Can you explain about DMX Architecture?
The Symmetrix DMX features a high-performance, Direct Matrix
Architecture (DMX) supporting up to 128 point-to-point serial connections.
Symmetrix DMX technology is distributed across all channel directors, disk directors,
and global memory directors in symmetrix DMX systems.
Can you briefly explain about symmetrix series products?
Symmetrix 8000/4 was the first symmetrix to introduce a dual
bus arcitecture, providing redundancy in the path to memory.
Symmetrix DMX800 is an incrementally scalable, high-end storage array which features modular disk array enclosures.
Symmetrix Direct Matrix Architecture is storage array technology that employs a matrix of dedicated serial point-to-point connections instead of traditional buses or switches.
Symmetrix DMX2 is a channel director specification for the DMX with faster processors and newer components.
Symmetrix DMX-3 and DMX-4 are the latest technology using redundant global memory and largest capacity.
Symmetrix DMX800 is an incrementally scalable, high-end storage array which features modular disk array enclosures.
Symmetrix Direct Matrix Architecture is storage array technology that employs a matrix of dedicated serial point-to-point connections instead of traditional buses or switches.
Symmetrix DMX2 is a channel director specification for the DMX with faster processors and newer components.
Symmetrix DMX-3 and DMX-4 are the latest technology using redundant global memory and largest capacity.
Can you explain Enginuity release code 5773.79.58?
57 represents the DMX3/4 Hardware
73 represents the microcode family
79 represents the field release level to the microcode
58 represents the field release to the service processor code
52 =Symm4, 55 =Symm5, 56 =DMX/DMX2, 57 =DMX3/4, 58 =VMAX.
73 represents the microcode family
79 represents the field release level to the microcode
58 represents the field release to the service processor code
52 =Symm4, 55 =Symm5, 56 =DMX/DMX2, 57 =DMX3/4, 58 =VMAX.
How many Cache directors, Front-end directors and
Back-end directors we can use in DMX-4?
Cache Directors = 4 Min to 8 Max.
Front-end Directors = up to 12 max.
Back-end Directors = 6 Min to 8 Max.
Front-end Directors = up to 12 max.
Back-end Directors = 6 Min to 8 Max.
What are the different types of Front-end directors and
the purpose of each one?
ESCON (EA) : for mainframe attachment and SRDF family links
FICON (EF) : provides the industry’s highest performance connectivity Option for the mainframe.
Fibre (FA/DA) : Connectivity option for open systems direct and SAN Attachment, and can be used for SRDF family remote Replication links.
iSCSI (SE) : Provides the industry’s first high-end Iscsi Implementation.
GigE (RE) : for SRDF family replication with compression support.
FICON (EF) : provides the industry’s highest performance connectivity Option for the mainframe.
Fibre (FA/DA) : Connectivity option for open systems direct and SAN Attachment, and can be used for SRDF family remote Replication links.
iSCSI (SE) : Provides the industry’s first high-end Iscsi Implementation.
GigE (RE) : for SRDF family replication with compression support.
Explain Rule 17 in DMX?
Possible answers:
Rule of 17 ensured that FAs being used for host connectivity were in different power zones.
The rule of 17 is simply a way to make sure that the paths you connect your host to are not running on the same director, but one physically far away from it.
The original Rule of 17 was put into place to ensure that there was a path on each bus (odd and even).The bus architecture went away in DMX-1 ( Symm6). But we had 2 power zones; one zone for directors 1-8, and another zone for directors 9-16. So the Rule of 17 still had value.
but DIR 3 (odd) and DIR 4 (even) reside on different buses yet in the same power zone, so even if you had your host connected to 3 and 4 ..if that power zone went down ..Your hosts went down.
Rule of 17 ensured that FAs being used for host connectivity were in different power zones.
The rule of 17 is simply a way to make sure that the paths you connect your host to are not running on the same director, but one physically far away from it.
The original Rule of 17 was put into place to ensure that there was a path on each bus (odd and even).The bus architecture went away in DMX-1 ( Symm6). But we had 2 power zones; one zone for directors 1-8, and another zone for directors 9-16. So the Rule of 17 still had value.
but DIR 3 (odd) and DIR 4 (even) reside on different buses yet in the same power zone, so even if you had your host connected to 3 and 4 ..if that power zone went down ..Your hosts went down.
What are the Management Tools for DMX?
Symcli (Symmetrix Command Line Interface)
SMC (Symmetrix Management Console)
ECC (EMC Control Center)
SMC (Symmetrix Management Console)
ECC (EMC Control Center)
What are the Enginuity Operational Layes?
Symmetrix Based Application
Host Based Symmetrix Application
Independent Software vendor application
EMC Solutions Enabler API
Symmetrix Enginuity Operating Environment Functions
Symmetrix Hardware
Host Based Symmetrix Application
Independent Software vendor application
EMC Solutions Enabler API
Symmetrix Enginuity Operating Environment Functions
Symmetrix Hardware
What are the major components of System Bay and Storage
Bay in DMX?
System Bay Components:
Either six or eight disk directors and up to 12 channel directors (Combined total = 16).
From four to eight global memory directors.
Up to eight power supplies, each of having a dedicated Battery Back Up(BBU)
1U service processor with KVM (keyboard, video screen and mouse) and dedicated UPS.
Three cooling fan assemblies (each containing 3 fans).
Storage Bay Components:
120 or 240 disk drives per storage bay
Each Drive Enclosure (DE) includes:
Two link control cards (LCC).
Redundant power supplies with BBUs to provide standby power.
The DMX-4 storage bay has 2N power zones with independent power cables, each zone capable of powering the fully configured storage bay.
The storage bay can be populated with various combinations of currently available DMX one-inch low-profile 4 Gb/s Fibre Channel disk drives available in:
73 GB, 146 GB, 300 GB, and 400 GB Fibre Channel drives
73 GB and 146 GB Flash drives
500 GB and 1 TB SATA II disk drives
Either six or eight disk directors and up to 12 channel directors (Combined total = 16).
From four to eight global memory directors.
Up to eight power supplies, each of having a dedicated Battery Back Up(BBU)
1U service processor with KVM (keyboard, video screen and mouse) and dedicated UPS.
Three cooling fan assemblies (each containing 3 fans).
Storage Bay Components:
120 or 240 disk drives per storage bay
Each Drive Enclosure (DE) includes:
Two link control cards (LCC).
Redundant power supplies with BBUs to provide standby power.
The DMX-4 storage bay has 2N power zones with independent power cables, each zone capable of powering the fully configured storage bay.
The storage bay can be populated with various combinations of currently available DMX one-inch low-profile 4 Gb/s Fibre Channel disk drives available in:
73 GB, 146 GB, 300 GB, and 400 GB Fibre Channel drives
73 GB and 146 GB Flash drives
500 GB and 1 TB SATA II disk drives
Can you explain about Read Hit, Read Miss and Fast Write
and Delayed Write?
Read Hit: In a read hit operation, the requested data
resides in global memory. The channel director transfers the requested data
through the channel interface to the host and updates the global memory
directory. Since the data is in global memory, there are no mechanical delays
due to seek and latency.
Read Miss: In a read miss operation, the requested data is not in global memory and must be retrieved from a disk device. While the channel director creates space in the global memory, the disk director reads the data from the disk device. The disk director stores the data in global memory and updates the directory table. The channel director then reconnects with the host and transfers the data. because the data is not in global memory, the symmetrix system must search for data on the disk and then transfer it to the channel adding seek and latency times to the operation.
Fast Write A fast write occurs when the percentage of modified data in global memory is less than the fast write threshold. On a host write command, the channel director places the incoming blocks directly into global memory. For fast write operations, the channel director stores the data in global memory and sends a “channel end” and “device end” to the host computer. The disk director then asynchronously destages the data from global memory to the disk device.
Delayed Fast Write: A delayed fast write occurs only when the fast write threshold has been exceeded. That is the percentage of global memory containing modified data is higher than the fast write threshold. If this situation occurs, the symmetrix system disconnects the channel directors from the channels. The disk director then de-stages the data to disk. When sufficient global memory space is available. The channel directors reconnect to their channels and process the fast I/O requires as a fast write. The symmectrix system continues to process read operations during delayed fast writes with sufficient global memory present, this type of global memory operation rarely occurs.
Read Miss: In a read miss operation, the requested data is not in global memory and must be retrieved from a disk device. While the channel director creates space in the global memory, the disk director reads the data from the disk device. The disk director stores the data in global memory and updates the directory table. The channel director then reconnects with the host and transfers the data. because the data is not in global memory, the symmetrix system must search for data on the disk and then transfer it to the channel adding seek and latency times to the operation.
Fast Write A fast write occurs when the percentage of modified data in global memory is less than the fast write threshold. On a host write command, the channel director places the incoming blocks directly into global memory. For fast write operations, the channel director stores the data in global memory and sends a “channel end” and “device end” to the host computer. The disk director then asynchronously destages the data from global memory to the disk device.
Delayed Fast Write: A delayed fast write occurs only when the fast write threshold has been exceeded. That is the percentage of global memory containing modified data is higher than the fast write threshold. If this situation occurs, the symmetrix system disconnects the channel directors from the channels. The disk director then de-stages the data to disk. When sufficient global memory space is available. The channel directors reconnect to their channels and process the fast I/O requires as a fast write. The symmectrix system continues to process read operations during delayed fast writes with sufficient global memory present, this type of global memory operation rarely occurs.
How do you calculate number of cylinders for 120 GB LUN?
Maximum device sizes by Enginuity version
Enginuity version:__________:MBs:_______:CYLs:______:GBs
Enginuity 5874:_____________:245760:____:262668:____:240
Enginuity 5773 and earlier:_:61425:_____:65520:_____:59
Since DMX-4 supports maximum of 60GB hyper size, we have to create two hypers and form a Meta devices as 120GB LUN.
To calculate cylinders for 60GB LUN use the below formula
Cylinders = 60GB/15 tracks* 8 sectors* 16 blocks * 512 bytes
Cylinders = 60000000000/15*8*16*512
Cylinders = 60000000000/983040
Cylinders = 61035 cyl
To calculate the number of cylinders (for pre-Symmetrix DMX), use either of the following: blocks ÷ 960 or (size in megabytes) x 2.1333
To calculate the number of cylinders (for Symmetrix DMX and Symmetrix V-Max arrays), use the following: 1 cylinder = 15 tracks; each track is 64 KB, 15 x 64 tracks = .937 MB for each cylinder
Enginuity version:__________:MBs:_______:CYLs:______:GBs
Enginuity 5874:_____________:245760:____:262668:____:240
Enginuity 5773 and earlier:_:61425:_____:65520:_____:59
Since DMX-4 supports maximum of 60GB hyper size, we have to create two hypers and form a Meta devices as 120GB LUN.
To calculate cylinders for 60GB LUN use the below formula
Cylinders = 60GB/15 tracks* 8 sectors* 16 blocks * 512 bytes
Cylinders = 60000000000/15*8*16*512
Cylinders = 60000000000/983040
Cylinders = 61035 cyl
To calculate the number of cylinders (for pre-Symmetrix DMX), use either of the following: blocks ÷ 960 or (size in megabytes) x 2.1333
To calculate the number of cylinders (for Symmetrix DMX and Symmetrix V-Max arrays), use the following: 1 cylinder = 15 tracks; each track is 64 KB, 15 x 64 tracks = .937 MB for each cylinder
This is dummy text. It is not meant to be read. Accordingly, it is difficult to figure out when to end it. But then, this is dummy text. It is not meant to be read. Period.