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Dell PowerFlex Solutions Design 2023 > The (Almost) Definitive Guide to PowerFlex Sizing & Other Matters > Flashcards

The (Almost) Definitive Guide to PowerFlex Sizing & Other Matters Flashcards

1
Q

What are the restrictions for software only PowerFlex?

A

only for existing ScaleIO customers (since most original ScaleIO deployments were SW only) or net new customers purchasing over 2 million in capacity licensing over 2 years

RPQ required

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2
Q

How much RAM is required per SDC?

A

50MB

also consumes very low host CPU

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3
Q

What is the SDSs responsibilities?

A

consuming local storage devices within server

making sure second copy of data is written to a different host before acknowledgement back to the SDCs

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4
Q

How much RAM does an SDS consume?

A

500MB-12GB per host (with MG layout)

very little CPU workload

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5
Q

How many vCPUs/cores are allocated for an SDS?

A

8-12

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6
Q

What protection level do protection domains have?

A

only one simultaneous node failure can occur within a PD

fault sets allow for multiple host failures but are typically not required

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7
Q

What should be the max number of SDSs to put in a PD?

A

30 SDSs per protection domain

to maintain 6 9s of availability

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8
Q

What is the max number of devices in a storage pool?

A

300 devices

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9
Q

How is data layed out in FG and MG pools?

A

MG - 1MB
FG - 4KB

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10
Q

What are the two performance profiles on PowerFlex?

A

High

Compact

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11
Q

What is the high performance profile?

A

all flash nodes

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12
Q

What is the compact performance profile?

A

HDD nodes

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13
Q

What is the SVM?

A

Storage VM

a VM for ESXi environments that runs CentOS - runs the SDS and LIA components

typically maps the local storage devices and RAID controller to the host through DirectPath IO

NVMe drives should use RDM

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14
Q

What is the main different between high and compact performance profile?

A

amount of CPU resources given

compact - SVM given 2 vCPUs/cores

high - SVM given 8 vCPUs/cores

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15
Q

What is the performance profile recommendation for PowerFlex?

A

configure High for both SSD and HDD - the new default setting

version 3.5 allows now up to 12 vCPUs and 12 SDS threads for FG pools

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16
Q

What is the recommendation specific to performance profile and CloudLink?

A

when using CloudLink D@RE increasing SVM by another vCPUs is considered best practice (from 8 to 12)

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17
Q

What is the all-flash performance of PowerFlex?

A

each SSD can provide about 80,000 Read IOPS

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18
Q

What is the max performance of SDS?

A

250,000 IOPS for reads
100,000 IOPS for writes (due to second copy being required it’s slower)

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19
Q

What happens after you hit the IOPS limit of an SDS?

A

can add more SSDs for higher large block performance

will not be able to improve small block performance

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20
Q

What is the typical performance of an SDC?

A

500,000 read or write IOPS if connected to multiple SDSs

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21
Q

What is the bandwidth performance of PowerFlex?

A

for large block IO - can saturate 200GbE per node to deliver 20GB/s of bandwidth for SDCs per node (2 x 100GbE interfaces)

SDS normally max out around 10GB/s per node when using NVMe and 7-8GB/s when using SSD

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22
Q

What are the latency metrics of PowerFlex?

A

0.2-1ms w/ All Flash and very high IOPS

100-200 microseconds w/ NVMe and low queue depth IO profiles

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23
Q

How does PowerFlex Manager run?

A

runs an an ova. VM on dedicated management nodes external to PowerFlex workload nodes

can also be managed through REST API

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24
Q

What is a recommendation for sizing Oracle environments?

A

often beneficial to have compute-only nodes to extract the most value out of expensive licenses which are by the core

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25
Q

What is the only node type that can support GPUs?

A

R740xd

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26
Q

Why do you need to configure minimum 10% spare capacity?

A

to maintain protection of a single node failure

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27
Q

What is the rule when sizing for performance?

A

the more nodes the better

size with smaller drives to get more nodes

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28
Q

Why is bandwidth and latency better on NVMe devices rather than SSDs?

A

IO does not need to go through the HBA330 controller and instead goes directly to the CPU

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29
Q

How is PowerFlex licensed?

A

per raw TiB - perpetual

can carry it over to net new hardware to reduce TCO

licenses per customer not per site or per cluster

30
Q

How many tiers of licensing are their?

31
Q

What is tier 1 licensing?

32
Q

What is tier 2 licensing?

A

101-250TBs

33
Q

What is tier 3 licensing?

A

251-500TBs

34
Q

What is tier 4 licensing?

A

501-1000TBs

35
Q

What is tier 5 licensing?

A

1001-5000TBs

36
Q

What is tier 6 licensing?

A

5001-10000TBs

37
Q

What is tier 7 licensing?

A

10001-20000TBs

38
Q

What is tier 8 licensing?

A

20001-40000TBs

39
Q

What is tier 9 licensing?

A

40001-60000TBs

40
Q

What is tier 10 licensing?

A

60001-100000TBs

41
Q

What is tier 11 licensing?

A

100000+TBs

42
Q

What is the RPO for asynchronous replication?

A

30 seconds for version 3.5

43
Q

How much RAM is required for SDR?

A

22GB RAM per node

44
Q

What is the connectivity recommendation for SDR?

A

25GbE or faster

45
Q

Where is replication enabled on PowerFlex?

A

at the protection domain level

SDRs must be present in each PD if any volumes from that PD need to be replicated

46
Q

What are the replication design choices for PowerFlex?

A

SDR only enabled on one PD

enable only Partial SDRs per PD

enable max nodes w/ SDR

47
Q

What is the SDR only enabled on one PD option?

A

allow only for volumes on that PD to be replicated

if this PD is down for maintenance replication will be unavailable during that time

48
Q

What is the enable only partial SDRs per PD?

A

will allow all PDs to be able to participate in replication activities

if the workload is low at least 3 nodes per PD need to be running the SDR

design may require an RPQ

49
Q

What is the enable max nodes with SDRs?

A

current supported max SDR per cluster is 64 (version 3.5)

50
Q

What is the relationship between WAN bandwidth and replication?

A

replication performance most often limited by the WAN bandwidth

need to properly size WAN bandwidth and journal capacities

51
Q

What is the relationship between local bandwidth and replication?

A

bandwidth consumption w/ replication is 3x higher than without which is why additional bandwidth is required

8K workload EX:
normal write = 16K (2 copies of 8K)
replicated write = 48K

52
Q

What is the networking recommendation for PowerFlex?

A

use multipathing whenever possible along with LACP

LACP is first layer of protection and then there are multiple VLANs running on top providing IP Multipathing

53
Q

What is important for OLTP workloads?

A

require high IOPS and low latency

54
Q

What is important for OLAP workloads?

A

high bandwidth

55
Q

How is SDS installed in a preconfigured ESXi environment?

A

deploying SVM

56
Q

How does the MDM interact with the SDS and SDC?

A

interacts asynchronously using a separate data path and will not impact performance

57
Q

What do larger storage pools provide?

A

wider striping by spreading IOs across more devices - benefits apps w/ high IO concurrency and bandwidth requirements

more flexible shared capacity for multiple volumes by providing larger pool for volume allocation

faster rebuild time - more spindles typically means faster rebuilds

58
Q

What do smaller storage pools provide?

A

better protection from multiple drive failures

better guaranteed IOPS by provisioning SPs for apps that require guaranteed performance

59
Q

How is physical and logical data protection done on PowerFlex?

A

PDs provide physical separation and SPs provide logical separation

SDCs can access volumes regardless of PD or SP

60
Q

What is important to know before implementing fault sets?

A

can only create and configure fault sets before adding SDSs to the system

configuring them incorrecty may prevent the creation of volumes since an SDS can only be added to a fault set during the creation of the SDS

61
Q

What are the rules for fault sets?

A

data mirroring for all the devices in the fault set must take place in a separate fault set

minimum of 3 fault sets are defined

62
Q

Where is spare capacity implemented in PowerFlex?

A

the SP level

63
Q

What is the relationship between rebuild/rebalance operations and bandwidth?

A

rebuild/rebalance can affect the available bandwidth for client traffic if the physical ports are shared between SDC and SDS nodes

64
Q

What is the networking recommendation when it comes to rebuild/rebalance operations?

A

Have multiple interfaces connected to allow front end client traffic to flow unimpeded by back end operations

back end rebuild/rebalance can compete w/ client bandwidth if only over a single interface

65
Q

How can interfaces be designated in PowerFlex?

A

SDC to SDS communication

SDS to SDS traffic

66
Q

What is the networking recommendation if you only have a single interface connection per node?

A

limit client bandwidth to keep from overloading system while a rebuild/rebalance occurs

67
Q

How can MDMs be mounted in PowerFlex?

A

can be located anywhere in the system and don’t require dedicated nodes

in larger configurations they should be distributed for availability reasons

EX: in multirack config they each (3-5) should be placed in different racks and different fault units

68
Q

What is ideal network configurations for MDM connectivity?

A

all on the same subnet for minimal latency

69
Q

What is the networking recommendation for smaller configurations?

A

running full mesh architecture w/ SDSs and SDCs sharing a non-routed subnet (access-agg)

70
Q

What is the networking recommendation for larger configurations?

A

leaf-spine

71
Q

Why should you size for multiple storage pools initially?

A

allows customer growth without having to provision multiple storage pools and keeps them balanced with respect to number of drives in them

Dell PowerFlex Solutions Design 2023 (11 decks)

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