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Dell PowerFlex Appliance with PowerFlex 3.x Administration Guide

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Calculate RAM capacity for medium granularity SDS

Use the formula provided in this procedure to calculate the required storage VM (SVM) parameters.

Prerequisites

Consider the following CPU requirements:

  • Storage data client (SDC): A maximum of 8 logical cores are supported.
  • Storage data server (SDS): The default setting for 3+ version is 8-9 logical cores. It is recommended to modify the default setting to 12 threads for PowerFlex storage-only nodes with fine granularity and CPUs with more than 12 physical cores.
  • Storage data client (SDR): 16 logical cores.
    NOTE:When CloudLink is configured, SVM must have a minimum of 12 vCPUs.

Consider the following SVM RAM and NVDIMM requirements:

  • MG SDS requires the least RAM.
  • FG SDS requires the maximum RAM.
  • Consider the NVDIMM fragmentation while calculating the NVDIMM capacity for non-HCI (where, NVRAM is interleaved).

About this task

See the following tables to verify SVM memory size on the medium granularity (MG) storage data client (SDC). Ensure that you have modified the memory allocation before starting the upgrade to PowerFlex 3.5.x, based on the table/formula. For calculation examples, see Example calculations for PowerFlex nodes.
Component CPU Memory (DRAM) Description
Storage data server (SDS) with fine granularity 10 vCPUs RAM capacity in GiB = 10 + ((100*Number of drives)+(550*Total drive capacity in TiB))/1024

PowerFlex Manager to set SDS thread count to 10, from default of 8.

Query: scli --query_performance_parameters --print_all --tech --all_sds|grep -i SDS_NUMBER_OS_THREADS

Set to 10: scli --set_performance_parameters --all_sds --tech --sds_number_os_threads 10

SDS with medium granularity 8 vCPUs SDS RAM capacity in GiB = 5+(210*Total drive capacity in TiB)/1024

Formula: SDS MG RAM_capacity_in_GiB = 5 ( (85+(25*over provisioning) )*Total drive capacity in TiB)/1024

Default over provisioning = x5

Storage data replication (SDR)

(FG: 10)

(MG: 8)

vCPUs

v3.6 - 12GiB

Ensure PowerFlex Manager sets "numa_memory_affinity=0" >> /opt/emc/scaleio/sds/cfg/conf.txt

Deploy SDR and SDS side-by-side

NUMA requirements for SVM/HC deployment

FG MD cache Not applicable FG MD cache: FGMC RAM in GiB = (Total drive capacity in TiB / 2)*4*Compression factor*Percent of metadata to cache Default: 2:1 compression and 2% hit ratio
MDM/TB 2 vCPUs 6.5 GiB This is the standard amount of resources allocated to the role.
LIA Not applicable 350 MiB This is the standard amount of resources allocated to the role.
SDC 8 threads 8 GiB Depends on the SDC consumption rarely hit 8 threads
Operating system Not applicable 2 GiB Embedded operating system based on CentOS in either PowerFlex storage-only node or SVM
CloudLink 2 vCPUs 4 GiB This is the standard amount of resources allocated to the role.
Spare RAM Not applicable 2 GiB It is recommended to always have additional RAM in the system in case of an unforeseen need to increase the RAM.
Total

MG: 8vCPU+2+2(CloudLink)=12 vCPU

FG: 10vCPU+2+2(CloudLink)=14 vCPU*Set SDS thread count to 10

MG+SDR: 8vCPU+8+2+2(CloudLink) = 20 vCPU*Set vNUMA+SDS NUMA

FG+SDR: 10vCPU+10+2+2(CloudLink) = 24 vCPU*Set vNUMA+SDS NUMA+SDS thread

MG: 8vCPU+2+2 (CloudLink)=12 vCPU

FG: 10vCPU+2+2 (CloudLink)=14 vCPU*Set SDS thread count to 10

MG+SDR: 8vCPU+8+2+2 (CloudLink) = 20 vCPU*Set vNUMA+SDS NUMA

FG+SDR: 10vCPU+10+2+2 (CloudLink) = 24 vCPU *Set vNUMA+SDS NUMA+SDS thread

This is the total of all the components that apply to the system.
Component NVDIMM capacity
FG pools

NVDIMM_capacity (GiB) = ((100*number_of_drives)+(700*capacity (TiB)))/1024

Steps

  1. Using the tables, calculate the required RAM capacity.
  2. Open the PowerFlex GUI using the PowerFlex management IP address and the relevant PowerFlex username and password.
  3. Select the Storage Data Server (SDS) from the Backend where you want to update the RAM size.
  4. Note the flex-data1-<vlanid> and flex-data2-<vlanid> IP addresses associated with this SDS by right-clicking the SDS and selecting Configure IP addresses. A window appears displaying the IP addresses used on that SDS for data communication. Use these IP addresses to verify that you powered off the correct PowerFlex VM.
  5. Right-click the SDS, select Enter Maintenance Mode, and click OK.
  6. Wait for the GUI to display a green check mark, click Close.
  7. In the PowerFlex GUI, click Backend and right-click on the SVM and verify the check box is deselected for Configure RAM Read Cache.
  8. Power off the SVM.
  9. In VMware vCenter, open Edit Settings and modify the RAM size based on the above table/formula. The SVM should be set as 12vCPU, configured at 12 cores and 1 socket regardless of CloudLink configured on the system.
    NOTE:If the underlying hardware cannot provide greater than the specified number of cores, the SVM should be constrained to a maximum of the number of physical cores available for scheduling reasons.
  10. Power on the SVM.
  11. From the PowerFlex GUI backend, right-click the SDS and select Exit Maintenance Mode and click OK.
  12. Wait for the rebuild and rebalance to complete.
  13. Repeat steps 6 through 13 for each SDSs in the PowerFlex system.

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