NetApp - Architecture

3/23/12 8:20 AMNetApp - Architecture

of 5http://www.datadisk.co.uk/html_docs/netapp/netapp_arch.htm#hardware

NetApp Architecture

The NetApp architecture consist of hardware, Data ONTAP operating system and the network. I have alreadyshown you a diagram of a common NetApp setup but now i will go into more detail.

Hardware

NetApp have a number of filers that would fit into any company and cost, the filer itself may have thefollowing

can be a Intel or AMD server (up to 8 dual core processors)can have dual power suppliescan handle up to 64GB RAM and 4GB NVRAM (non-volatile RAM)can manage up to 1176GB storagehas a maximum limit of 1176 disk drivescan connect the disk shelves via a FC loop for redundancycan support FCP, SATA and SAS disk driveshas a maximum 5 PCI and 3 PCI-express slotshas 4/8/10GbE support64bit support

The filer can be attached to a number of disk enclosures (shelves) which expands the storage allocation, thesedisk enclosures are attached via FC, as mentioned above the disk enclosures can support the following disks

FCP These are fibre channel disks, they are very fast but expensive

SAS Serial attached SCSI disks again are very fast but expensive , due to replace the FC disks

SATA Serial ATA are slow disks but are cheaper, ideal for QA and DEV environments

One note to remember is that the filer that connects to the top module of a shelf controls (owns) the disks inthat shelf under normal circumstances (i.e. non-failover).

The filers can make use of VIF's (Virtual Interfaces), they come in two flavors

Single-mode VIF1 active link, others are passive, standby linksFailover when link is downNo configuration on switches

Multi-mode VIF

Multiple links are active at the same timeLoadbalancing and failoverLoadbalancing based on IP address, MAC address or round robinRequires support & configuration on switches

Software



I have already touched on the operating system Data ONTAP, the latest version is currently version 8 whichfully supports grid technology (GX in version 7). It is fully compatible with Intel and AMD architectures andsupports 64bit, it borrows the idea's from FreeBSD.

All additional NetApp products are activated via licenses, some require the filer to be rebooted so check thedocumentation.

Management of the filer can be accessed via any of the following

Telnet or SSHFilerview (HTTP GUI)System Manager (client software GUI)Console cablesnmp and ndmp

Storage Terminology

When talking about storage you probably come across two solutions

NAS(Network Attached Storage)

NAS storage speaks to a file, so the protocol if a file based one. Data is made to be sharedexamples are

NFS (Unix)CIFS or SMB (Windows)FTP, HTTP, WebDAV, DAFS

SAN (Storage Area Network)

SAN storage speaks to a LUN (Logical Unit Number) and accesses it via data blocks, sharing isdifficult examples are

SCSIiSCSIFCAL/FCP

There are a number of terminologies associated with the above solutions, I have already discussed some ofthem in my EMC section

Terminology Solution Description

share/export NAS CIFS servers makes data available via shares, a Unix server makes dataavailable via exports

Drive mapping/mounting NAS CIFS clients typically map a network drive to access data stored on a storageserver, Unix clients typically mount the remote resource

LUN SAN Logical Unit Number , basically a disk presented by a SAN to a host, whenattached it looks like a locally attached disk.

Target SAN The machine that offers a disk (LUN) to another machine in other words theSAN

Initiator SAN The machine that expects to see the disk (LUN) the host OS, appropriateinitiator software will be required

One or more fibre switches with targets and initiators connected to them are

http://www.datadisk.co.uk/html_docs/emc/emc_architecture.html



Fabric SAN referred to as a fabric. Cisco, McData and Brocade are well know fabric switchmakers

See my EMC architecture section for more details

HBA SAN Host Bus Adapter, the hardware that connects the server or SAN to the fabricswitches. There are also iSCSI HBA's

Multipathing (MPIO) SANThe use of redundant storage network components responsible for transfer ofdata between the server and the storage (Cabling, adapters, switches andsoftware)

Zoning SAN

The partioning of a fabric into smaller subsets to restrict interference, addedsecurity and simplify management, it's like VLAN's in networking

See my EMC zoning section for more details

Below is a typical SAN setup using NetApp hardware

NetApp Terminology

Now that we know how a NetApp is configured from a hardware point of view, we now need to know how topresent the storage to the outside world, first some NetApp terminologies explained

Disk

This is the physical disk itself, normally the disk will reside in a disk enclosure, the disk will havea pathname like 2a.17

2a = SCSI adapter17 = disk SCSI ID

Any disks that are classed as spare will be used in any group to replace failed disks.

http://www.datadisk.co.uk/html_docs/emc/emc_architecture.html

http://www.datadisk.co.uk/html_docs/emc/emc_zoning_arch.html



Disks are assigned to a specific pool, also parity disks do not contain any data.

Raid Group (Pool)

Normally there are three pools 0, 1 and spare

0 = normal pool1 = mirror pool (if syncMirror is enabled)spare = spares disks that be used for growth and replacement of failed disks

Aggregate

A collection of disks that can have either of the below RAID levels, the aggregate can contain upto 1176 disks, you can have many aggregates with the below different RAID levels. An aggregatecan contain many volumes (see volumes below).

RAID-4RAID-DP (RAID-6) better fault tolerance

One point to remember is that a aggregate can grow but cannot shrink, the disadvantage withRAID 4 is that a bottleneck can happen on the dedicated parity disk, which is normally the firstdisk to fail due to it being used the most, however the NVRAM helps out by only writing to disksevery 10 seconds or when the NVRAM is 50% full.

Plex When a aggregate is mirrored it will have two plexes, when thinking of plexes think of mirroring.A mirrored aggregated can be split into two plexes.

Volume (Flexible) This is more or like a traditional volume in other LVM's, it is a logical space within an aggregatethat will contain the actual data, it can be grown or shrunk as needed

LUN The Logical Unit Number is what is present to the host to allow access to the volume.

WAFL

Write anywhere filesystem layout is the filesystem used, it uses inodes just like Unix. Disks are notformatted they are zeroed.

By default WAFL reserves 10% of a disk space (unreclaimable)

Snapshot

A frozen read-only image of a volume or aggregate that reflects the state of the new file systemat the time the snapshot was created, snapshot features are

Up to 255 snapshots per volumecan be scheduledMaximum space occupied can be specified (default 20%)File permissions are handled

Snapshots in NetApp world are very fast, basically it takes a snapshot of all the blocks that are associatedwith the files, this data is never actual changed, if a block is changed a new block is created, the snapshot stillpoints to the old block. NetApp has two products called SnapDrive and SnapManager that deal withconsistency problems where data has not actually been written to the disk but cached in memory buffers, youmight want to take a look at these products.



There are three additional replication products that can you can use

SyncMirror

real time replication of datamaximum distance of up to 35kmFibre Channel or DWDM protocolSynchronous

is used primarily for data redundancy

SnapMirror

long distance DR data consolidationno limit on distance and usesIP protocol (WAN/LAN)ASync Mirror (> 1 minute)

is used primarily for disaster recovery

SnapVault

disk-to-disk backup, restore HSMno limit on distanceIP protocol (WAN/LAN)ASync Mirror (> 1 hour)

is used primarily for backup/restore

NetApp - Architecture

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