Archive for March 2013

19 March 2013

Storage Area Networks SAN basic L1 and L2 interview question and answers

11:11 6 Comments
Storage Area Networks (SAN) has huge requirements and the popularity and importance of this technology is increasing every year. According to my knowledge EMC and IBM are good among this technology and they recruit lots of junior level SAN administrators. 

 In this post I have posted some of the basic SAN interview questions collected from various candidates. This should really help the SAN newbies....The best practise is always try to research and find out your own answers and not relying on someones answers....

SAN Storage Administrator L1 Interview Question and Answers

1. What is a SAN?
A SAN is a dedicated network for sharing storage resources. A SAN provides accelerated data access and supports advanced storage management.

2. Name 3 Limitations of DAS Technology?
No scalability, I/O Bottleneck, Limitations in cable length, Unable to share resource

3. Name at least 4 of the Hardware component in a SAN?
Cable, SAN Switch, GBIC, Storage Subsystem, Host Bus Adapters

4. How could implementation of a SAN benefit LAN performance?
High Speed, Long distance, Data Travel with in the SAN, Fast access Data Backup, Improved Performance

5. Name 3 key features of Fibre Channel?
High Speed, Long distance, Data Travel with in the SAN, Fast access Data Backup, Improved Performance.

 Also Read: Storage Area Network (SAN) Basic Free Tutorials

6. How is a SAN Superior to SCSI?
SAN offers a number of advantages to parallel SCSI. Fibre Channel is substantially faster than parallel SCSI. In addition, Fibre Channel supports both Fibre Optic and copper cabling at distances of up to 10 Kilometers. It also connects up to 127 nodes on an Arbitrated Loop and up to 16 million nodes on a Fibre Channel Switch. With its ability to map IP, Fibre Channel is significantly more than a parallel SCSI replacement. Fibre Channel’s IP support gives its networked storage devices access to multiple servers or nodes for accelerated data access and enhanced data management.

7. What is a Point-to-Point Topology?
Point-to point topology provides a simple, direct connection between just two nodes. This topology is the closest approximation to the traditional SCSI topology and provides a direct connection between two nodes, such as between a file server and a disk subsystem. With this topology, the transmitter port on one node os connected directly to the receiver port on the other node.

8. What is FC-AL?
FC-AL is a abbreviation for Fibre Channel – Arbitrated Loop. FC-AL is a industry standard topology that links up to 126 ports together on a single shared simplex media. Transmissions can only occur between a single pair of nodes at any given time. Arbitration is the scheme that determines which node has control of the loop at any given moment.

9. What is Switched or Switched Fabric Topology?
A Fibre Channel Switch permits multiple simultaneous transmissions between pairs of nodes connected to it. The data is switched from the source node to the destination node.

10. What is the “Fabric” in a Switched Fabric Topology?
In the early days of Fibre Channel, the concept of a universal “Fabric” was used to support Fibre Channel’s topology independence. With the advent of point-to-point and FC-AL topologies, it’s value has been enhanced.The Fibre Channel Fabric was designed as a generic interface between each node and the physical layer interconnection of the nodes. By adhering to this interface, any Fibre Channel node could communicate over the “Fabric” without having to know the interconnecting scheme between nodes. A “Fabric” is similar to a telephone switch which allows you to originate a call to another party without requiring you or the other party to have detailed information about the interconnection mechanism used to establish the call between two points.

11. Where does SAN fit into Today’s Networking Environment?
SANs compliment today’s LAN and WAN technologies by acceleration functionality and performance behind the server, where current LAN and WAN technology leaves off. They also compliment the ongoing advancements in LAN and WAN technologies by extending the benefits of improved performance, topological flexibility and remote management from the client and backbone to servers and storage.

Unlike traditional LAN and WAN technologies, the gigabit speed of a Fibre Channel-based SAN accelerates I/O performance, relieving the burden from servers in the tiered client/server architecture. SANs also support advanced storage management features that include highspeed remote back-up and data mirroring. They also provide a platform for server clustering to migrate into the open market.

 Also Read: DAS vs SAN vs NAS

12. What type of san switch you are using?
Brocade, Mc Data, so on

13. What is the command to measure the speed of the port?
      #show port 2

14. What you mean by lun masking?
Hiding the luns to specific to host

SAN Storage Administrator L2 interview question and answers:

1. What is the difference between Raid 1 and Raid 5?
 Mirroring and Parity striping across the disks.

2. What is the difference between Lun masking and Zoning?
Lun masking is hiding the LUN to specific server or Host and Zoning is specific to Operating system for e.g Windows zoning, UNIX zoning only preferred luns can be assigned to particular Zoning

3. Give examples of few CLI commands of the Storage controller?
Different for Different storage

4. What is the meaning of IOPS? Where it plays important role?
IOPS INPUT OUTPUT PER SECOND One transaction to and fro of the server to storage. Mission critical applications planning based on IOPS one can determine the storage,space needs.

 Also Read:  AIX Basic concepts and commands

5. Give an example of the Database configurations for Disk layout?
It differ storage to storage expected answer Raid 1+0 configurations

6. Name at least 3 ways consolidating storage improves operational efficiencies. ?
Centralized administration, Scalability, Backup/restore improvement

7. What advantages do LAN-free back up and restore deliver?
Speed up the backup/Restore, Data will not travel over LAN

8. Name at least 3 ways a SAN provides a High Availability Infrastructure.
No single point of failure, BACKUP/Restore speed, Replication/DR will be improved from Distance point of view

9. What are the steps involved to accomplish Raid best configurations?
Size of the data, no of users, criticality of applications, cost effective of the storage requirements, Raid 1+0

10. What is the functionality of multi pathing?
Load balancing, fail over on different path, security

13 March 2013

Tivoli Storage Manager interview questions by IBM

02:48 3 Comments
In this post am sharing the Tivoli Storage Manager TSM interview questions asked to my friends. these questions cover both TSM version 5.6, 6.X and V7. 

 Sorry, I was bit lazy and also busy to correct the spelling and grammatical mistakes. I have copied from my mail and pasted them directly here. Please dont mind and ALL THE BEST for your interview........

 Also Read: What is Offsite Reclamation ?

 Candidate 1:
  • Tell me about yourself?
  • Could u explain policymanagment?
  • Could u explain storagepool  hierarchy?
  • Explain drm process?
  • What are all the concepts covered in aix in training?
  • What is the use of RESOURCEUTILIZATION parameter?
  • What are all the pre-requisites before installing storageagent on client mechine?
  • Which purpose we are using CFGMGR command?
  • How transations are committed to recoverylog in 6.3?
  • What are the new features in tsmserver6.3?
  • In myenvironment copyg parameters set as VEREXITS=30 VERDELETE=30 RETEXT=NOLIMIT RETONLY=NOLIMIT,every day we take incremantal bakup after 31 day i want to resoter first day of version?    is it possible or not?
  • I forgot to take db backup, suddenly archivelog and archivefailoverlog got full , in this situation how do u handle?
  • How u restore sqldb?
  • Sqldb is online and mounted at that situation,if someone trying to backup,is it backedup or not?
  • I configured tdp for oracle on san environment,the storage pool is diskpool in local system,which is not in san zoning.then data goes through lanfree or lan?
  • Have u performed TSM multipule restores at a time?
  • Which fiberchannel connected to ur system ,how we check ?
  • Different types of client backups?
  • Difference bitween normalbackup and archivebakcup?
Also Read: Understanding Management Class Binding and Management Class Rebinding

Candidate 2:

1. Tell me about yourself?

2. Tell about your traning setup?

3. What are the topics you coverd in traning?

4. Storage hirarcy? (Expalin about all Stg pools types and data flow)

5. Explain Policy mgmt in detail?

6. Explain about copy group parameters?

7. Explain DRM?

8. Information flow in TSM 6.X version?

9. Difference betweem TSM 5.X and 6.X?

10.How to install TSM 6.3 on AIX?

11.LAN FREE COnfigaration?

12.Explain Mgmt Binding and Client option set in detail?

13.In which case you using mgmt binding and client option set?

14.TDP Domino and TDP SQL Configaration?

15.Which tape device driver installed in aix?

16.Some commands in AIX?

17.What is defalut VG in AIX?

 Also Read: 200+ TSM Interview Question & Answers to crack any interview

 Candidate 3:


1. TELL ME ABOUT YOURSELF?

2.DIFFERENCES BETWEEN 5.5 AND 6.3?

3.EXPLAIN ACTIVE LOG,ACTIVE MIRROR LOG,ARCHIVE LOG,ARCHIVE FAILOVER LOG IN 6.3?

4.WHAT  ARE THE PRE-REQUISITES FOR LANFREE?

5.HOW  TO CHECK THE OS LEVEL ERRORS IN WINDOWS AND AIX?

6.IS THERE ANY DATABASE MIRROR LOG FOR 6.3?

7.EXPLAIN YOUR PRESENT LIBRARY ENVIRONMENT?

8.HOW TO CHECK THE DEVICE INFORMATION IN AIX?

9.WHY YOU CAN USE THE RMAN SCRIPT IN TDP ORACLE?

10.WHICH DEVICE DRIVERS YOU CONFIGURED IN YOUR ENVIRONMENT?

11 March 2013

Use TXNGROUPMAX server option to send multiple files in a single transaction

23:55 No Comments
A transaction is defined as the unit of work exchanged between the client and server. The log records for a given DB transaction are moved into stable storage when the transaction is committed. The database information that is stored on disk remains consistent because the server ensures that the recovery log records, which represent the updates to these database pages, are written to disk.

 During restart-recovery, the server uses the active and archive log information to maintain the consistency of the server by redoing and, if necessary, undoing ongoing transactions from the time that the server was halted. The transaction is then committed to the database.

 Transaction commit is a function of all the log records for that transaction being written to the recovery log. This function ensures that the necessary redo and undo information is available to replay these transaction changes against the database information.

How TXNGROUPMAX Server Option works

The client program can move multiple files or directories between the client and server before it commits the data to server storage.

 A transaction that contains multiple files or directories is called a transaction group. Using the TXNGROUPMAX server option, you can specify the number of files or directories that are contained within a transaction group. You can use the TXNGROUPMAX option to increase performance when Tivoli® Storage Manager writes to tape. This performance increase can be considerable when you transfer multiple small files.

 Also Read: How TSM Server determines the eligibility of files during different types of backup ?

 If you increase the value of TXNGROUPMAX by a large amount, monitor the effects on the recovery log. A larger value for the TXNGROUPMAX option can have the following impact:

  • Affect the performance of client backup, archive, restore, and retrieve operations.
  • Increase utilization of the recovery log, as well as increase the length of time for a transaction to commit.

Also consider the number of concurrent sessions to be run. It might be possible to run with a higher TXNGROUPMAX value with a few clients running. However, if there are hundreds of clients running concurrently, you might need to reduce the TXNGROUPMAX to help manage the recovery log usage and support this number of concurrent clients. If the performance effects are severe, they might affect server operations. 

 The following examples show how the TXNGROUPMAX option can affect performance throughput for operations to tape and the recovery log

  • The TXNGROUPMAX option is set to 20. The MAXSESSIONS option, which specifies the maximum number of concurrent client/server sessions, is set to 5. Five concurrent sessions are processing, and each file in the transaction requires 10 logged database operations. This would be a concurrent load of:
20*10*5=1000


 This represents 1000 log records in the recovery log. Each time a transaction commits the data, the server can free 200 log records.

  • The TXNGROUPMAX option is set to 2000. The MAXSESSIONS option is set to 5. Five concurrent sessions are processing, and each file in the transaction requires 10 logged database operations, resulting in a concurrent load of:

2000*10*5=100 000

This represents 100 000 log records in the recovery log. Each time a transaction commits the data, the server can free 20 000 log records.

 Also Read: TSM Server Performance Tuning Parameters

Over time and as transactions end, the recovery log can release the space that is used by the oldest transactions. These transactions complete, and the log space usage increases.
Based on the previous two examples, five concurrent transactions with a TXNGROUPMAX setting of 2000 consume much more space in the recovery log. This increase in log space usage also increases the risk of running out of recovery log space.

The following table shows a comparison of the examples of the preceding TXNGROUPMAX settings. This example becomes more significant if a given log record takes 100 bytes.
Example of log bytes that are consumed by five concurrent sessions
TXNGROUPMAX SettingNumber of Log Bytes Consumed
TXNGROUPMAX=20100,000
TXNGROUPMAX=200010,000,000

You can use several server options to tune server performance and reduce the risk of running out of recovery log space:
  • Use the THROUGHPUTTIMETHRESHOLD and THROUGHPUTDATATHRESHOLD options with the TXNGROUPMAX option to prevent a slower performing node from holding a transaction open for extended periods.
  • Increase the size of the recovery log when you increase the TXNGROUPMAX setting.
Evaluate the performance and characteristics of each node before increasing the TXNGROUPMAX setting. Nodes that have only a few larger objects to transfer do not benefit as much as nodes that have multiple, smaller objects to transfer. 

 Also Read: How to increase TSM restore performance

 For example, a file server benefits more from a higher TXNGROUPMAX setting than does a database server that has one or two large objects. Other node operations can consume the recovery log at a faster rate. Be careful when increasing the TXNGROUPMAX settings for nodes that often perform high log-usage operations. The raw or physical performance of the disk drives that are holding the database and recovery log can become an issue with an increased TXNGROUPMAX setting. The drives must handle higher transfer rates to handle the increased load on the recovery log and database.

You can set the TXNGROUPMAX option as a global server option value, or you can set it for a single node. For optimal performance, specify a lower TXNGROUPMAX value (between 4 and 512). Select higher values for individual nodes that can benefit from the increased transaction size.

Temporary log files (RstDbLog and Failarch) in IBM TSM

23:51 No Comments
A database backup includes a database image and associated recovery-log files. During a database restore, the recovery-log files are temporarily stored in a subdirectory called RstDbLog. Log files that are created during day-to-day operations and that cannot be stored in the active log directory or in the archive log directory can be temporarily stored in a subdirectory called failarch. 

RstDbLog and Failarch Overview

To specify the location of subdirectories RstDbLog and failarch, use the ARCHFAILOVERLOGDIRECTORY server option. The Tivoli Storage Manager server creates the RstDbLog and failarch subdirectories in the directory that is specified by the server option. If you use this method, use a file system that is different from the file system that is specified by the ACTIVELOGDIRECTORY and ARCHLOGDIRECTORY parameters. 

 If you do not set the ARCHFAILOVERLOGDIRECTORY option, the Tivoli Storage Manager server creates the RstDbLog and failarch subdirectories automatically in the directory that is specified for the ARCHLOGDIRECTORY parameter on the DSMSERV FORMAT or DSMSERV LOADFORMAT command. You must specify the ARCHLOGDIRECTORY parameter for these commands.
  • Instead of using the server option to specify the location of the subdirectories, you can use the ARCHFAILOVERLOGDIRECTORY parameter in the DSMSERV FORMAT or DSMSERV LOADFORMAT command.
  • Consider using the ARCHFAILOVERLOGDIRECTORY server option or parameter to specify the location of RstDbLog and failarch subdirectories in a dedicated archive-failover-log directory, rather than allowing the server to automatically create the two subdirectories under the archive log directory. If the archive log directory becomes full, it can limit the amount of space that is available for archived log files. If you must use the archive log directory, consider increasing its size to accommodate both the RstDbLog and failarch directories.
For a database restore operation, you can specify the location of the RstDbLog subdirectory, but not the failarch subdirectory, by using the RECOVERYDIR parameter on the DSMSERV RESTORE DB command. Consider allocating a relatively large amount of temporary disk space for the restore operation. Because database restore operations occur relatively infrequently, the RstDbLog subdirectory can contain many logs from backup volumes that are stored in preparation for pending rollforward-restore processing.

 Also Read: How to increase or decrease TSM DB, active log and archive log size ?

If you are using ARCHFAILOVERLOGDIRECTORY server option

If you specify the ARCHFAILOVERLOGDIRECTORY server option or the ARCHFAILOVERLOGDIRECTORY parameter in the DSMSERV FORMAT or DSMSERV LOADFORMAT command, the server creates the RstDbLog and failarch subdirectories in the archive failover-log directory. 
dsmserv format dbdir=/tsmdb001 activelogdirectory=/home/tsminst1/inst1/activelog archlogdirectory=/home/tsminst1/inst1/archlog  archfailoverlogdirectory=/home/tsminst1/inst1/archlogfailover

The server also updates the DB2® parameter OVERFLOWLOGPATH that points to the RstDbLog subdirectory and the DB2 parameter FAILARCHPATH, that points to the failarch subdirectory. For example, suppose that you specify archlogfailover as the value of the ARCHFAILOVERLOGDIRECTORY parameter on the DSMSERV FORMAT command:

If you are using ARCHLOGDIRECTORY server option 

If you do not set the ARCHFAILOVERLOGDIRECTORY parameter  or server option, the server automatically creates the subdirectories RstDbLog and failarch in
the directory that is specified for the ARCHLOGDIRECTORY parameter.  In addition, the server updates the DB2 parameters OVERFLOWLOGPATH and FAILARCHPATH to
point to those subdirectories.


For example, suppose that you specify a value of archlog for the ARCHLOGDIRECTORY parameter in a DSMSERV FORMAT command. You do not specify the ARCHFAILOVERLOGDIRECTORY parameter:
dsmserv format dbdir=/tsmdb001 activelogdirectory=/home/tsminst1/inst1/activelog archlogdirectory=/home/tsminst1/inst1/archlog 

If you are using the RECOVERYDIR server option

For a database restore operation, you can specify a temporary location for the RstDbLog subdirectory by using the RECOVERYDIR parameter on the DSMSERV RESTORE DB command. The Tivoli Storage Manager server creates the RstDbLog subdirectory in the directory that is specified by that parameter. The server does not create the failarch subdirectory. The server also updates the DB2 parameter, OVERFLOWLOGPATH, that points to RstDbLog. 

 Also Read: Taking TSM server DB backup when the server is down

Restriction: The location specified by the RECOVERYDIR parameter takes precedence over the location specified by the ARCHFAILOVERLOGDIRECTORY or ARCHLOGDIRECTORY server option or parameter.

For example, for a point-in-time database restore, you can issue the following command:
dsmserv restore db todate=5/12/2011 totime=14:45 recoverydir=/home/tsminst1/inst1/recovery 

Follow these steps to change the TSM DB and Recovery Log filesystems

23:36 No Comments
You can move or change the TSM DB, Active log, Archive Log and Archive failover logs to the new directories or new filesystems if required. Follow the below steps to achieve this goal. However, it is highly recommend to take FULL DB backup before doing these below steps. Also make sure to make a copy of Volhist.out and dsmserv.opt files in safe location just incase if you need to restore the TSM DB.

Moving only TSM database to the new directory

To move the database from one location on the server to another location, follow this procedure
  • Back up the database by issuing the following command: 
backup db type=full devclass=LTO
  • Halt the server.
  • Create directories for the database. The directories must be accessible to the user ID of the database manager. For example:
mkdir /tsmdb005

mkdir /tsmdb006
mkdir /tsmdb007
mkdir /tsmdb008
  • Create a file that lists the locations of the database directories. This file will be used if the database must be restored. Enter each location on a separate line. For example, here are the contents of the dbdirs.txt file:

/tsmdb005
/tsmdb006
/tsmdb007
/tsmdb008
  • Remove the database instance by issuing the following command:

dsmserv removedb TSMDB1
  • Issue the DSMSERV RESTORE DB utility to move the database to the new directories. For example:

dsmserv restore db todate=today on=dbdir.file
  • Start the server.
Also Read: How to increase or decrease TSM DB, active log and archive log size ?

Moving only TSM Active log to the new directory

You can move only the active log from one directory to another by following these steps
  • First, Halt the server.
  • Create a new active log directory by issuing the following command:

mkdir /activelog2
  • Update the dsmserv.opt option file for the new active log directory by issuing the following command:

activelogdirectory /activelog2
  • Restart the server. The active logs are automatically moved by the database manager from the old directory to the new directory.
  • Now you can delete the old directory.
Also Read: Taking TSM server DB backup when the server is down

Moving only TSM Archive log to the new directory

You can also move only the TSM archive log from one directory to another. Follow these steps to do this
  • First, Halt the server.
  • Create an archive log directory by issuing the following command:

mkdir /archivelog2
  • Update the dsmserv.opt option file for the new archive log directory by issuing the following command:

archlogdirectory /archivelog2
  • Restart the server.
  • Move the archive logs from the old directory to the new directory. Preserve any subdirectory structure. Use and verify a recursive copy directory command. For example:

cp -r /archivelog/*   /archivelog2
  • Now you can remove the old directory.
Also Read: Steps to do after successful TSM DB restore

Moving only the TSM Archive failover log to the new directory

Move only the archive failover log from one directory to another by following these steps
  • Halt the server.
  • Create an archive failover log directory by issuing the following command:

mkdir /tsmserver1/archfaillog2
  • Update the dsmserv.opt option file for the new archive failover log directory by issuing the following command:

archfailoverlogdirectory /tsmserver1/archfaillog2
  • Restart the server.
  • Copy or move the archive log from the old directory to the new directory. Preserve any subdirectory structure. Use and verify a recursive copy directory command. For example:
cp -r /tsmserver1/archfaillog/*   /tsmserver1/archfaillog2

  • Now you can remove the old directory.

Use dsmserv utility to change TSM DB and log directories

23:33 No Comments
You can move or change the TSM database, active log, and archive logs that are on the same file system to various directories on different file systems if you require. Follow the below steps to change the TSM Database and Log directories. This process involves risk and need to planned properly before implementing. Always take full TSM DB backup before making any changes
  • Back up the database by issuing the following command:
backup db type=full devclass=files
  • Halt the server.
  • Create directories for the database, active logs, and archive logs. The directories must be accessible to the user ID of the database manager. For example in UNIX:


mkdir /tsmdb005



mkdir /activelog2



mkdir /archivelog2




In Windows



mkdir l:\tsm\db005



mkdir p:\tsm\activelog





    

  • Create a file that lists the locations of the database
directories. This file will be used if the database must be restored.
Enter each location on a separate line. For example, here
are the contents of the dbdirs.txt file.
    • 





/tsmdb005
/tsmdb006
/tsmdb007
/tsmdb008










On Windows








l:\tsm\db005
m:\tsm\db006
n:\tsm\db007
o:\tsm\db008


    

  • Remove the database instance by issuing
the following command:
    • 





dsmserv removedb TSMDB1


    

  • Issue the DSMSERV RESTORE DB utility
to move the database and create the new active log. For example:
    • 





dsmserv restore db todate=today on=dbdirs.txt activelogdirectory=/activelog2







On Windows










dsmserv restore db todate=today on=dbdirs.txt activelogdirectory=p:\tsm\activelog 


    

  • Restart the server.
    • 





    

  • Now, move the archive logs from the old directory to the new
directory. Ensure that you preserve any subdirectory structure. Use
and verify a recursive copy directory command:
    • 










cp -r /archivelog/* /archivelog2


 


 


xcopy /s k:\tsm\archivelog\*   q:\tsm\archivelog 


    





















        

      











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