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VMware vSphere shared storage guide

Eric Siebert, Contributor

You can use VMware vSphere without a shared storage device, but it limits the amount of advanced features that you can use with it. Certain features in vSphere require that a virtual machine (VM) reside on a shared storage device that is accessible by multiple hosts concurrently. These features include high availability (HA), Distributed Resource Scheduler (DRS), Fault Tolerance (FT) and VMotion, which provide high/continuous availability as well as workload load balancing and live migration of virtual machines. For some storage administrators, these features may only be nice to have, but they are also essential for many IT environments that cannot afford to have VMs down for an extended amount of time.

AFFORDABLE SHARED STORAGE OPTIONS FOR VMWARE VSPHERE TABLE OF CONTENTS

VMware vSphere shared storage explained
Drobo
Hewlett-Packard
Iomega
Netgear
QNAP
Synology
Thecus
Table of vSphere shared storage devices for SMBs
How do you know which shared storage option is right for your SMB?

VMWARE VSPHERE SHARED STORAGE EXPLAINED

A few years ago, VMware shared storage typically meant using a Fibre Channel (FC) SAN, which was expensive, required specialized equipment and was complicated to manage. In recent years, other shared storage options that utilize standard network components to connect to storage devices have become popular and make for affordable, easy-to-use shared storage solutions. The protocols used for this are iSCSI and NFS, both of which are natively supported in vSphere. The performance of NFS and iSCSI are similar, but both can vary depending on a variety of factors including the data storage device characteristics, network speed/latency and host server resources. Since both protocols use software built into vSphere to manage the storage connections over the network there is some minimal CPU resource usage on the host server as a result.

No extra hardware is required on a vSphere server to connect to a shared storage device using iSCSI or NFS, but it is recommended to have a dedicated network for this traffic. This includes dedicated NICs in the host server as well as a dedicated network switch that is isolated from the rest of the normal virtual machine network traffic. Additionally for iSCSI there are special network adapters (hardware initiators) available that have a TCP/IP Offload Engine (TOE) in them that offloads the iSCSI protocol processing from the host server which reduces the CPU overhead on the host.

The types and capabilities of affordable VMware vSphere shared storage options vary from simple, very low-cost units with limited features and expandability to more expensive units with more features and capacity. While just about any iSCSI/NFS shared storage device will work with vSphere, it is recommended to use one that is listed on the vSphere Hardware Compatibility Guide. While storage devices not listed on the Hardware Compatibility Guide will usually work, VMware will not provide technical support for any issues that are directly related to the storage device not listed on their compatibility guide; they will instead direct you to contact the manufacturer of the storage device.

The units listed in this article are suitable for SMBs that have limited budgets and want to take advantage of some of the advanced features in vSphere that require shared storage. Even if your budget is only $1,000, you can still get a unit that will provide satisfactory performance when using vSphere. All you have to do is connect these units into your existing network and you're quickly up and running. You just need to make sure you have a VMkernel port group configured on a vSwitch, and if you're using iSCSI you just enable the built-in iSCSI initiator. In addition, these units all have simple Web interfaces that are used to configure the storage device; no complicated storage area network (SAN) knowledge is needed to set them up.

Now let's take a look at some affordable shared storage devices available to use for VMware vSphere. These low-cost shared storage devices all retail for under $US5,000, use iSCSI and/or NFS interfaces, and range from smaller two hard drive standalone units up to larger 12 hard drive rack mount units. In addition, the vendors listed here all have some models listed on the vSphere Hardware Compatibility Guide.

DROBO

Data Robotics' Drobo offers a number of shared storage devices ranging from their entry-level Drobo model up to the Drobo Elite model. The low-end models such as the Drobo and Drobo S do not offer iSCSI or NFS support so are not suitable for use with vSphere. The high-end models, the Drobo Pro and Drobo Elite, both support iSCSI, but note that only the Drobo Elite is listed on the vSphere HCG. There is an additional model that was recently released called the Drobo FS which has support for DroboApps that can be installed on the device. There is also an NFS application available that could be utilized to connect vSphere hosts to it.

In addition to supporting standard RAID levels, the Drobo units also use a unique technology, BeyondRAID, which has features not found in traditional RAID and allows for mixed drive sizes in a RAID group.

HEWLETT-PACKARD

In addition to its enterprise-class storage devices, Hewlett-Packard (HP) Co. has a more affordable option, the HP StorageWorks X1000 series storage devices. The lower end X300 and X500 line of storage devices are not suitable to use with vSphere because they run Microsoft Windows Home Server, which does not support iSCSI or NFS connections.

The X1000 series of storage devices all run Microsoft Windows Storage Server 2008 that supports both the iSCSI and NFS protocols. The X1000 models include the X1400, X1500, X1600 and X1800, which are all 2U rack mount units except for the X1500 which is a tower unit that HP recently released. The models can all have their capacity increased with optional external disk enclosures. All units have redundant power supplies (optional on the X1500) and also have hot-swappable hard drives. Essentially, the X1000 storage devices are HP servers (i.e., DL380) that have Microsoft's Storage Server 2008 OS installed on them that is a special OS optimized as a storage operating system. As a result, you can login and interact with the OS and add memory or expansion cards to the server. Because all the HP StorageWorks models feature hot-swappable drives, you must purchase the special HP model drives that come with the hot-swappable drive sled. The X1400, X1600 and X1800 are all listed on the vSphere HCG, but the X1500 is not yet listed. However, the X1500 was just released and should be added to the vSphere HCG soon.

The HP models are more expensive than some of the other affordable storage devices but they have many advanced features and a solid architecture that is based on HP's DL servers.

IOMEGA

Iomega is owned by EMC Corp. and offers several affordable shared storage devices from their small two-drive ix2-200 unit all the way up to their newly released twelve-drive ix12-300r unit. The Iomega models offer tremendous value with many great features and they all support iSCSI and NFS. Because of EMC's strong relationship with VMware, all of the Iomega models are listed on the vSphere HCG. The Iomega models are available with disks in varying configurations. However, you must use Iomega hard drives because they use a proprietary drive sled with a special security screw head that makes it difficult to remove from the drive. The ix4-200d is one of their most popular units, while the 4 TB ix12-300r adds many features like redundant power supplies, bigger cache and four network ports.

NETGEAR

Netgear sells a wide variety of shared storage devices in its ReadyNAS family from their small ReadyNAS Duo model up to their largest model, the ReadyNAS 4200. The ReadyNAS models all have advanced features such as the ReadyNAS Vault feature that can replicate data to another ReadyNAS device or FTP site. Most of the models support both iSCSI and NFS protocols as well as many conventional RAID levels. They also support Netgear's proprietary X-RAID2 that allows for easy expansion as well as using different drive sizes in the same RAID group. Most of the ReadyNAS models are listed on the vSphere HCG. Most of the ReadyNAS models can be purchased with or without disks.

QNAP

QNAP Systems has a very large line of affordable shared storage devices from small two-drive units to larger eight-drive tower and rack-mount units, with 11 models listed on the vSphere HCG. All of the units support both iSCSI and NFS and many also include advanced features that are listed in this comparison chart. The QNAP shared storage devices all have hot-swappable drives, provide the drive sleds and support third-party hard drives. You can also expand or increase RAID levels while the unit is running.

A convenient feature that QNAP has is called a Virtual Disk Drive (VDD) that allows the QNAP unit to connect up to eight external iSCSI targets and present them as one stacked disk. The QNAP device becomes the stack master for the other iSCSI targets, and servers that connect to the QNAP see one stacked disk instead of the multiple iSCSI targets that make up the stack. Some additional features include support for IPv6, multiple NIC bonding modes, LUN masking, Wake-on-LAN and Active Directory integration. The only units with redundant power supplies are the eight-bay rack mount units (TS-809U-RP and TS-859U-RP). The prices range from $599 for the smaller two tower drive units to $2,099 for the larger rack units. The QNAP units all come without drives, but you can add any brand/size SATA drives that you want to them.

SYNOLOGY

Synology offers a wide range of more than 10 affordable shared storage devices ranging from simple one-drive units all the way up to five-drive units that can be further expanded with an add-on five-drive expansion unit. All DiskStation models have a rich selection of features and they all support both iSCSI and NFS. Synology also includes its DiskStation Manager Web-based interface that is used to manage the DiskStation units and has some impressive features such as Active Directory integration, link aggregation, built-in firewall, resource monitor and a wide variety of backup options. In addition to supporting the normal RAID levels, Synology has its own Hybrid RAID that supports using drives of varying sizes in a RAID group. The only DiskStation unit currently listed on the vSphere HCG is their high-end DS1010+ model, which is priced at $999. However, while not listed on the HCG the DS410 and RS409+ units are also good units to use with vSphere. All of the Synology units can be purchased without hard drives and there are also some packages available that have drives included.

THECUS

Thecus Tech Corp.has a large family of storage devices with seven of them listed on the vSphere HCG. All of the units support iSCSI and NFS and have many advanced features that you would normally find on more expansive SANs. This includes support for snapshots, data replication using the company's proprietary Nsync, dual disk modules, redundant power supplies, link aggregation and online RAID migration and expansion.

Many of the Thecus shared storage devices support a 10 Gb Ethernet adapter to the single PCIe x8 expansion slot that is present in some models. All models support using SATA disks but they have a few models (N7700SAS and N8800SAS) that support using faster SAS disks as well. The Thecus models can be attached to one another in a stacked mode to provide greater expandability and they also support thin provisioning. The lower end Thecus N4200 device starts at $799 and goes up to $1,999 for the N8800PRO model. Also, the units are all available without drives so you can add your own drives and all drives are hot-swappable.

TABLE OF VSPHERE SHARED STORAGE DEVICES FOR SMBS

The table below represents a breakdown of the shared storage devices from the vendors discussed previously, but this does not include all of the models available from each vendor. The table shows the number of drive bays, whether they are rack-mountable or standalone tower units, whether they support iSCSI and NFS or not, the number of network connections, how much memory they have, the maximum internal capacity when using the largest drives, if they are on the vSphere HCG or not and the approximate retail price of the lowest end unit.

Device

# of bays

Rack

iSCSI

NFS

# of network connections

Mem

Max. raw
capacity

HCG

Retail - All in $US

Drobo FS

5

No

No

Yes

1

N/A

10 TB

No

$699*

Drobo Pro

8

No

Yes

No

2

N/A

16 TB

No

$1,499*

Drobo Elite

8

No

Yes

No

2

N/A

16 TB

Yes

$3,499*

HP X1400

4

Yes

Yes

Yes

2

2 GB

8 TB

Yes

$3,795 *

HP X1500

8

No

Yes

Yes

2

2 GB

16 TB

No

$3,841 *

HP X1600

14/25

Yes

Yes

Yes

2

6 GB

12/24 TB

Yes

$4,997*

Iomega ix2-200

2

No

Yes

Yes

1

256 MB

4 TB

Yes

$249 (1 TB)

Iomega ix4-200d

4

No

Yes

Yes

2

512 MB

8 TB

Yes

$599 (2 TB)

Iomega ix4-200r

4

Yes

Yes

Yes

1

1 GB

8 TB

Yes

$1,499 (2 TB)

Iomega ix12-300r

12

Yes

Yes

Yes

4

1 GB

24 TB

Yes

$4,999 (4 TB)

Netgear ReadyNAS NVX

4

No

Yes

Yes

2

1 GB

8 TB

Yes

$1,099 (1 TB)

Netgear ReadyNAS Pro

6

No

Yes

Yes

2

1 GB

12 TB

Yes

$1,749 (1.5 TB)

Netgear ReadyNAS 2100

4

Yes

Yes

Yes

2

1 GB

8 TB

Yes

$1,699 (2 TB)

Netgear ReadyNAS 3200

12

Yes

Yes

Yes

2

4 GB

24 TB

Yes

$4,999 (6 TB)

QNAP TS-259 Pro

2

No

Yes

Yes

2

1 GB

4 TB

Yes

$649*

QNAP TS-459 Pro

4

No

Yes

Yes

2

1 GB

8 TB

Yes

$999*

QNAP TS-809 Pro

8

No

Yes

Yes

2

2 GB

16 TB

Yes

$1,749*

QNAP TS-809U-RP

8

Yes

Yes

Yes

2

1 GB

16 TB

Yes

$2,099*

Synology DS410

4

No

Yes

Yes

1

512 MB

8 TB

No

$499*

Synology RS409+

4

Yes

Yes

Yes

2

1 GB

8 TB

No

$1,359*

Synology DS1010

5

No

Yes

Yes

2

1 GB

10 TB

Yes

$999*

Thecus N4200

4

No

Yes

Yes

2

1 GB

8 TB

Yes

$799*

Thecus N7700+

7

No

Yes

Yes

2

2 GB

14 TB

Yes

$1,099*

Thecus N8800PRO

8

Yes

Yes

Yes

2

4 GB

16 TB

Yes

$1,999*


*Price without drives

As you can see, there are many affordable shared storage options that you can use with vSphere. Just remember when selecting a model to make sure it will be able to handle your virtual machine workloads. As a general rule of thumb, the more money you spend on a unit the more features and better performance you will receive. The units listed here should be able to meet the needs of light to moderate workloads, but if you have more demanding workloads you should consider the next tier of shared storage devices that range from $5,000 to $12,000, such as the HP MSA or NetApp FAS2020.

HOW DO YOU KNOW WHICH SHARED STORAGE OPTION IS RIGHT FOR YOUR SMB?

Overall, when choosing a shared storage device, keep in mind several factors. First, choose between iSCSI and NFS; they offer similar performance but have different characteristics, and many units offer both and they are both fairly easy to set up. My preference is iSCSI, but choose the one you are most comfortable with. Or try and benchmark each using Iometer running inside of a VM to see which one performs best in your environment.

Second, when sizing the units don't forget the RAID overhead; a unit with four 1 GB drives will only give you about 2.8 GB usable space. Try not to mix drive speeds/sizes; while many of these units offer special RAID technology to use different size drives in a RAID group you will loose performance and disk space by doing that. Also, many of these units have some great advanced features like being able to grow an existing iSCSI volume, setup CHAP security, monitoring via SNMP and more. Go through the feature lists to make sure the unit you are interested in has everything you want.

Third, don't forget about expandability. Many of these shared storage devices can attach to expansion units that gives you more space when you outgrow the unit. Many of these units support connecting USB hard drives to them, but don't even think of trying it; the speed of USB is slow compared to the native disk bus, and it would be unusable to run virtual machines on.

Finally, make sure you purchase a shared storage device based on your workload demands. Don't buy a cheap two-drive unit and run a busy SQL Server VM on it. The more spindles in your RAID group the better performance you will have, but remember these are low-cost units that will not handle a large amount of IOPS, and are better suited for virtual machines in the SMB area with light/medium workloads.

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