CLARiiON

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CLARiiON CX500

CLARiiON is a mid-range SAN disk array manufactured and sold by EMC Corporation. Occupying the entry-level and mid-range of EMC's SAN disk array product palette, it is complemented by the high-end Symmetrix. It is now in its fourth generation (denoted by model numbers beginning AX4 / CX4).

It supports fibre channel and iSCSI front end connectivity, with a fibre channel back end. Storage is currently FC-SCSI at 2 or 4Gb/s or SATAII at 3Gb/s arbitrated to 2 or 4.

The CLARiiON storage processor also underpins the EMC Celerra NAS device, which is based on the same X-blade architecture as the CLARiiON storage processor.

The first CLARiiON was developed in the early 1990s by Data General Corporation, one of the first minicomputer companies. CLARiiON was an early commercial example of a RAID product and initially sold exclusively as an array with the company's AViiON line of computer systems. Realizing the enormous potential of storage arrays, Data General created a separate CLARiiON division and began selling the product as an OEM offering to its systems competitors. While this somewhat lessened the advantages of AViiON in the marketplace, and was a source of internal corporate friction, it allowed the company to sell higher volumes and popularize the brand. The strategy paid dividends as the company was acquired by EMC in 1999, primarily for the CLARiiON line of products.

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[edit] History

The CLARiiON disk array was started as a skunk works project inside Data General and was one of the first and most successful RAID product families introduced in the history of the computer industry. Ironically, shortly after the project's initial development, Tom West, the protagonist of the Pulitzer Prize winning book The Soul of a New Machine, usurped development of the product and led the company's last notable development effort prior to Data General's sale to EMC in 1999.

Patented in 1994, the CLARiiON disk array had some interesting features that are now standard in the data storage and computing industry. Features mentioned in the patent paperwork included optional hot swapping,[1] guide rails for proper electrical contact, and a method to lock the drives in place once they were secured in the disk enclosure. Other notable features include industry's first dual active controller design, mirrored write cache, full system redundancy and hot repair.[citation needed]

The CLARiiON line was soon extended to contain SCSI disk arrays ranging from 7 to 30 slots. In 1997, Data General's CLARiiON division took the unusual step of adopting an emerging standard — Fibre Channel. The FC5000 array utilized a Fibre Channel Arbitrated Loop connection that doubled the performance of SCSI arrays at that time. It was also the first to use RAID level 5 on Fibre Channel drives.[citation needed]

From there, the CLARiiON range grew into a faster, more expandable midrange storage platform, culminating in the FC5700 under Data General. After EMC's acquisition of Data General, significant development of a new range of CLARiiON arrays took place, resulting in the FC4500 and FC4700.

Within a couple of years, the first CX series of CLARiiONs (CX200, CX400 and CX600) was developed. Subsequent processor and bandwidth upgrades led to a new CX lineup (CX300, CX500, CX700) and a low end SATA based CLARiiON array, the AX100 (now updated to AX150). In 2003, CLARiiON became the industry's first NEBS-certified storage system.

In May 2006, EMC introduced the third generation of CLARiiON, named CX3 UltraScale. The lineup, consisting of the CX3-20, CX3-40 and CX3-80, was the industry's only storage platform to leverage end-to-end 4 Gbit/s (4 billion bits per second) Fibre Channel and PCI-Express technologies. Later in 2007, the line was expanded to include a new entry-level storage system, the CX3-10.

Most newer CLARiiON models run a version of Windows XP Embedded.

[edit] Architecture

The CLARiiON is build on an Intel platform with embedded Windows (in the fourth generation this is 64-bit Windows Storage Server, the third generation used 32-bit Windows XP). The form factor is a half-width 1U or 2U device known as an X-blade, two of which are mounted side by side in the storage processor enclosure. This provides a fully redundant active-active configuration, with both storage processors serving requests and each acting as failover for the other so that initiators see the array as active-passive. An integrated UPS provides security for data in the event of power failure.

Storage is fibre attached, initiators may be fibre or IP attached, the architecture supports both on the same array depending on configuration. Storage is connected via back-end loops with up to 120 drives per loop, the drives are contained in Disk Array Enclosures (DAEs) of 15 drives each.

The operating environment, Flare, resides on the first five disks of the first DAE (bus 0 enclosure 0), which is also supplied by the integrated UPS. In the event of power failure this space is also used to store the contents of the write cache so that all writes are completed on restoration of power.

Management of the CLARiiON is usually through inbuilt Java-based management software called Navisphere.

With the fourth generation UltraFlex series, IO is provided through pluggable modules providing either IP or fibre connectivity, allowing additional back end and front end connections to be added over the life of the array.

Advanced functionality of the CLARiiON is licensed and enabled through software. This includes SAN replication, QoS and snapshots.

[edit] Current product lineup

[edit] AX series

The AX series is considered the entry-level disk array.

Currently, two models are available the AX4 and the AX150. The AX150 supports up to 12 Serial ATA disks with either 250, 500 or 750 GB (1 GB = 109 B) at a throughput of 150 (250 GB disks) or 300 MB/s (500, 750 GB disks) and, optionally, NCQ. Supported RAID levels are RAID 5 (with min. 3 disks) and RAID 1/0 (min. 4 disks). The Fibre Channel connection supports transfer speeds of up to 2 Gbit/s (with both AL and SW configurations), iSCSI is physically limited to max. 1 Gbit/s. The AX150 is available in four configurations which differ in connection and number of controllers.

The AX4 is the successor of the AX150 and can support up to 60 Serial ATA or Serial Attached SCSI disks (with "Expansion Pack"). The base version has only place for 12 disks. Similar to the AX150 it is available in iSCSI or Fibre Channel configurations. Opposed to the AX150 the AX4 supports Fibre Channel transfer speeds of up to 4 Gbit/s.

Model Connection # of controllers speed # of supported disks
AX150 FC 2 2 Gbit/s 12
AX150SC FC 1 2 Gbit/s 12
AX150i iSCSI 2 1 Gbit/s 12
AX150iSC iSCSI 1 1 Gbit/s 12
AX4-5F FC 1 or 2 4 Gbit/s 12 (60 with "Expansion Pack")
AX4-5I iSCSI 1 or 2 1 Gbit/s 12 (60 with "Expansion Pack")

[edit] CX series

The CX series supports both SATA and Fibre Channel disks. Supported RAID levels are 1/0, 0, 1, 3, 5, and 6; the disks can be configured into groups with different RAID levels.

Models of the CX series come in two configurations: Fibre Channel (transfer speeds max. 2 Gbit/s) and iSCSI (max. 1 Gbit/s). The exception is the CX700, which is FC only. The names of the iSCSI models end with an i, e.g. CX500i.

Model Max. FC hosts Max. disk drives Initial capacity Max. capacity (1 TB = 1012 B)
CX300 64 60 365 GB 27 TB
CX500 128 120 4 TB 59 TB
CX700 256 240 4 TB(?) 119 TB

[edit] CX3 series

The CX3 series originally consisted of CX3-20, CX3-40, and CX3-80 models. Later the series was refreshed to include the CX3-10 and the 'i' and 'f' identifiers.

Model Max. FC hosts Max. disk drives Initial capacity Max. capacity (1 TB = 1012 B)
CX3-10 64 60  ??? GB 45 TB
CX3-20 128 120 4 TB 83 TB
CX3-40 128 240 4 TB(?) 173 TB
CX3-80 256 480 4 TB(?) 353 TB

[edit] CX4 UltraFlex series

The CX4 UltraFlex series contains multiple models which differ in the maximum number of disks (SATA or Fibre Channel) and the number of iSCSI and FC connections. The PCI Express connection between the FC interface and the storage processor allows transfer speeds of up to 4 Gbit/s, while iSCSI supports speeds of max. 1 Gbit/s. All current models support RAID 0, 1, 1/0, 3, 5, and 6; as with the CX series, groups with differing RAID levels can be created.

Each CX4 array consists of dual redundant hot-swappable components including storage processors, mirrored cache and battery backup, as well as redundant power supplies. The CX4 series supports Fibre Chanel and iSCSI host connectivity.

Major New Features in the CX4 UltraFlex Series include support for solid state flash drives, 64-bit FLARE Operating Environment and PCI-Express based SLIC I/O cards. The CX4-480 and CX-960 support fibre chanel solid state flash drives introduced by EMC for the Symmetrix DMX-4 in January of 2008. Solid State Flash drives offer a significant performance advantage over mechanical drives and provide a new storage tier which EMC calls Tier-0. The new version of the FLARE operating environment that ships with the CX4 series includes support for the 64-bit Intel Xeon CPUs in the Storage Processors. The CX4 Series is also the first product to use the new PCI Express based SLIC I/O cards. The product agnostic SLIC I/O cards provide more flexibility for future upgrades as new technologies become available, such as 8GBit Fibre Chanel and 10GBit Ethernet/iSCSI.

Model Cache Front-end FC ports Front-end iSCSI ports Back-end ports Max. HA Hosts Max. disk drives Max. capacity Flash Drives
CX4-120 6 GB 4 4 2 128 120 120 TB Yes
CX4-240 8 GB 4 4 4 256 240 231 TB Yes
CX4-480 16 GB 8 4 4 256 480 471 TB Yes
CX4-960 32 GB 8 4 8 512 960 951 TB Yes

[edit] External links

[edit] References

  1. ^ US5,371,743 (PDF version) (1994-12-06) DeYesso; Joseph P. (Walpole, MA), Solomon; Robert C. (Kensington, NH), Todd; Stephen J. (Shrewsbury, MA), Lippitt; Mark C. (Boulder, CO), On-line module replacement in a multiple module data processing system. 
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