Midrange Storage Performance Planning: Storage Configuration Recommendations Flashcards
What are the supported types of pools in Unity XT?
dynamic and traditional
pools are preset to dynamic unless specified by admin
When would you want to have separate storage pools on the same Unity system?
separate workloads with different IO profiles
separate pools where FAST Cache is and isn’t active
dedicate resources to meet specific performance goals
separate resources for multitenancy
What is the recommended free capacity for a storage pool to maintain operations in a Unity XT?
10% free capacity
system automatically invalidates any snapshots or replications if free capacity is less than 5%
When does a Unity XT raise alerts for storage pools?
when there’s less than 70% free capacity
What are dynamic pools in Unity XT?
apply RAID to groups of drive extents from drives within the pool
allow for more flexibility and easier management
What are the dynamic pool options on Unity XT?
Single Tier
Multitier - pool consisting of combination of drive types
What type of pools does UnityVSA have?
only traditional pools
How do dynamic pools work in Unity?
combines the drives of the same type into a drive partnership group
at physical disk level systems splits disks into identical portions called drive extents
drive extents grouped into drive extent pool
drive extent pool used to create RAID extents
RAID extents grouped into RAID groups
What is the role of drive extents in Unity dynamic pools?
hold a position of a RAID extent or used for space space in case of rebuild
What is a RAID extent in Unity dynamic pools?
collection of drive extents
selected RAID type/width determine number of drive extents within a RAID extent
each one contains single drive extent from a specific number of drives equal to the RAID width
What is the result of the dynamic pool process in Unity?
creates a single private LUN for each RAID group by combining pieces of all RAID extents and striping them across the LUN
LUN partitioned into 256MB slices
How much spare space can you allocate in Unity dynamic pools?
up to 2 spares per 32 drives
unbound drives of appropriate type can also be used in rebuild
What is true about the relationship between dynamic pools and performance?
there is no performance or availability advantage to using smaller RAID widths with dynamic pools
What are the recommendations for drive minimums for different RAIDs in dynamic pools?
RAID 5 - 14 drives
RAID 6 - 17 drives
How does spare space work with dynamic pools?
each drive extent pool reserves a specific percentage of extents on each disk as spare space
percentage of reserve capacity dependent on drive type and RAID type applied to the drive
What happens if there’s a drive failure within a dynamic pool?
spare space within the pool is used
handled automatically
What is true about spare space and system capacity?
not counted towards usable capacity of the system
How much reserve space if in a dynamic pool at one time?
for every 32 drives of the same type within a pool there’s enough spare space to build back the largest drive in the pool
How does dynamic pool expansion work in Unity XT?
can expand up to the system limits by one or more drives
new drive partnership group is created if the number of drives added exceeds maximum size of 64 drives
When is expansion of a dynamic pool not allowed in Unity XT?
if number of drives being added is not enough to fulfill the minimum drive requirements
What is the minimum number of drives to start a new drive partnership group?
RAID width + set spare space reservation (1-2 drives)
What does adding drives within a drive partnership group do?
causes drive extents to rebalance across the new space
What happens when you add a single drive to a dynamic pool or a number of drives that is less than the RAID width of the pool?
system identifies extents that must be moved off drives to new drives as part of rebalancing process
frees up capacity on corresponding drives
What is the PACO feature on Unity XT?
proactive copy
enables disks to actively copy to a hot spare
What happens if you add a single drive and the spare capacity boundary is crossed on a dynamic pool?
none of that drive’s capacity is added to the usable capacity of the pool
What is the process of adding multiple drives to a dynamic pool?
much faster than single drive add on
expansion process creates drive extents
system creates RAID extents and RAID groups and makes space available to users
What is true about mixing drives in dynamic pools?
drives of same type but different capacities can be mixed
not recommended - can’t do different drive types in same pool
What happens when a new drive type is added to the system?
pool must be expanded with a minimum number of drives
must satisfy the RAID width + set spare capacity
What is a traditional pool in Unity storage?
storage pools whose tiers are configured with traditional RAID groups
How do you expand traditional pools in Unity?
only by adding RAID groups
What is max number of drives you can have in a traditional pool in Unity?
16
How can you configure traditional pools in Unity?
heterogenous
homogenous
How does a heterogenous traditional pool work in Unity?
RAID group of both drive sets created
Private LUN created for each RAID group
private LUNs split into continuous array slices that are 256MB - hold user data and metadata
once private LUNs partitioned into slices they are consolidated into single pool called slice pool
What is the relationship between FAST VP and heterogenous traditional pools in Unity?
moves slices to various tiers
When are homogenous pools recommended in Unity?
for applications with limited skew - more predictable performance
What are the RAID protection levels recommended by Dell for traditional pools?
RAID 5 - extreme performance/performance tiers
RAID 6 - capacity tier
When does Dell recommend smaller RAID widths in traditional pools?
when configuring the same number of drives
smaller widths provide best performance/availability
What is the recommended configuration for customers that want a RAID 1/0 in their Unity traditional pools?
1+1
offers better performance and flexibility with same availability
How is spare space allocated with traditional pools in Unity?
use hot spares
1 hot spare every 31 drives
replaces faulty drive with same type and same or higher capacity drive
What are important notes about all flash pools in Unity XT?
snapshots and replication operate more efficiently with AF pools
data reduction only enabled in AF pools
no FAST Cache/FAST VP
use only single drive size/RAID width in AF pools
What is the drive size and width necessary for Unity XT AF pools?
1.6TB SAS Flash 3 w/ RAID 5 (8+1)
What are the block storage resources supported by Unity XT?
LUNs
Consistency Groups
VMFS Datastores
vVol
What is a LUN?
logical unit representing a piece of block storage that is allocated to a host
can be allocated to multiple hosts if coordinated through a set of clustered hosts
What is a consistency group?
addressable instance of LUN storage that can contain one or more LUNs (up to 50)
associated to one or more FC or iSCSI hosts
snapshots of consistency groups apply to all LUNs in the group
What are vVols?
virtual volumes
storage objects that are provisioned automatically by a VMWare framework to store VM data
What are protocol endpoints?
establish a data path between ESXi host and respective vVol datastores
What storage object does Unity XT provision by default and why is it recommended by Dell?
creates thin storage objects automatically but supports thick LUNs also
provide the best capacity utilization and are required for most features
What features require thin storage objects to be used by Unity XT?
data reduction
snapshots
asynchronous replication
What configuration does Dell recommend for best capacity utilization in Unity XT?
configuring objects at least 100GB in size - preferably 1TB
What is a Powerstore volume?
single unit that represents a specific quantity of block storage that can be standalone or associated with a volume group
What is the role of Powerstore volumes?
manage partitions of block storage resources so that the host system can mount and use these resources
How are volumes created on Powerstore?
one volume or many can be created at a time
resource balancer automatically determines which appliance in the cluster the volume is provisioned
What is the role of thin provisioning?
allows multiple storage resources to subscribe to a common storage capacity
allocates an initial quantity of storage - represents maximum capacity to which storage resource can grow without being increased
What is the maximum and minimum size of storage volumes in Powerstore?
1MB - 256TBs
What is every volume given in Powerstore?
a LUN
What is a volume group in Powerstore?
logical container for a group of volumes
volume can only be member of one volume group at a time
What is the purpose of a volume group in Powerstore?
provides single point of management for multiple storage resources that work together as a unit
How are volume groups treated by the Powerstore system?
treats the volume group as a single entity
What is a NAS Server with Powerstore?
virtual file server that provides file resources on the IP network and to which NAS clients connect to
allow access over NFS and SMB and FTP and SFTP
What is a filesystem and how does Powerstore support them?
manageable storage object for file based storage with a specific size and file access protocols
Powerstore supports file system snapshots and thin clones of file systems
How does Powerstore store containers?
store them and contain VMWare vVols
containers have 1:1 mapping w vVol datastories
How does Powerstore communicate with VMWare for storage container storage?
communicates w/ vCenter server through VASA protocol
communication established through protocol endpoints
What block protocols does Powerstore support?
FC, NVMe/TCP, NVMe/FC, iSCSI
hosts must access storage only using one of these protocols at a time
What is dynamic node affinity in Powerstore?
block storage resources are dynamically rebalanced between nodes
What are performance policies in Powerstore?
all block storage have a defined performance policy
by default this is set to medium
devotes less resources to low performance policy volumes during times of high utilization
How are NAS servers distributed on Powerstore?
single NAS server uses compute resources from only one node of the Powerstore
recommended to create at least two NAS servers so resources from both nodes contribute to file performance
