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IMCx87
1 Copper

Block Alignment on VMAX All Flash 250F

Hi All,

During performance test with IOmeter, on our VMAX 250F, with 1.5TB of cache, two V-Bricks and 40 SSD disks.

We expected to view 200K IOPS and RT<1ms(Requirements of our RFP). But, when I do the test, we don´t see these numbers.

Only 180K [MAX] IOPS with 1.3/1.4 avg IOPS not sustained.

I noticed a lot of GM consumed, (Topic for another time.) because we created some TDEV´s and I noticed some good variation when we change the Align IO, to 1MB and we saw 290K IOPS and 0.8ms RT sustained.

Changing Align IO/partition Alingment is a good choice for pushing performance and decrease RT?

Thanks in advance.

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2 Replies
SKT2
4 Tellurium

Re: Block Alignment on VMAX All Flash 250F

What is the host OS where the alignment was performed?

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IMCx87
1 Copper

Re: Block Alignment on VMAX All Flash 250F

Hi my friend!

Our environment is based in:

4 ESXi Hosts with 4 VM´s on each host.

2 VM´s with Windows 2012

- 4vCPU;

- 16GB vRAM;


2 VM´s with Linux Red Hat 6.8

- 4vCPU;

- 16GB vRAM;


The 4 virtual machines are acessing disks with RDM and our frame is 80% Full.


One curious point are: When we changing the IO Alingment, we noticed a lot of cache hits, accurately 100% cache hit for 290K IOPS.


And additional info:

IOMeter config schema:

4 workers per VM

288GB of Working set of 9GB in 32 TDEV´s;

8 OiO / 70% Read & 30% Write 8KB Block;

Expected to reach 75% of cache hit!

Thanks!


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