NetApp FAS

In computer storage, NetApp filer, known also as NetApp Fabric-Attached Storage (FAS), or NetApp's network attached storage (NAS) device are NetApp's offering in the area of storage systems. A FAS functions in an enterprise-class storage area network (SAN) as well as a networked storage appliance. It can serve storage over a network using file-based protocols such as NFS, CIFS, FTP, TFTP, and HTTP. Filers can also serve data over block-based protocols such as Fibre Channel (FC), Fibre Channel over Ethernet (FCoE) and iSCSI.^[1] NetApp Filers implement their physical storage in large disk arrays.

Most other large storage vendors' filers tend to use commodity computers with an operating system such as Microsoft Windows Storage Server or tuned Linux. NetApp filers use highly customized hardware and the proprietary Data ONTAP operating system, both originally designed by founders David Hitz and James Lau specifically for storage-serving purposes. Data ONTAP is NetApp's internal operating system, specially optimised for storage functions at high and low level, it is booted from FreeBSD as a stand-alone kernel-space module and use some functions of FreeBSD (command interpreter and drivers stack, for example).

All filers have battery-backed NVRAM, which allows them to commit writes to stable storage quickly, without waiting on disks. Early filers connected to external disk enclosures via SCSI, while modern models (as of 2009^[update]) use FC and SAS protocol. The disk enclosures (shelves) support FC hard disk drives, as well as parallel ATA, serial ATA and Serial attached SCSI.

Implementers often organize two filers in a high-availability cluster with a private high-speed link, either Fibre Channel, InfiniBand, or 10G Ethernet. One can additionally group such clusters together under a single namespace when running in the "cluster mode" of the Data ONTAP 8 operating system.

Internal architecture

Most NetApp filers consist of customized computers with Intel or AMD processors using PCI. Each Filer has a proprietary NVRAM adapter to log all writes for performance and to play the data log forward in the event of an unplanned shutdown. One can link two filers together as a cluster, which NetApp (as of 2009) refers to using the less ambiguous term "Active/Active".

Data ONTAP OS

The Data ONTAP operating system implements a single proprietary file-system called WAFL. When used for file storage, Data ONTAP acts as an NFS server and/or a CIFS server,^{[clarification needed]} serving files to both Unix-like clients and to Microsoft Windows clients from the same file systems. This makes it possible for Unix and Windows to share files by the use of three security styles: mixed, ntfs, and unix. Data ONTAP supports user, group, and tree-based quotas (referred to as q-trees) and allows for data segregation and management within volumes. Qtrees with the UNIX security style will preserve the standard Unix permission-bits, the NTFS security style will preserve NT ACLs found in the Windows environment, and the mixed security allows the use of both interchangeably (with minor loss of fidelity). Since 2002, all NetApp FAS systems can also work as SAN storage over "block-based" protocols such as FC, iSCSI and FCoE (since 2007).

Hardware

Each filer model comes with a set configuration of processor, RAM and NVRAM, which users cannot expand after purchase. With the exception of some of the entry point storage controllers, the NetApp filers have at least one PCIe-based slot available for additional network, tape and/or disk connections. In June 2008 NetApp announced the Performance Acceleration Module (or PAM) to optimize the performance of workloads which carry out intensive random reads. This optional card goes into a PCIe slot and provides additional memory (or cache) between the disk and the filer RAM/NVRAM, thus improving performance.

Storage

NetApp supports either SATA, Fibre Channel, or SAS disk drives, which it groups into RAID (Redundant Array of Inexpensive Disks or Redundant Array of Independent Disks) groups of up to 28 (26 data disks plus 2 parity disks). Multiple RAID groups form an "aggregate"; and within aggregates Data ONTAP operating system sets up "flexible volumes" to actually store data that users can access. An alternative is "Traditional volumes" where one or more RAID groups form a single static volume. Flexible volumes offer the advantage that many of them can be created on a single aggregate and resized at any time. Smaller volumes can then share all of the spindles available to the underlying aggregate. Traditional volumes and aggregates can only be expanded, never contracted. However, Traditional volumes can (theoretically) handle slightly higher I/O throughput than flexible volumes (with the same number of spindles), as they do not have to go through an additional viritualisation layer to talk to the underlying disk.

WAFL File System

WAFL, as a robust versioning filesystem, provides snapshots, which allow end-users to see earlier versions of files in the file system. Snapshots appear in a hidden directory: ~snapshot for Windows (CIFS) or .snapshot for Unix (NFS). Up to 255 snapshots can be made of any traditional or flexible volume. Snapshots are read-only, although Data ONTAP 7 provides additional ability to make writable "virtual clones", based at "WAFL snapshots" technique, as "FlexClones".

Data ONTAP implements snapshots by tracking changes to disk-blocks between snapshot operations. It can set up snapshots in seconds because it only needs to take a copy of the root inode in the filesystem. This differs from the snapshots provided by some other storage vendors in which every block of storage has to be copied, which can take many hours.

SnapMirror

Snapshots form the basis for NetApp disk replication technology SnapMirror, which effectively replicates snapshots between two NetApp filers. Later versions of Data ONTAP introduced cascading replication, where one volume could replicate to another and then another etc. NetApp also offers a backup product based around replicating and storing snapshots, called SnapVault. Open Systems SnapVault allows Windows and UNIX hosts to back up data to a NetApp filer and store any filesystem changes in snapshots.

SyncMirror

Data ONTAP also implements an option called "SyncMirror" where all the RAID groups within an aggregate or traditional volume can be duplicated to another set of hard disks, typically at another site via a Fibre Channel link. NetApp provides a "MetroCluster" option, that uses "SyncMirror" to provide a geo-cluster or active/active cluster between two sites up to 100 km apart.

SnapLock

Other product options include "SnapLock" which implements a "Write Once Read Many" functionality on magnetic disks instead of to optical media, so that data cannot be deleted until its retention period has been reached. SnapLock exists in two modes: compliance and enterprise. The compliance mode was designed to assist organizations in implementing a comprehensive archival solution that meets strict regulatory retention requirements such as dictated by the SEC and several healthcare governing bodies. Records and files committed to WORM storage on a SnapLock Compliance volume cannot be altered or deleted before the expiration of their retention period. Moreover, a SnapLock Compliance volume cannot be destroyed until all data have reached the end of their retention period.

SnapLock Enterprise is geared toward assisting organizations that are more self-regulated and want to have greater flexibility in protecting digital assets with WORM-type data storage. Data stored as WORM on a SnapLock Enterprise volume are protected from alteration or modification with one main difference from SnapLock Compliance: as the files being stored are not for strict regulatory compliance, a SnapLock Enterprise volume can be destroyed by an administrator with root privileges on the FAS system containing the SnapLock Enterprise volume, even if the designed retention period has not yet passed. In both modes, the retention period can be extended, but not shortened, as this is incongruous with the concept of immutability. In addition, NetApp SnapLock data volumes are equipped with a tamper-proof compliance clock that is used as a time reference to block forbidden operations on files, even if the system time is tampered with.

PAM / Flash Cache

NetApp Filer can have PAM ( Performance Accelerate Module ) or Flash Cache (PAM II) which can reduce read latencies and allows the filer to support more read intensive work without adding any further disk to the underlying RAID.

SnapManager Suite

NetApp also offers products for taking application-consistent snapshots by coordinating the application and the NetApp Storage Array. These products support Microsoft Exchange, Microsoft SQL Server, Microsoft Sharepoint, Oracle, SAP and VMware ESX Server data. These products form part of the SnapManager suite.

Previous limitations

Prior to the release of ONTAP 8, individual aggregate sizes were limited to a maximum of 2TB for FAS250 models and 16TB for all other models.

The limitation on aggregate size, coupled with increasing density of disk drives, served to limit the performance of the overall system. NetApp, like most storage vendors, increases overall system performance by parallelizing disk writes to many different spindles (disk drives). Large capacity drives, therefore limit the number of spindles that can be added to a single aggregate, and therefore limit the aggregate performance.

Each aggregate also incurs a storage capacity overhead of approximately 7-11%, depending on the disk type. On systems with many aggregates this can result in lost storage capacity.

However, the overhead comes about due to additional block-checksumming on the disk level as well as usual file system overhead, similar to the overhead in file systems like NTFS or EXT3. Block checksumming helps to insure that data errors at the disk drive level do not result in data loss.

Data ONTAP 8.0 supports a new 64bit aggregate format, which increases the size limit of FlexVolume to approximately 100TB (depending on storage platform) and also increases the size limit of aggregates to more than 100 TB on newer models (depending on storage platform) thus restoring the ability to configure large spindle counts to increase performance and storage efficiency. ([1])

Model history

This list may omit some models. Information taken from spec.org, netapp.com and storageperformance.org

Model	Status	Released	CPU	Main memory	NVRAM	Raw capacity	Benchmark	SPECsfs
FASServer 400	Discontinued	Jan 1993	50 MHz Intel i486	? MB	4 MB	14 GB		?
FASServer 450	Discontinued	Jan 1994	50 MHz Intel i486	? MB	4 MB	14 GB		?
FASServer 1300	Discontinued	Jan 1994	50 MHz Intel i486	? MB	4 MB	14 GB		?
FASServer 1400	Discontinued	Jan 1994	50 MHz Intel i486	? MB	4 MB	14 GB		?
FASServer	Discontinued	Jan 1995	50 MHz Intel i486	256 MB	4 MB	? GB		640
F330	Discontinued	Sept 1995	90 MHz Intel Pentium	256 MB	8 MB	117 GB		1310
F220	Discontinued	Feb 1996	75 MHz Intel Pentium	256 MB	8 MB	? GB		754
F540	Discontinued	June 1996	275 MHz DEC Alpha 21064A	256 MB	8 MB	? GB		2230
F210	Discontinued	May 1997	75 MHz Intel Pentium	256 MB	8 MB	? GB		1113
F230	Discontinued	May 1997	90 MHz Intel Pentium	256 MB	8 MB	? GB		1610
F520	Discontinued	May 1997	275 MHz DEC Alpha 21064A	256 MB	8 MB	? GB		2361
F630	Discontinued	June 1997	500 MHz DEC Alpha 21164A	512 MB	32 MB	464 GB		4328
F720	Discontinued	Aug 1998	400 MHz DEC Alpha 21164A	256 MB	8 MB	464 GB		2691
F740	Discontinued	Aug 1998	400 MHz DEC Alpha 21164A	512 MB	32 MB	928 GB		5095
F760	Discontinued	Aug 1998	600 MHz DEC Alpha 21164A	1 GB	32 MB	1.39 TB		7750
F85	Discontinued	Feb 2001		256 MB	64 MB	648 GB
F87	Discontinued	Dec 2001	1.13 GHz Intel P3	256 MB	64 MB	576 GB
F810	Discontinued	Dec 2001	733 MHz Intel P3 Coppermine	512 MB	128 MB	1.5 TB		4967
F820	Discontinued	Dec 2000	733 MHz Intel P3 Coppermine	1 GB	128 MB	3 TB		8350
F825	Discontinued	Aug 2002	733 MHz Intel P3 Coppermine	1 GB	128 MB	3 TB		8062
F840	Discontinued	Aug/Dec? 2000	733 MHz Intel P3 Coppermine	3 GB	128 MB	6 TB		11873
F880	Discontinued	July 2001	Dual 733 MHz Intel P3 Coppermine	3 GB	128 MB	9 TB		17531
FAS920	Discontinued	May 2004	2.0 GHz Intel P4 Xeon	2 GB	256 MB	7 TB		13460
FAS940	Discontinued	Aug 2002	1.8 GHz Intel P4 Xeon	3 GB	256 MB	14 TB		17419
FAS960	Discontinued	Aug 2002	Dual 2.2 GHz Intel P4 Xeon	6 GB	256 MB	28 TB		25135
FAS980	Discontinued	Jan 2004	Dual 2.8 GHz Intel P4 Xeon MP 2 MB L3	8 GB	512 MB	50 TB		36036
FAS250	EOA 11/08	Jan 2004	600 MHz Broadcom BCM1250 dual core MIPS	512 MB	64 MB	4 TB
FAS270	EOA 11/08	Jan 2004	650 MHz Broadcom BCM1250 dual core MIPS	1 GB	128 MB	16 TB		13620*
FAS2020	EOA	June 2007	2.2 GHz Mobile Celeron	1 GB	128 MB	68 TB
FAS2040		Sept 2009	1.66 GHz Intel Xeon	4 GB	512 MB	136 TB
FAS2050		June 2007	2.2 GHz Mobile Celeron	2 GB	256 MB	104 TB		20027*
FAS2220		June 2012	1.73 GHz Dual Core Intel Xeon C3528	6 GB	768 MB	180 TB
FAS2240		November 2011	1.73 GHz Dual Core Intel Xeon C3528	6 GB	768 MB	432 TB		38000
FAS3020	EOA 4/09	May 2005	2.8 GHz Intel Xeon	2 GB	512 MB	84 TB		34089*
FAS3040	EOA 4/09	Feb 2007	Dual 2.4 GHz AMD Opteron 250	4 GB	512 MB	336 TB		60038*
FAS3050	Discontinued	May 2005	Dual 2.8 GHz Intel Xeon	4 GB	512 MB	168 TB		47927*
FAS3070	EOA 4/09	Nov 2006	Dual 1.8 GHz AMD dual core Opteron	8 GB	512 MB	504 TB		85615*
FAS3140	EOA 2/12	June 2008	Single 2.4 GHz AMD Opteron Dual Core 2216	4 GB	512 MB	420 TB	SFS2008	40109*
FAS3160	EOA 2/12		Dual 2.6 GHz AMD Opteron Dual Core 2218	8 GB	2 GB	672 TB	SFS2008	60409*
FAS3170	EOA 2/12	June 2008	Dual 2.6 GHz AMD Opteron Dual Core 2218	16 GB	2 GB	840 TB	SFS97_R1	137306*
FAS3210		Nov 2010	Single 2.3 GHz Intel Xeon(tm) Processor (E5220)	8 GB	2 GB	480 TB	SFS2008	64292
FAS3220		Nov 2012	Single 2.3 GHz Intel Xeon(tm) Quad Processor (L5410)	24 GB	3.2GB	1440 TB	??	??
FAS3240		Nov 2010	Quad 2.33 GHz Intel Xeon(tm) Processor (Harpertown)	16 GB	2 GB	1,200 TB	??	??
FAS3250		Nov 2012	Dual 2.33GHz Intel Xeon(tm) Processor L5410	40 GB	4 GB	2,160 TB	SFS2008	100922
FAS3270		Nov 2010	Dual 3.0 GHz Intel Xeon(tm) Processor (E5240)	32 GB	4 GB	1,920 TB	SFS2008	101183
FAS6030	EOA 6/09	Mar 2006	Dual 2.6 GHz AMD Opteron	32 GB	512 MB	840 TB	SFS97_R1	100295*
FAS6040		Dec 2007	2.6 GHz AMD dual core Opteron	16 GB	512 MB	840 TB
FAS6070	EOA 6/09	Mar 2006	Quad 2.6 GHz AMD Opteron	64 GB	2 GB	1,008 TB		136048*
FAS6080		Dec 2007	4 to 8 2.6 GHz AMD dual core Opteron	64 GB	4 GB	1,176 TB	SFS2008	120011*
FAS6080							SFS97_R1	164408*
FAS6210		Nov 2010	2x 2.27 GHz Intel Xeon(tm) Processor E5520	48 GB	8 GB	2,400 TB
FAS6220		Feb 2013	2x 64-bit 4-core Intel(R) Xeon(R) Processor E5520	96 GB	8 GB	4,800 TB
FAS6240		Nov 2010	2x 2.53 GHz Intel Xeon(tm) Processor E5540	96 GB	8 GB	2,880 TB	SFS2008	190675
FAS6250		Feb 2013	2x 64-bit 4-core	144 GB	8 GB	5,760 TB
FAS6280		Nov 2010	2x 2.93 GHz Intel Xeon(tm) Processor X5670	192 GB	8 GB	2,880 TB
FAS6290		Feb 2013	2x 64-bit 6-core	192 GB	8 GB	5,760 TB
Model	Status	Released	CPU	Main memory	NVRAM	Raw capacity	Benchmark	SPECsfs

EOA = End of Availability

SPECsfs with "*" is clustered result. SPECsfs performed include SPECsfs93, SPECsfs97, SPECsfs97_R1 and SPECsfs2008. Results of different benchmark versions are not comparable.

References

^ Nabrzyski, Jarek; Schopf, Jennifer M.; Węglarz, Jan (2004). Grid Resource Management: State of the Art and Future Trends. Springer. p. 342. ISBN 978-1-4020-7575-9. Retrieved 11 June 2012.

External links

[1] Nabrzyski, Jarek; Schopf, Jennifer M.; Węglarz, Jan (2004). Grid Resource Management: State of the Art and Future Trends. Springer. p. 342. ISBN 978-1-4020-7575-9. Retrieved 11 June 2012.

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