http://microstare.com/Interview_Answers/vmax.htm write folding and continuous checkpoints SRDF/Asynchronous ongoing process of starting and stopping Capture Delta Sets and promoting them to Transmit Delta Sets SMC 1) Allows customers to manage multiple EMC Symmetrix V-Max Systems 2) The SMC gives the customer capabilities for Discovery, Configuration, Monitoring, Administration and Replication Management. 3) The Symmetrix Management Console 7.0 only works with Symmetrix V-Max systems 4) The Symmetrix Management Console is installed on the Service Processor of the V-Max System and can also be installed on a host in the SAN environment. can do trending, performance reporting, planning and consolidation using SMC SMC will help customers reduce their TCO with V-Max Systems 7) It takes minutes to install. Windows environment running a Windows Server 2003 along with IIS would be the best choice. 8 ) The interface the customers work on is a GUI. It has the looks and feels of ECC and the Console also integrates with ECC. 9) New Symmetrix V-Max systems are configured and managed through the Symmetrix Management Console. 11) Alert Management SMC now becomes a licensed product, which the customers will have to pay for 13) allows to perform configuration changes like creating and mapping masking devices, changing device attributes, flag settings, etc 14) Perform replication functions using SMC like Clone, Snap, Open Replicator, etc 15) SMC enables Virtual Provisioning with the Symmetrix V-Max arrays 16) Enables Virtual LUN technology for automated policies and tiering. 17) Auto Provisioning Group technology is offered through wizards in SMC 18) Dynamic Cache Partitioning: Allocates and deallocates cache based on policies and utilization. 19) Symmetrix Priority Controls RVA is available from Vmax starting enginuity 5784. The optimizer swap process now uses the RAID Virtual Architecture for swap operations Core Software Bundled Software Optional Software Open Replicator for Symmetrix – Heterogeneous, open-systems array-based migration SRDF/DM – High performance Symmetrix to Symmetrix migration Open Migrator – Host-based open systems data migration Federated Live Migration (FLM) – FLM using Open Replicator non-disruptively migrates workloads and redirects/hosts to the VMAX Write pending STP ======================================= How you integrate SNMP to Storage to receive alert messages? What are the parameters configured for VMAX monitoring? Array Component Events Hotspare Invoked Array Events Migration Complete Alert CG Tripped Optimizer switched mode DB Checksum Triggered Port Link Status Deferred Service Threshold Alert Port Status Device Config Change RVA Spare Coverage Device Pool Config Change SP Alerts Device Pool Status SRDF Alerts Device Status SRDF Link Status Director Status SRDF/A No Cycle Switch Alert Disk Status SRDF/A Session Environmental Alert SRDF/A session dropped, transit idle state timeout Event Lost Alert SRDF/A Session entering transmit idle state Event Overflow Alert SRDF/A Session recovered from a transmit idle state FAST Controller switched state Thin Device Allocation FAST FTS Performance Thin Device Usage GK Timeout Thin Pool Rebalancing Complete Alert GK Utilization User approval required for Optimizer/FAST Config Chan storapid – Base Daemon storgnsd – GNS Daemon storrdfd – RDF Daemon storevntd – Event Daemon storstpd – STP Daemon storwatchd – Watchdog Daemon, UNIX only storsrvd – SYMAPI Server Daemon The maximum number of storage group allowed per array is 8192. Each storage group can contain up to 4096 devices. Each Symmetrix device can belong to more than one storage group. =================== ESRS? What is the FAN-OUT ration of VMAX? - 512 How many Initiators can be masked to one FA Port in VMAX? 256 Differences between 5874 and 5875 FAST VP (Virtual Pools) – SUB LUN Tiering DARE (RSA based Encryption technology) added natively VSI (Virtual Storage Integrator) Addition of 10GB SRDF and iSCSI Directors FLM (Federated Live Migration) VAAI Support ZPR or Zero Page Reclaim Maximum number of IOPS on VMAX -- 10000 with 240 and 20000 with 480 Hot spare types Two spare drives for every 100 physicals of each drive type, or portion thereof Minimum of eight spare drives for the entire system Dynamic Cache partitioning http://lejyphilip.blogspot.sg/2012/06/normal-0-false-false-false.html http://www.emcsaninfo.com/2012/11/emc-vmax-architecture-detailed-explanation.html http://www.brainshark.com/emcworld/vu?pi=zGbz18nCG7zB8sLz0 Maximum number of tiers in Fast VP - 3 Local + one external device pool Size of the chunk moved in fast VP - 768KB Time period setting for FAST VP - minimum 24 hours Types of Locks in VMAX? Internal and external external are from 0 to 15 from SYMAPI and > 15 are emc application locks Internal are specific to the device locks how to discover the symmetrix in EMC Control ceter Port Flags Windows Server 2003 Common Serial Number (C) Enable Auto Negotiation (EAN) Enable Point-to-point (PP) Host SCSI Compliance 2007 (OS2007) SCSI-3 SPC-2 Compliance (SPC-2) Unique World Wide Name (UWN) SCSI-3 compliance (SC3) Windows Server 2003 with failover clustering Common Serial Number (C) Enable Auto Negotiation (EAN) Enable Point-to-point (PP) Host SCSI Compliance 2007 (OS2007) SCSI-3 SPC-2 Compliance (SPC-2) Unique World Wide Name (UWN) SCSI-3 compliance (SC3) ESX Common serial number (C) Auto negotiation (EAN) enabled Fibrepath enabled on this port (VCM) SCSI 3 (SC3) (Optional) Linux Unisphere supported from 5876 flag setting for windows, linux and ESX server? Total SRDF Groups supported 250 64 Groups on Single Port for SRDF IOPS per PORT of V-Max Systems 128 MB/s Hits 385 Read 385 Write IOPS for 2 PORT of V-Max Systems 128MB/s Hits 635 Read 640 Write how to setup DCP – data collection policies STP? Performance issue in VMAX Read SRDF Types of migration Read Hit Read Miss Fast Write Delayed Fast Write http://web.emc.com/vmax http://blog.nigelpoulton.com/vmax-comes-of-age/ Switch Log collection Cisco - show techsupport Brocade - support show & support save List some of the key intelligences of the Fibre Channel network? What is VSAN and how to create it? What is FCID? A switch assigns the FCID to each attached node, which is derived from the Domain_ID, Area_ID and WWN of the attached node. What is FLogi and pLOgi? how authentication happen? N_Port requests a unique 24-bit address from the Switch. The Fabric Login Server assigns the FCID to node, which is derived from the Domain_ID, Area_ID and WWN of the attached node. PLOGI N_Port informs the Fabric Name Server of its personality and capabilities. For example: WWNN, WWPN Buffer credits for flow control clock frequency ('speed capability') Upper layer protocol support (eg. SCSI-3, IP) PRLI Upper layer protocol communication. Well, ever since SCSI was designed and engineered (1970s, or so, previously SASI...), SCSI initiators need to discover SCSI targets. So, during PRLI, N_Port SCSI initiators discover N_Port SCSI targets (which is an opportunity for the host (maybe a UNIX host) to assign a target ID to the device path). Depending on the OS, you may be able to investigate further with commands like: egrep -i 'flogi|plogi|prli' /var/adm/messages What are buffer credits? Buffer-to-buffer credits (BB_credits) are a flow-control mechanism to ensure that Fibre Channel switches do not run out of buffers, so that switches do not drop frames. BB_credits are negotiated on a per-hop basis. For 16-port switching modules and full rate ports, the default value is 16 for Fx mode and 255 for E or TE modes. The maximum value is 255 in all modes. This value can be changed as required. For 32-port switching modules and host-optimized ports, the default value is 12 for Fx, E, and TE modes. These values cannot be changed. http://www.emcsaninfo.com/2013/02/useful-cisco-san-switch-clis-commandszoning-using-cisco-cli.html Monitoring of CISCO switches 1. what is name server ? 2. port types ? 3. Fabric Login Process 4. ISL ( Inter switch link) – how to ? 5. Fabric limitations 6. VSAN in Cisco 7. what is the status of the empty port ? 8. process to change the faulty switch? 9. what is Fabric? 10. types of fabric switch management? 11. configuring the switch? http://www.computerweekly.com/podcast/SAN-switching-How-to-configure-a-SAN-switch http://www.sanfoundry.com/fc-hardware-questions-answers/ Classes of service are available in Fibre Channel Class-1: Dedicated connection between two communicators with acknowledgement of frame delivery. In class 1 service, a dedicated connection source and destination is established through the fabric for the duration of the transmission. It provides acknowledged service. This class of service ensures that the frames are received by the destination device in the same order in which they are sent, and reserves full bandwidth for the connection between the two devices. It does not provide for a good utilization of the available bandwidth, since it is blocking another possible contender for the same device. Because of this blocking and necessary dedicated connection, class 1 is rarely used. Class-2: connection less but provides acknowledgement Class 2 is a connectionless, acknowledged service. Class 2 makes better use of available bandwidth since it allows the fabric to multiplex several messages on a frame-by-frame basis. As frames travel through the fabric they can take different routes, so class 2 service does not guarantee in-order delivery. Class 2 relies on upper layer protocols to take care of frame sequence. The use of acknowledgments reduces available bandwidth, which needs to be considered in large-scale busy networks. Class-3: connection less and provides no notification of delivery There is no dedicated connection in class 3 and the received frames are not acknowledged. Class 3 is also called datagram connectionless service. It optimizes the use of fabric resources, but it is now upper layer protocol to ensure that all frames are received in the proper order, and to request to the source device the retransmission of missing frames. Class 3 is a commonly used class of service in Fibre Channel networks. Class-4: allows fractional bandwidth for virtual circuits Class 4 is a connection-oriented service like class 1, but the main difference is that it allocates only a fraction of available bandwidth of path through the fabric that connects two N_Ports. Virtual Circuits (VCs) are established between two N_Ports with guaranteed Quality of Service (QoS), including bandwidth and latency. Like class 1, class 4 guarantees in-order delivery frame delivery and provides acknowledgment of delivered frames, but now the fabric is responsible for multiplexing frames of different VCs. Class 4 service is mainly intended for multimedia applications such as video and for applications that allocate an established bandwidth by department within the enterprise. Class 4 was added in the FC-PH-2 standard. Class -5: Class 5 is called isochronous service, and it is intended for applications that require immediate delivery of the data as it arrives, with no buffering. It is not clearly defined yet. It is not included in the FC-PH documents. Class-6: Provides multicast, dedicated connection with acknowledgment Class 6 is a variant of class 1, known as multicast class of service. It provides dedicated connections for a reliable multicast. An N_Port may request a class 6 connection for one or more destinations. A multicast server in the fabric will establish the connections and get acknowledgment from the destination ports, and send it back to the originator. Once a connection is established, it should be retained and guaranteed by the fabric until the initiator ends the connection. Class 6 was designed for applications like audio and video requiring multicast functionality. It appears in the FC-PH-3 standard. Class-F: used for switch to switch communication in the fabric. Class F service is defined in the FC-SW and FC-SW-2 standard for use by switches communicating through ISLs. It is a connectionless service with notification of non-delivery between E_Ports used for control, coordination, and configuration of the fabric. Class F is similar to class 2; the main difference is that Class 2 deals with N_Ports sending data frames, while Class F is used by E_ports for control and management of the fabric. a)Fabric Login b)SNS c)Fabric Address Notification d)Registered state change notification e)Broadcast Servers 51.What are the layers of Fibre Channel Protocol? a)FC Physical Media b)FC Encoder and Decoder c)FC Framing and Flow control d)FC Common Services e)FC Upper Level Protocol Mapping 57.How does FC Switch maintain the addresses? FC Switch uses simple name server (SNS) to maintain the mapping table What is the smallest unit of information transfer in FC? Frame 66.How is the capacity of the HDD calculated? Number of Heads X Number of Cylinders X Sectors per track X Sector Size 68.What are two types of recording techniques on the tapes? a)Linear Recording b)Helical Scan Recording. Types of login Port Login: To exchange service parameters between N_Ports and N_Ports Process Login: To establish the SCSI operating environment between two N_PORTS Fabric Login: Similar to port login, FLOGI is an extended link service command that sets up a session between two participants. With FLOGI a session is created between an N_Port or NL_Port and the switch. 90.What is BER/Bit error rate? Probability that a transmitted bit will be erroneously received is the measure of number of bits (erroneous) at the output of the receiver and dividing by the total number of bits in transmission. 93.What is burst Length? The burst length is the number of bytes that the SCSI initiator sends to the SCSI target in the FCP_DATA sequence. Pages to open http://www.emcsaninfo.com/2013/02/useful-brocade-san-switch-cli-commands.html http://www.emcsaninfo.com/2013/02/useful-cisco-san-switch-clis-commandszoning-using-cisco-cli.html http://nilamburbose.blogspot.sg/2012/06/emc-vmax-interview-questions.html http://www.aiotestking.com/emc/category/exam-e20-517-symmetrix-solutions-specialist-exam-for-storage-administrators-update-june-13th-2013/page/11/ http://class10e.com/emc/tag/exam-e20-517/page/11/ https://community.emc.com/docs/DOC-7195 Fabric &&&&&&&&&&&&&&&&&&& 57.How does FC Switch maintain the addresses? FC Switch uses simple name server (SNS) to maintain the mapping table What is the smallest unit of information transfer in FC? Frame 66.How is the capacity of the HDD calculated? Number of Heads X Number of Cylinders X Sectors per track X Sector Size 68.What are two types of recording techniques on the tapes? a)Linear Recording b)Helical Scan Recording. Types of login Port Login: To exchange service parameters between N_Ports and N_Ports Process Login: To establish the SCSI operating environment between two N_PORTS Fabric Login: Similar to port login, FLOGI is an extended link service command that sets up a session between two participants. With FLOGI a session is created between an N_Port or NL_Port and the switch. 90.What is BER/Bit error rate? Probability that a transmitted bit will be erroneously received is the measure of number of bits (erroneous) at the output of the receiver and dividing by the total number of bits in transmission. 93.What is burst Length? The burst length is the number of bytes that the SCSI initiator sends to the SCSI target in the FCP_DATA sequence. http://sanengineers.wordpress.com/srdfa-best-practices/ - DCX Symmetrix monitoring Switches - Cisco, DCX Unisphere for VMAX Symmetrix Performance monitoring pool balance varience zero space reclaim push or pull? SRDF from thick to thin and larger size R2 Each SRDF base solution operates in one of the following modes of operation: ? synchronous ? semi-synchronous ? adaptive copy ? asynchronous Synchronous and semi-synchronous modes are the primary modes of operation while adaptive copy modes are the secondary modes of operation asynchronous mode mirrors R1 devices by maintaining a dependent-write consistent copy of the data on the secondary (R2) site at all times. SRDF/A session data is transferred from the primary to the secondary site in cycles Semi-synchronous mode is supported with Enginuity versions prior to 5773. Semi-synchronous mode allows the R1 and R2 devices to be out of synchronization by one write I/O operation. Adaptive copy modes write pending and adaptive copy disk. Adaptive copy modes do not guarantee a dependent-write consistent copy of data on R2 devices. Number of tracks out of synchronization between the R1 and the R2 devices at any given time is determined by the maximum skew value SRDF/A will capture a delta set of writes and send them in cycles across the link. In addition to the new writes, SRDF/A will include up to 30,000 invalid tracks per cycle. This is a design feature and the 30,000 track value was chosen to prevent cache from being flooded by the invalid tracks Therefore, EMC generally recommends as a best practice to synchronize the boxes in Adaptive Copy Disk mode to below 30,000 invalid tracks before activating SRDF/A SRDF/A works in cycle of four steps ( recieve the data, gather the data for the till the predefined cycle time, send the data, and wait for acknowledgments). in SRDF/A writes are destaged to disk only after they have been copied over the RDF links. In a given point of time there are one one "cycle switc "which is send over the rdf link and waiting for the ACK and the SAME time another cycle is doing "recieve the data and gathering data " . So if a failure ocurs during this stage you lose maximum two "cycle switches of data" one being waiting for the ACK and the other one being the "receive/gather" state. That is how the "twice the cycle time" .. SRDF/A default cycle switch time is 30 second, and most recents code(5875) you can see the default is 15 seconds. symcfg list -rdfg all` symdev show on the R1 volume shows the R1 R2 time lag srdf A will give you RPO of 2cycles.. DR is always 2 cycles behind the production To understand how delta set pushes the data to R2, you can look at the SRDF product guide. In a nutshell, SRDF/A works in Cycle. 1) Capture 2) Transmit 3) Recieve 4) Apply Lets assume your minimum cycle time is 30 sec, so R1 symm will start capturing the data for 30 sec and then do a cycle switching (Capture cycle becomes transmit and tranmit becomes Capture). Once the data reaches to transmit, it starts sending it over the RDF link to R2 Symm where it is received in Receive cycle, again after 30 sec, cycle switching happens (receive cycle becomes apply and apply becomes receive) and whatever data in Apply cycle is destaged to the disk. SyncInProg A synchronization is currently in progress between the R1 and the R2. There are existing invalid tracks between the two pairs and the logical links between both sides of an SRDF pair are up. Synchronized The R1 and the R2 are currently in a synchronized state. The same content exists on the R2 as the R1. There are no invalid tracks between the two pairs. Split The R1 and the R2 are currently ready to their hosts, but the links are not ready or write disabled. Failed Over The R1 is currently not ready or write disabled and operations have been failed over to the R2. R1 Updated The R1 is currently not ready or write disabled to the host, there are no local invalid tracks on the R1 side, and the links are ready or write disabled. R1 UpdInProg The R1 is currently not ready or write disabled to the host, there are invalid local (R1) tracks on the source side, data is being copied from the R2 to the R1 device, and the links are ready. Suspended The SRDF links have been suspended and are not ready or write disabled. If the R1 is ready while the links are suspended, any I/O will accumulate as invalid tracks owed to the R2. Consistent The R2 SRDF/A capable devices are in a consistent state. Consistent state signifies the normal state of operation for device pairs operating in asynchronous mode. Transmit Idle The SRDF/A session cannot push data in the transmit cycle across the link because the link is down. Symmetrix array keeps an account of the tracks that are "owed" to the other side. The owed tracks are known as remote invalids http://richgoldstein.net/content/emc/srdf_intro --- Device states symrdf -rdf -sid 123 ping data from R1 to a larger R2 device You can copy data from an R1 device to a larger R2 device but the following restrictions apply: All swap and SRDF/Star operations are blocked. If SYMAPI_RDF_CREATEPAIR_LARGER_R2 is set to DISABLE in the options file, all createpair operations are blocked. Data mirrored to a larger R2 device cannot be restored back to its R1 device. Concatenated metadevices are not supported but striped metadevices are supported. Consistency exempt feature in Enginuity 5874 provides the ability to dynamically add and remove volumes from an active SRDF/A session without affecting the state of the SRDF/A session or the reporting of the SRDF pair state for each of the volumes in the active session that are not the target of the add or remove operation. This is achieved by marking the volumes being added or removed as “exempt” from being considered when calculating the consistency state of the volumes in the SRDF/A session or when deciding if the SRDF/A session should be dropped to maintain dependent write consistency on the R2 side. Setting the consistency exempt flag on a volume allows the volume to be added or removed from an active SRDF/A SRDF group using either a create, delete, or move operation without requiring the other volumes in the SRDF group to be suspended prior to the operation An R1 SRDF mirror indicates that data stored on the R1 device is also remotely mirrored to the R2 device. Likewise, an R2 SRDF mirror indicates that data stored on the R2 device is remotely mirrored to the R1 device Static Devices need to be converted to RDF before the pair created. Static requires Bin changes however dynamic can be changed online Enginuity version 5875, SRDF supports zero space reclamation. Zero space reclamation is an Enginuity feature that allows you to remotely mirror a thick SRDF device to a thin SRDF device while avoiding mirroring pre-allocated zero data chunks that may be associated with a thick SRDF device RAID 6 A RAID 6 group consists of 8 or 16 RAID members. Data and horizontal and diagonal parity blocks are distributed across all RAID members. RAID 6 protects data in the event of one or two drive failures. Fabric fan out ratio is number of host HBA connected to storage port. The standard is 10:1 and is defined by the Storage vendors Symmetrix director flags (bits) The following FA director flag settings need to be configured to support Windows Server 2003 and 2008 Common Serial Number (C) Host SCSI Compliance 2007 (OS2007) SCSI-3 SPC-2 Compliance (SPC2) SCSI-3 compliance (SC3) For FC Switch Base Topology (FC-SW), Enable Auto Negotiation (EAN), Point-to-Point (PP) , Unique WWN (UWN). Additionally for Windows 2008 Failover Cluster, the Persistent Reservation attribute SCSI3_persist_reserv must be enabled on each Symmetrix DMX device used. This should NOT be done to devices for Windows 2003 clusters. EMC recommends that the SCSI3_persist_reserv attribute be only set on devices that require it. To display what director flags have been set per host initiator, run the following Solutions Enabler command. symmaskdb -sid XXXX list database -v (without the -v you will not see the flags) To enable the necessary director flags for an initiator on director 4a port 0 using symmask: symmask -sid xxxx -wwn xxxxxxxxxxxxx -dir 4a -p 0 set hba_flags on C,OS2007,SC3,SPC2 -enable symmask refresh (this command is required after performing the above command) To enable the necessary director flags for an initiator group using Symaccess: symaccess -sid xxxx -type init -name myig1 set ig_flags on C,OS2007,SC3,SPC2 -enable To display the flags from the previous command using symmaccess: symaccess -sid xxxx -type init show myig1 -detail To enable the SC3, SPC2 & OS2007 flags globally on the FA 1D port 0 via symconfigure, create a text file similar to below.. set port 1d:0 SCSI_3=enable, SPC2_Protocol_Version=enable, SCSI_Support1=enable; the SC-3, SPC-2, and OS2007 Edit Director flags can be enabled with the Symmetrix online. These flags can be enabled via a EMC CE applied bin file change. The flags may be changed one port at a time via multiple bin file changes or they may all be enabled simultaneously in one bin file change. This will invoke the online Change_Director_Flags (CdfOnl) script on the Symmetrix Service Processor. The SymmWin Change_Director_Flags (CdfOnl) script will not set the affected ports offline when changing these flags. However if enabling the SPC-2 Edit Director flag in the bin file via an ECC or Solutions Enabler configuration change (symconfigure set port command) then the EMC software will require that the affected FA ports be set offline before the activity can be performed In all cases, the changed state of these Edit Director flags will not be detected until the host HBA is logged out and logs back into the Symmetrix fibre channel (FA) Can these flags be changed with the hosts online? Yes, however a host reboot is required. For example (Symmetrix V-Max at 587x with with VMware 3.5, VMware ESX 4.0): Common serial number (C) Auto negotiation (EAN) enabled Fibrepath enabled on this port (ACLX) SCSI 3 (SC3) (Optional) OS2007 is optional (it can be enabled if required by other hosts in a port sharing heterogeneous host environment) 16GB FA port ============ Need Enginuity 5876 Q3 2013 SR Supported only Fibre channel(No Ethernet and iSCSI) Two ports per module Unisphere 1.6.1/Solutions Enabler 7.6 Supported for 10K(987) and 40K SFP+ (enhanced SFP) is required OM4 cables can be installed in 3,4,5 and 6 engines only. maximum 2 ports per module, 4 ports per director, 8 ports per engine and 32 ports per VMAX Supports 8/4Gbps. 2Gbps is not supported The port operates 8/4Gbps in arbitrated loop FTS/FLM in OR is not supported with this module This port cannot be used to convert as SRDF port Check these things ================= Traditional Licensing New style EMCLM licenses Host licensing Sym licensing EMCs2tepwd SMC Menu - Performance Analyzer - Trend/Snapshot