean time, another user wants to see the block. It's on disk. User's process grabs the block and puts it into buffer cache. Notices that the block is involved in a transaction and creates a CR block.
The above assumes Buffer Cache pressure and needs to be cleaned to make room.
Now, let's think ahead a bit, from a performance perspective. If, during a checkpoint, we allow the system to write uncommitted information to disk (even through we have enough Buffer Cache), then the amount of stuff that would need to be recovered [take a clean block, apply redo] from the redo logs would be minimized as well. The real work would then be reduced to little more than checking whether the transaction is marked as committed or rolled back.
See also http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:618260965466
Bottom line - the DBWR does not know, or (as far as I know) care, whether a block contains committed data.
(Question to self - DBWR never writes CR blocks to disk [pretty sure<g>]. Does it actually see CR blocks and ignore them, or does it simply not see the part of the chain that contains CR blocks? )

Header datafile and SCN

Hi every body,
The controlfile contains the current SCN and the checkpoint SCN. that is right ?
In my search, I found that every datafile online and in read write mode, contain in his header the scn checkpoint.
But, I think that it contains only the last scn applied to this datafile. that is right?
Without this last scn in the datafile, how oracle know when he is stopped writing to the datafile in case of failure, to recover it ?
Thank in advance for your answers.

user622061 wrote:
Thank you a lot for the links.
I did a test :
BEFORE TEST
v$database :
CHECKPOINT_CHANGE# CURRENT_SCN
13114719 13117108
v$datafile :
NAME CHECKPOINT_CHANGE# LAST_CHANGE#
C:\ORACLE\ORADATA\BDD10G\TBS1_01.DBF 13117132
v$datafile_header :
NAME CHECKPOINT_CHANGE# LAST_CHANGE#
C:\ORACLE\ORADATA\BDD10G\TBS1_01.DBF 13117132
v$logfile and v$log :
MEMBER STATUS
C:\ORACLE\ORADATA\BDD10G\REDO01.LOG INACTIVE
C:\ORACLE\ORADATA\BDD10G\REDO02.LOG CURRENT
C:\ORACLE\ORADATA\BDD10G\REDO05.LOG UNUSED
TEST
create table toto ( a varchar2(30)) tablespace tbs1 ;
insert into table toto values ('SEBASTIAN');
commit;
AFTER TEST
v$datafile :
NAME CHECKPOINT_CHANGE# LAST_CHANGE#
C:\ORACLE\ORADATA\BDD10G\TBS1_01.DBF 13117132
v$datafile_header :
NAME CHECKPOINT_CHANGE# LAST_CHANGE#
C:\ORACLE\ORADATA\BDD10G\TBS1_01.DBF 13117132
the checkpoint_change# for this datafile is the same, before and after insert and commit a data in this tablespace.That's correct! The reason for this is that Oracle won't go and ask DBWR to write into the datafile with each and every commit of yours. You have ended a transaction, that's all! Now, the results of that transaction is updated already by LGWR into the redo log file. The checkpoint number(not SCN) is not updated by DBWR since this would happen in the case it would do a full Checkpoint.
To inspect the contents of this datafile, I use some OS commands : I search the word "SEBASTIEN" !
The first time, I didn't find it.
few minutes later, I found the word "SEBASTIEN" --> So my datafile is updated by the insert I did.Correct again! DBWR would write when it would think it's good to write. So not at the time of commit but after some time, DBWR updated the contents into the datafile.
But, the problem is that his checkpoint_change# still the same = 13117132As I have explained , it won't change, not so quickly.
>
>
You can reproduce the test !
My problem is to understand how Oracle ( DBWR) can update a datafile with data related to the SCN newer than the SCN registered in the header of datafile ?DBWR would have the list of the dirty buffer's list with it which it would periodically. If there is a commit and the data is updated in the logfile, the contents logged into the redo log file would be checkpointed in thedatafile after some time. This commit event, stored in the log file, is also recorded inthe control file. That's how Oracle knows, in the event of a crash, that to what extent they have to do the recovery since the stop checkpoint is already noted in the controlfile.
If Oracle did it, how can he know the last SCN on every datafile.It doesn't need to. Control file has it.
HTH
Aman....

How to find the timestamp and SCN in the standby database?

Hai,
I have Oracle 9.2.0.4 RAC with 2 nodes in the production. The logs generated at these servers will be manully moved to my standby database and will be applied. To know what isthe maximum log files applied in the standby database, i am using the below mentioned query in the standby database,
Select thread#,max(sequence#) from v$log_history group by thread#
In general i am using "recover standby database until cancel" command and then checking the database with the above mentioned query whether all the logs are applied or not.
If i use time based or scn based recovery in standby database i.e., "recover standby database until time <time>" or "recover standby database until change <scn number>" , after completion of the recovery, apart from the message "Media recovery complete" or by seeing the alert log, is there any way to query the standby database, so that i can identify the time or scn upto which the archived redo log files got applied.

Hi Sridhar,
There should be some view which will have applied_scn information. There is one more option i can suggest, you can create a heart beat table in production with 2 column like scn and timestamp. Update this table every minute. From standby db you can query this table and get fair idea on applied_scn and timestamp.
While exporting you can export using flashback_scn by taking the value from heartbeat table of standby.
This heartbeat table is used very common in streams environment. Just see if this helps you.
hth,
http://borndba.com

RADIUS and CHECKPOINT and NORTEL

I have installed the NMAS modules from Border Manager 3.8 onto a Netware 6 SP3 box. I installed per TID 10078616 and can authenicate from my W2K workstation fine.
I am now trying to authenicate from a Nortel switch and a VPN from a checkpoint firewall. So far I have installed all of the login methods and I still get an unknown RADIUS client on the RADIUS server, when loging in from the Nortel switch. I have not tried to authenicate from the checkpoint firewall yet.
Does anyone have pointers as to the configuration to use the RADIUS server with Nortel or Checkpoint or a pointer to a technical description of the various login methods?
John

John,
I have a very similar problem with our 3com switches, can you give me more
details of what you did to get it working?
Thanks a lot,
Matt Hudson
(CNE6.5)
"John Curran" <[email protected]> wrote in message
news:[email protected]...
> Thank you very much, Jordack. The instructions were clear and concise.
>
> We go the Checkpoint firewall to authenicate VPN's with the RADIUS server.
>
> Also, I got the information from Nortel to allow authenication. I had to
> set up the Radius server to allow Service-Type Administrative and
> Service-Type NAS-Prompt. Then I had to go into each user and set up
> one of the service types.
>
> Thanks for your help.
>
> John
>
>
> >>> Jordack<[email protected]> 01/26 9:36 AM >>>
> I uploaded a quick draft guide. It should help.
>
> http://www.thiscorner.com/guides/cp-radius.pdf
>
> Jordack
>
> "John Curran" <[email protected]> wrote in message
> news:[email protected]...
> > Thanks for the input. I will get that book.
> >
> > With the Nortel switch it is curious. I had forgotten to add the switch
> > to the client list. When I did, the radius server accepts the
> > authenication and sends an accpt message, but the Nortel switch says
> > access denied. I put a Sniffer on the link and the accept message looks
> > just like any other accept message (follows RFC 2865). I have a feeling
> > Nortel does not follow RFC 2865 or does not like the authenication ID
for
> > some reason. I guess I will have to work more with Nortel to resolve
that
> > one.
> >
> > John
> >
> >
> >>>> Jordack<[email protected]> 01/26 7:53 AM >>>
> > Sorry about not responding, I saw your post and meant to dig up my
notes
> > and respond.
> >
> > I don't know much about the Nortel stuff.
> >
> > Make sure you have added the IP address of your Nortel and Checkpoint
box
> > to
> > the 'Clients' page of the 'Radius:Dial access System". The DAS will
only
> > except connections from known clients. From the sounds of it that might
> > be
> > the issue.
> >
> > For the CheckPoint Setup stuff there is a few things you will need to do
> > on
> > the Checkpoint Box.
> >
> > I used this book http://www.syngress.com/catalog/chapter.cfm?pid=25903
and
> > Everything worked.
> >
> > I was working on a small guide for CheckPoint radius but got pulled to
> > other
> > things. If I get it finished Ill post it
> >
> >
> > "John Curran" <[email protected]> wrote in message
> > news:[email protected]...
> >>I have installed the NMAS modules from Border Manager 3.8 onto a Netware
6
> >>SP3 box. I installed per TID 10078616 and can authenicate from my W2K
> >>workstation fine.
> >>
> >> I am now trying to authenicate from a Nortel switch and a VPN from a
> >> checkpoint firewall. So far I have installed all of the login methods
> >> and
> >> I still get an unknown RADIUS client on the RADIUS server, when loging
in
> >> from the Nortel switch. I have not tried to authenicate from the
> >> checkpoint firewall yet.
> >>
> >> Does anyone have pointers as to the configuration to use the RADIUS
> >> server
> >> with Nortel or Checkpoint or a pointer to a technical description of
the
> >> various login methods?
> >>
> >> John
> >>
> >
> >
> >
> >
>
>
>
>

Oracle Checkpoint and task of DBW0/LGWR

Hi All,
I am a bit confused about the working of DBW0 and LGWR processes.
"A checkpoint performs the following three operations:
Every dirty block in the buffer cache is written to the data files. That is, it synchronizes the datablocks in the buffer cache with the datafiles on disk.
It's the DBWR that writes all modified databaseblocks back to the datafiles. "
I know this is very basic question and have read many documents about this.
But my question is,if DBW0 itself writes the blocks to disk(datafiles) then what is the task of LGWR ( writing from redo log buffer to online redo log and then to datafiles).Online redo logs will store all modified (committed) redo records and will flush the contents to datafile at some interval.Then isnt the same task performed by DBWR???
Thanks,
Aashish S.

Hi Aashish
Redo consists of only the specific changes made to a (say) data block and the necessary overheads to clearly "date" and identify it. So this is the bare minimum required for recovery purposes and the bare minimum that needs to be written to disk to ensure committed data is "safe" and protected.
Oracle writes this information into a special area of memory (log buffer) and the LGWR's job is focused on purely on writing this out to disk as necessary.
The actual "full" BIG blocks themselves therefore can generally stay in the buffer cache(s) and Oracle generally doesn't have to worry about writing changes to these blocks to disk as it's a somewhat significant overhead to do so and is generally only necessary when it needs to clear out space for new blocks. Transactions are safe, the redo being written to disk ensures that.
These blocks include the "BIG" undo blocks as again, they're generally only needed for the general running of the database (rollback/read consistency) and generally only get written to disk when space is an issue.
Oracle wants to delay and avoid writing the full blocks/buffers to disk (task of DBR0) as much as possible.
Oracle needs to write the redo to disk much more often to protect committed changes.
I probably just confused you more !!
Cheers
Richard Foote
http://richardfoote.wordpress.com/

Checkpoint and ASA

Inside I have 2 networks: 10.10.x.x and a 10.199.x.x
My ASA interfaces was the following:
E0/0 Public IP
E0/1 10.199.1.2/24
E0/2 10.10.144.47/22
I put a checkpoint in front of the ASA and changed to the following:
Checkpoint Ext. 10.10.144.47/22
Checkpoint Int. 192.168.1.1/30
ASA E0/1 10.199.1.2/24
ASA E0/2 192.168.1.2/30
Now I am having trouble talking between the networks 10.199.x.x and 10.10.144. x
I have attached ASA config.
Thanks in advance on any help provided

Hi,
So if I am looking correct then the "insideNOV" interface leads to the Checkpoint which has the other LAN network behind it?
The interface ACL for the interface is not really clear to me as it contains a lot of "name" and "object-group" references which are not mentioned. It seems though that on multiple occasions you have referenced the NOV network as the destination. Should this not be the source network as that network is located behind that interface?
Also with regards to the routing you have only shared your Default Route in the configuration.
Do you have a route for the NOV network towards "insideNOV" ?
route insideNOV 10.10.144.0 255.255.252.0 192.168.1.1
Does the Checkpoint have the appropriate routing and other configurations to allow the traffic?
- Jouni

CheckPoint and Instance Recovery

hi,
what is checkpoint Exactly.How it will Preform Instance Recovery.
thanks
with Regards

hi,
thanks for reply.I read the documents and books,but i am not clear Exact point so that i have been posting here.
for example
semantic checking
Twq User a,b.Both of them has Emp tables but different Columns.
user A
select * from Emp;
User B
select * from Emp;
here i have doubts after B executing the query. how oracle take this, i think is it Semantic.
I am n't going to learn without Meaning a single word....
some terms not understanding so i am posting here
thanks
with regards

Checkpoint and SCN

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