LUN (Logical Unit Number) Masking is an authorization process that makes a LUN available to some hosts and unavailable to other hosts.
LUN Masking is implemented primarily at the HBA (Host Bus Adapter) level. LUN Masking implemented at this level is vulnerable to any attack that compromises the HBA. Some storage controllers also support LUN Masking.
LUN Masking is important because Windows based servers attempt to write volume labels to all available LUN’s. This can render the LUN’s unusable by other operating systems and can result in data loss.
Device masking lets you control your host HBA access to certain storage arrays devices. A device masking database, based in the storage arrays unit, eliminates conflicts through centralized monitoring and access records. Both HBA and storage arrays director ports in their Channel topology are uniquely identified by a 64-bit World Wide Name (WWN). For ease of use, you can associate an ASCII World Wide Name (AWWN) with each WWN.
How Will You Ensure That San-attached Tape Devices Are Represented Consistently In A Host Operating System?
Logical Unit Number or LUN is a logical reference to entire physical disk, or a subset of a larger physical disk or disk volume or portion of a storage subsystem.
WWN zoning uses name servers in the switches to either allow or block access to particular World Wide Names (WWNs) in the fabric. A major advantage of WWN zoning is the ability to recable the fabric without having to redo the zone information. WWN zoning is susceptible to unauthorized access, as the zone can be bypassed if an attacker is able to spoof the World Wide Name of an authorized HBA.
Port sectionalisation utilizes physical ports to outline security zones. A user’s access to knowledge is decided by what physical port he or she is connected to. With port sectionalisation, zone info should be updated whenever a user changes switch ports. additionally, port sectionalisation doesn’t enable zones to overlap. Port sectionalisation is generally enforced victimization onerous sectionalisation, however might even be enforced victimization soft sectionalisation.
Soft sectionalisation uses filtering enforced in fibre channel switches to forestall ports from being seen from outside of their assigned zones. the protection vulnerability in soft sectionalisation is that the ports are still accessible if the user in another zone properly guesses the fibre channel address.
Display or list device masking objects and their relationships: Typical objects ar hosts, HBAs, s storage arrays devices, and Fibre Channel Adapter (FA) ports.
Modify properties, like names and access privileges related to device masking objects (for example, modification the Name of a host).
If the space is a smaller amount than some of miles, i will be able to use multimode fibre cable.
If the space is quite 3-5 miles, i will be able to use single mode fibre cable.
The needed Bandwidth=the required information measure is decided by mensuration the common range of write operations and therefore the average size of write operations over a amount of your time.
GUID Partition Table, GPT may be a a part of the EFI normal that defines the layout of the partition table on a tough drive. GPT provides redundancy by writing the GPT header and partition table at the start of the disk and additionally at the tip of the disk.
GPT Uses 64-bit LBA for storing Sector numbers. GPT disk will in theory support up to 2^64 LBAs. assumptive 512 computer memory unit sector emulation, most capability of a GPT disk = nine.4 x 10^21 bytes = nine.4 zettabytes (ZB)
A storage array uses spares disk drives to require the place of any disk drives that ar blocked as a result of errors. Hot spares are accessible and can spare out predictively once a drive fails.
Dynamic Sparing: knowledge from the unsuccessful or blocked drive is derived on to the new spare drive from the failing drive
Correction Copy: knowledge is regenerated from the remaining sensible drives within the parity cluster. For RAID 6, RAID 5, and RAID 1, when a unsuccessful disk has been replaced, the info is derived back to its original location, and therefore the spare disk is then accessible.
- What do you mean by EMC? …
- What is LUN Masking and why we need it? …
- Explain briefly about the EMC environment? …
- What is the LUN or logical unit number? …
- How will you calculate Max IOPS an HBA port can generate to buy any LUN? …
- What is Wmn Zoning? …
- What is the difference between Hard and soft zoning?
Frequently Asked EMC Interview Questions
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EMC Interview Questions And Answers
I will use the formula:
Total Approximate Drives required = (RAID Group IOPS / (Hard Drive Type IOPS)) + Large Random I/O adjustment + Hot Spares + System Drives
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These EMC Interview Questions have been designed specially to get you acquainted with the nature of questions you may encounter during your interview for the subject of EMC. As per my experience good interviewers hardly plan to ask any particular question during your interview, normally questions start with some basic concept of the subject and later they continue based on further discussion and what you answer.we are going to cover top EMC Interview questions along with their detailed answers. We will be covering EMC scenario based interview questions, EMC interview questions for freshers as well as EMC interview questions and answers for experienced.
1) Network FailSafe device is controlled by which switch protocol?
Ans: None
2) Which NetWorker feature enables multiple storage nodes to use the same device?
Ans: Dynamic drive sharing
3) What value has the address space been increased to with the introduction of IPv6?
Ans: 128 bits
4) What is the role of a NetWorker storage node?
Ans: Manages backup devices
5) Which protocol is used by open systems hosts to access storage in Fiber Channel SANs?
Ans: SCSI
6) A read cache miss operation on a Symmetrix has several steps. The first step is that the host sends a read request. What is the next step?
Ans: The Channel Director checks the track table.
7) What are two CLARiioN High Availability features?
Ans: Dual LCCs, Dual storage processor
8) What do VLANs reduce?
Ans: The number of packets processed by clients
9) What does EtherChannel link aggregation do?
Ans: Disables links of a different speed to the majority of links in the trunk
10) What is used by NetWorker to manage its configuration?
Ans: Resource directory
11) In Asynchronous transmissions how are characters transmitted?
Ans: Single characters are transmitted at a time
12) What is UDP?
Ans: Connectionless base protocol
13) What are VDMs?
Ans: VDMs are isolated CIFS servers with their own environments
14) What generates the Content Address for a Centera?
Ans: Hashing algorithm
15) Which level of backup is performed during a NetWorker consolidated backup?
Ans: 1
16) In a NetWorker browsable recovery, what is true about the destination client?
Ans: Must also be the administering client
17) In a NetWorker recovery, which client role performs the recovery?
Ans: Administering
18) What is Celerra Replicator?
Ans: Is an asynchronous data replication solution
19) What is the default subnet mask for an IPv4 Class B address?
Ans: 255.255.0.0
20) Which event occurs in a NetWorker server-initiated backup but NOT in a client-initiated backup?
Ans: Data life-cycle policies are enforced
21) How many octets in a default Class C IPv4 address make up the network portion?
Ans: 3
22) Which NetWorker resource is used to determine the backup level for a client?
Ans: Schedule
23) What is a characteristic of Centera?
Ans:Guaranteed content authenticity
24) What load balancing policies are available in PowerPath?
Ans: No Redirect, Round robin
25) Which of the following Symmetrix connectivity options can you use with Open Systems and Windows Hosts?
Ans:Fibre Channel and SCSI
26) Which of the following allows you to use ControlCenter Automated Resource Manager Storage Provisioning Services?
Ans: Storage pools and storage policies
27) In Celerra TimeFinder/FS Far Copy how does replication happen?
Ans: Source and Target are asynchronously replicated
28) In a Centera, what is a supported replication topology?
Ans: Star
29) How many optical network ports are available on a NS500 DataMover?
Ans: None
30) What does the OSI Physical layer provide?
Ans: The media specification
31) What is a function of the API for Centera?
Ans: Separates the BLOB from the metadata
32) What is true about FTP and TFTP ?
Ans: FTP uses port 21 and TFTP uses port 69
33) When is Celerra SRDF used?
Ans: Is implemented over a campus distance
34) How is free maintained in the CLARIION write cache?
Ans: Cache is flushed to the driver during I/O only the least -recently used page are flushed
35) Which symmetric presents devices to hosts?
Ans: Channel Director
LUN Masking is important because Windows based servers attempt to write volume labels to all available LUN’s. This can render the LUN’s unusable by other operating systems and can result in data loss. Device masking lets you control your host HBA access to certain storage arrays devices. A device masking database, based in the storage arrays unit, eliminates conflicts through centralized monitoring and access records. Both HBA and storage arrays director ports in their Channel topology are uniquely identified by a 64-bit World Wide Name (WWN). For ease of use, you can associate an ASCII World Wide Name (AWWN) with each WWN.
WWN zoning uses name servers in the switches to either allow or block access to particular World Wide Names (WWNs) in the fabric. A major advantage of WWN zoning is the ability to recable the fabric without having to redo the zone information. WWN zoning is susceptible to unauthorized access, as the zone can be bypassed if an attacker is able to spoof the World Wide Name of an authorized HBA.
Buffer credits, also called buffer-to-buffer credits (BBC) are used as a flow control method by Fibre Channel technology and represent the number of frames a port can store. Fibre Channel interfaces use buffer credits to ensure all packets are delivered to their destination. Flow-control mechanism to ensure that Fibre Channel switches do not run out of buffers, so that switches do not drop frames .overall performance can be boosted by optimizing the buffer-to-buffer credit allotted to each port.
Port zoning utilizes physical ports to define security zones. A user’s access to data is determined by what physical port he or she is connected to. With port zoning, zone information must be updated every time a user changes switch ports. In addition, port zoning does not allow zones to overlap. Port zoning is normally implemented using hard zoning, but could also be implemented using soft zoning.
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