Comparing EMC, HDS and NetApp storage arrays – Part 2 (NAS Features)

EMC, HDS and NetApp are leaders in storage technology and the good news is that they are not carbon copies of each other. They have all made different architectural choices which means they each have their own set of strengths and weaknesses.

It is never going to be the case that one of these vendors is always the best and one is always the weakest, so the challenge for the storage buyer is to find the platform that is the best match for their organisations requirements.

This exercise is a real challenge, on paper all the products look fantastic, but as always the devil is in the detail. Just seeing if a product supports a particular feature is not enough, it all comes down to how well it has been implemented.

The general rule of thumb is that enterprise-class arrays (i.e. EMC VMAX and HDS VSP) implement a broad range of features to a very high standard. As you move to lower-cost mid-range platforms the feature set often remains more or less the same, but the individual features are not as sophisticated as the enterprise offerings.

Here at SNS we have spent many years designing, deploying and contrasting storage arrays from various vendors, which has put us in a good position to dig into the detail to see exactly how they compare.

We have decided to break this comparison into 3 sections – Block, NAS and Management & Integration. In this second post we will focus on comparing the NAS features:

Core ArchitectureEMC VNXHDS HNASNetApp FAS cDOTEMC Isilon
Unified NAS and Block HeadsNo (NAS Heads attach to Block Storage)No (NAS Heads attach to Block Storage)YesNo (Clustered NAS nodes with local storage)
NAS Heads per system1-81-823-144
Active/Active NAS HeadsNo (N+1)YesYesYes (All nodes are active)
NAS Head Storage Interconnects2 x 8Gbps FC2 or 4 x 8Gbps FCN/A20Gbps Infiniband between nodes
Hardware AccelerationNoYes (FPGA)NoNo
Administration/Quorum Server Physical Physical or VMNot RequiredNot Required
Clustered ArchitectureNo (Individual NAS Heads)No (Individual NAS Heads)Yes (Multiple HA Pairs with 10GbE Cluster Interconnect)Yes (With distributed file system)
Multi-Node Failure ProtectionNoNoNoYes (Up to 4 nodes)
Maximum Heads per ClusterN/AN/A4-24 (Up to 12 HA Pairs)144
Mirrored Write CacheNo (Block Storage Write Cache only) YesYesYes (Mirrors Writes to peer node)
Data Protection RAID provided by Block StorageRAID provided by Block StorageRAID-DP/4File segments striped across nodes
Extended Protection LevelsNoneNoneNoneN+1, N+2, N+3, N+4
File System Block Size8 KB4 KB or 32KB4 KB8 KB
Maximum File System Size16 TB256 TB100 TB 20 PB
Shrink File Systems in useNoYesYesYes
Maximum Capacity per Head256 TB4,000-32,000 TB240 TB-2,800 TBN/A
Single File SystemNoNoNoYes
Single Namespace across NAS Heads (CIFS and NFS)NoYesYesYes (Single File System)
Suitable for Tier 1 & 2 AppsYesYesYesNo (Does not provide very low response times)
Protocols & EfficiencyEMC VNXHDS HNASNetApp FAS cDOTEMC Isilon
ProtocolsNFS, CIFS, FTPNFS, CIFS, FTP, iSCSINFS, CIFS, iSCSI, FCoE, FCNFS, CIFS, FTP, HDFS, iSCSI (Not recommended)
CIFS/SMB Versions (1, 2, 3)YesYes Yes1, 2
NFS Versions (2, 3, 4, 4.1/pNFS)Yes2, 3, 43, 4, 4.1/pNFS2, 3, 4
Simultaneous multi-protocol (CIFS and NFS) file accessYesYesYesYes
NDMP Direct-attach (2 way) BackupYesYesYesYes
NDMP Remote LAN (3 way) BackupYesYesYesYes
NDMP Versions (2, 3, 4)YesYesYesYes
Block Level Post Process De-DuplicationNo (File level only)4 KB or 32 KB4 KB8 KB
Continuous De-duplication with Auto ThrottlingNoYesNoNo
Hardware Accelerated De-duplicationNoYes (FPGA)NoNo
CompressionYes (Post-Process)NoYes (Inline or Post-Process)No
Metadata TieringNoYesNo (Metadata can be cached using Flash Cache & Flash Pool)Yes
Policy based integrated File TieringNoNoNoYes
Policy based Tiering using stubs to internal, external and cloud storageYes (Requires EMC Cloud Tiering Appliance)YesYes (Requires 3rd party product)No
Snapshots, Backup and ReplicationEMC VNXHDS HNASNetApp FAS cDOTEMC Isilon
Snapshot performance impactYes (Copy-on-Write)No (Redirect-on-Write)No (Redirect-on-Write)Yes (Redirect-on-Write & Copy-on-Write both used)
Maximum Snapshots per File System96 Read Only
16 Writable
1,024 Read Only 256 Read/Writable1,024 Read/Writeable per folder
Writeable File ClonesYes (Writable Snapshots)Yes (Unlimited)Yes (255 per volume)Yes (Writable Snapshots)
Replication of SnapshotsNoNo for File-based Replication
Yes for Object-based Replication
Yes (SnapMirror Replication)No
Retain replicated snapshots for longer than primary snapshotsNoNoYes (SnapVault Backup)No
Remote Replica available for RestoresYesYes for File-based Replication
No for Object-based Replication
YesYes
Remote Replica available for Read/Write access (Using Writable Snapshot)YesYes for File-based Replication
No for Object-based Replication
YesYes
Snapshots can be used in place of D2D backup solutionNo for Applications
Yes for File Shares
No for Applications
Yes for File Shares
YesNo for Applications
Yes for File Shares
Integrated NAS ReplicationYes for Asynchronous
No for Synchronous (Replicates at the Block Level)
Yes for Asynchronous
No for Synchronous (Replicates at the Block Level)
Yes (Asynchronous only)Yes (Asynchronous only)
Minimum Replication Frequency1 Minute5 Minutes30 seconds5 Minutes
Replication impacts Performance (Due to changes being re-read)YesYesYesYes
Replication impacts Performance (Due to use of snapshots)Yes (Copy-on-Write Snapshot)No (Redirect-on-Write Snapshot)No (Redirect-on-Write Snapshot)No (Redirect-on-Write Snapshot)

As software updates or new platforms are released we will revisit the post and as always if you feel there are any inaccuracies please advise and we will check them out and update as appropriate.

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Mark Burgess has worked in IT since 1984, starting as a programmer on DEC VAX systems, then moving into PC software development using Clipper and FoxPro. From here he moved into network administration using Novell NetWare, which kicked-off his interest in storage. In 1999 he co-founded SNS, a consultancy firm initially focused on Novell technologies, but overtime Virtualisation and Storage. Mark writes a popular blog and is a frequent contributor to Twitter and other popular Virtualisation and Storage blog sites.
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About Mark Burgess

Mark Burgess has worked in IT since 1984, starting as a programmer on DEC VAX systems, then moving into PC software development using Clipper and FoxPro. From here he moved into network administration using Novell NetWare, which kicked-off his interest in storage. In 1999 he co-founded SNS, a consultancy firm initially focused on Novell technologies, but overtime Virtualisation and Storage. Mark writes a popular blog and is a frequent contributor to Twitter and other popular Virtualisation and Storage blog sites.

3 thoughts on “Comparing EMC, HDS and NetApp storage arrays – Part 2 (NAS Features)

  1. Thanks for the comparisons. I’m looking at a couple of these vendors and was hoping you can shed some light on what you’re saying about Isilon and tier 1/2 apps? I’d like to understand how you came to the conclusion that it’s not suitable and if there is any data that shows how high their latency. I appreciate your assistance.

  2. Hi Patrick,

    Isilon is designed to deliver high throughput across multiple streams spread across many nodes (i.e. it is great at media streaming).

    A single stream cannot match the low latency and high IOPS of a typical dual controller mid-range array (i.e. EMC VNX or NetApp FAS).

    In order to get anywhere near the IOPS and latency of a mid-range array you would need to have a lot more hardware – for example using Isilon for VDI would be a very bad idea.

    As always it is about architecture and as much as Isilon has some nice features there has to be a downside.

    Regards
    Mark

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