Storage Pool

With every passing year, enterprises grow increasingly dependent on storage devices to run their business operations. This is clearly evident from a market report that says that the storage device market size will rise from USD 247 billion to USD 777 billion in 2030, an effective CAGR of 17.8% in just seven years.

This clearly highlights that data is expanding and will continue to expand in an exponential fashion.

With these copious amounts of data, the focus cannot only be on merely expanding storage to accommodate growing amounts of data. It's imperative that data is effectively managed, so you can access data flexibly with proper backup and redundancy systems in place to counter any loss. This can be achieved with the help of storage pooling.

What is a LUN in a SAN?

A storage pool is a type of storage provisioning. It helps you distribute the collective storage capacity of your disk drives logically. After segregating the storage capacity into different pools, you can carve out storage for each application and associate a logical unit number (LUN) for it. A LUN is simply used as an identifier.

The capacity of each storage LUN (associated to a pool) can be carved out from a single disk or a combination of multiple disks. The workload or application will consider a LUN as a single physical storage entity. This makes storage management easier.

Storage pool vs. RAID

A redundant array of independent drives (RAID) is again a storage provisioning concept and is primarily useful to manage storage arrays for increased performance and to ensure data security.

There are different types of levels or RAID configurations (RAID 0-6) that can be applied. A RAID configuration can be applied to a maximum of 16 drives. You can choose a configuration based on your requirements and the type of data being stored.

For example, for data backup and security, RAID 6 can be used, which can withstand multiple drive failures. RAID 6 can be applied to a minimum of 10 disks and a maximum of 16 disks, two of which will used for parity. For better performance, RAID 5 can be used, which uses only one disk for parity.

RAID configurations can be implemented with the help of software or RAID controller hardware. A limitation of RAID is that it can be implemented for a maximum of 16 drives. Storage pools, on the other hand, can be implemented to hundreds of disk drives.

However, you cannot decouple RAID configurations when you pool storage and create LUNs. When you create a storage pool, you have to mention the RAID level as well. Usually RAID 5 or RAID 6 configuration is used.

Heterogeneous storage pool

Storage pools can be created by carving out storage from different types of storage drives such as Serial Attached SCSI (SAS), Flash, and Near Line SAS (NL-SAS), unlike RAID which can be applied to only one type of storage.

By pooling storage from a heterogeneous storage capacity, you can make data access flexible and quick. For example in a heterogeneous storage pool method, data that is frequently accessed will be stored in high-performance flash storage, and data that is rarely accessed will be stored in SAS storage.

Practical implementation of storage pooling

Maintaining a storage device for one server is simple, but it can be cumbersome when you have to install individual storage systems for hundreds of servers in an organization's data center.

The servers in a data center are generally used to host applications and workloads. When standalone storage devices are connected to a server, migration becomes a complex process, meaning when a workload is migrated from one server to another, the storage devices must also be exchanged. This is not feasible for enterprises.

Storage area network (SAN) helps companies with this challenge. In simple terms, a SAN helps you to connect your servers to the storage system. It consolidates the storage devices and forms a single storage system that helps servers access data from the SAN.

Utilizing storage pools and LUNs can be an effective way to manage SANs and provision storage to workloads in an enterprise. When it comes to creating storage pools, it is important to consider the following aspects:

Thin provisioning vs. thick provisioning

When creating LUNs from the storage pools, you need to provision the storage for each LUN depending on the application it caters to. Thick provisioning refers to allocating a fixed amount of capacity to the LUN. On the other hand, thin provisioning gives you the flexibility to allocate more capacity in the future as demand rises.

For example, say you thick provision a LUN with 100-GB. Now, say the workload demands only 50-GB; the remaining 50GB will still be considered a part of this LUN and it cannot be allocated to other applications in need.

But when you thin provision a LUN with 100-GB and the workload actually demands 40-GB, the remaining 60-GB can be allocated to other functions elsewhere, and later when the thin-provisioned LUN requires extra capacity, it can reclaim the needed storage on demand. This flexibility makes thin provisioning the go-to option and enables you to optimize your storage capacity. However, there is a caveat—if the thin-provisioned LUN is not provided the required storage in future during reclamation, it can make the LUN a read only LUN, so proper management is essential while provisioning.

Types of LUNs

The different types of LUNs include:

  • Mirrored LUNs: The data is copied in another physical drive for redundancy and backup.
  • Striped LUN: The data is written equally in all the available physical drives to ensure that the I/O operations are equally distributed across the disks and no disk is overused.
  • Striped LUN with parity: This is an extension of a stripped LUN with parity. The data is written across multiple drives, and parity information is also stored on multiple drives. When a particular physical drives fails, you can retrieve data from the parity disks.
  • Concatenating LUNs: The data from multiple LUNs is combined (concatenated) into one single LUN.

Storage vendors

There are multiple leading vendors that offer their own platform software to create storage pools and LUNs and manage them centrally. Some of the well known enterprise vendors are NetApp, Dell EMC, IBM, and Synology DSM.

When it comes to monitoring, narrowing down the focus on certain key performance indicators can give an overall picture of performance. LUN utilization, input/output operations per second (IOPS), and LUN bandwidth are some of the metrics that one can measure. The exact names of the metrics may vary from vendor to vendor.

Also, each vendor offers certain recommendations or best practices that should be adopted to ensure long-term device health. For example, certain vendors recommend using the same type of disk drives when creating storage pools.

Unified, multi-vendor storage monitoring with OpManager

Storage infrastructure is a fundamental component of IT, and the health of your storage devices has a huge impact on how your network performs. Over-utilized disks can directly impact your application performance, slowing them down as the application has to wait in a queue for a long time to access the data.

This is why consistent monitoring of your storage devices is so essential. Having a robust storage monitoring solution goes a long way in how your network performs and effectively propels your business forward.

ManageEngine OpManager is a renowned storage monitoring solution that supports a wide range of vendors, including well-regarded companies such as HPE, Dell EMC, IBM, NetApp, PureStorage, and Hitachi.

By enabling the storage monitoring add-on in OpManager, you'll gain centralized visibility on all your RAID devices. You'll be able to see how your storage capacity is pooled and view the the performance and utilization of your LUNs in a single window.

Storage Pools - ManageEngine OpManager

With alert-based monitoring, you can receive alerts whenever your storage metrics cross ideal levels.

OpManager supports both SSDs and HDDs and even monitors associated hardware metrics such as Fan Temperature and Battery Voltage.

Interested in learning more? Get a free and personalized demo or request a quote.



FAQs - Storage pools and LUNs

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