To show the layout of what engines and dir where each different type of disks is located?

Ideally the each disk type should be evenly distributed across all directors/engines. You can see the disks behind each director with the "symdisk list" command.

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The ideal configuration will have equal numbers of each drive type on each DA director.

The most important drive type to have balanced are the EFDs, since they do the most IOPs per drive, and therefore the most IOPs on each DA CPU.

Hello emcmagic,

As sean said, balance all drives across all available DA's where possible. An ideal configuration would be multiple of 8 drives per engine-of the same type/speed (not including spares). This is important especially for EFDs, as Quincy mentioned.

The recommendation is to implement 8 EFDs per VMAX engine, or multiples of 8, across all VMAX engines (this does not includes spare EFDs). The use of the same sized EFDs within a single pool is critical to ensure even loading of EFDs and DA's. A balanced configuration of FC and SATA disks is recommended but is less critical, as each FC and SATA can only place a relatively small load on a DA, whereas a single EFD can place a significant load on the DA.

Say you have a 4 engine VMAX, which has 32 DA's but only 8 EFDs, with the 8 EFDs spread across just 1 engine as an example.

FAST VP will promote the most active extents from all of the FC and SATA disks to the 8 EFDs.The 8 EFDs in the 4 engine VMAX, which might represent less than 1% of the total useable capacity, will have a very good chance of being saturated with I/O and FAST VP will be busy promoting and demoting data. The DA's to which the 8 EFDs are configured will have a high utilization, while the remaining 24 DA's will have a low utilization, meaning that the response times will be impacted for the 8 EFDs and the FC and SATA disks attached to the same DA's as the EFDs.

Another point to note is that 2 x 200 GB EFDs are better than 1 x 400 GB EFD. The former will provide double the potential performance capability of one 400 GB EFD because both EFDs are able to support the same IOPS, so the 200 GB EFD is able to support double the I/O density, where I/O density is measured in IOPS/GB.

hope this helps.

thanks ..

The following A,B,C,D are representing directors in in each one of 4 engines, and 05-12 under SYMB are representing CPU's, and C and D under TID are representing ports, respectively. Then from this layout, it is in line with what you all just said that 32 EFD drives are evenly located under 4 engines and 8 drives each. However, my questions are following:

I'd like to correct you here ..

A,B,C,D are not directors. They are processors, and C and D are the ports on these processors that connect to your DAE's.

For example - 5A is a (back-end) director .. 5A:C is cabled to 1 DAE (the same DAE is connected to director 12A:C for backend redundancy) and 5A:C6 is your EFD within the DAE. [if you do a #symdisk list -da 5a -int c, you should be able to see all your drives on this DAE/loop, including the EFD at location 5A:C6]

1. why under director A, drives are spread under different CPU, whereas in the other cases, drives are under same CPU but different ports?

You should call it director 5A, or director 12D .. not director A.

From what I see, the drives are pretty much evenly distributed under the C and D ports for every back-end director.

Remember : just like you have ports 0 and 1 for your front-end director (5e:0, 5e:1, 5f:0, 5f:1, 5g..), you'd have ports C and D for your backend director.(5A:C, 5A:D, 5B:C, 5B:D, 5C: .. )

[port 0 and 1 on a slice (5e for example) share a CPU, similarly ports C and D on a slice(5A for example) share a CPU]

2. are there any reasons, drives are not put under some CPUs, for instance, 6B is missing?

your question should be : are there any reasons, drives (EFD's) are not put under some directors, for instance, 6B is missing?

3, why there are 9 drives under director B? I assume drive under 10A is spare drive, since Hypr is 0. If it is not, then why Hypr here is 0?

I see 9 drives under directors 7 and 8 (which will be contained in an engine). not sure on this.

Again, 10A is not a drive. 10A is a director and yes, 10A:D6 is a spare drive configured on the backend loop.

thanks.

HI All,

Following diagram shows how 8 DAE’s are directly connected to a VMAX engine:

Here is a sample list of drives in DAE 1:

Regards

Hi rohang,

I guess I still not fully understand the relationship of the engine and directory.

We have 32 EFD, and as you and others said, they should be evenly spread to 4 engines, so, each engine should have 8 EFD drives. Based on the output, is following correct?

DRIVES connecting on 05A-12A is located on engine,

DRIVES connecting 05B-11B on 2nd.

DRIVES connecting 06C-12C on 3rd,

DRIVES connecting 6D-12D on 4th

I know it is incorrect, because 05A-12A are directors, they should not be on the same engine. One engine only has 2 directors. I am confused.

Thank you for your patience!

emcmagic, you are correct.  Each director board has 4 FA CPUs (1 per 2 ports).

Hi rohang,

Your diagrams and descriptions look great, they cleared my mind. Your help is greatly appreciated here!

I would like to take this opportunity to extend my original question, if you don't mind.  it is about FA directors.

The front ports will be located on the same directors on each engine as DA directors. They are located on CPU E,F,G, and H. Each CPU has 2 FA ports, and therefore on VMAX-20, we have 2(directors) x 4 (CPUs) x 2(ports) x 4(engines) = 64 FA ports.

Is my statement correct?

the statements are correct, emcmagic. A total of 64 FA ports for your 4-engine VMAX.

regards.