By Dave Simpson
Few disk drive interfaces have generated the buzz that Serial ATA (SATA) is generating. And based on drive shipment predictions, it's easy to understand why.
International Data Corp. analyst Dave Reinsel predicts that shipments of SATA drives for desktops will skyrocket from almost 2.5 million units in 2003 to more than 51 million units this year, topping 124 million units in 2005. In fact, Reinsel predicts that shipments of desktop SATA drives will grow at a 406% CAGR from 2002 through 2007.
Reinsel expects Serial ATA drives to out-ship the predecessor IDE (Parallel ATA) drives in 2005.
SATA's encroachment in the server space will be more measured. Reinsel expects shipments of SATA drives for servers to grow from half a million units last year to two million units this year and 3.6 million units in 2005 (see charts).
Looking out to 2007, Reinsel predicts that there will be an approximate parity in server drive shipments among Fibre Channel, Parallel SCSI, SATA, and Serial-Attached SCSI (SAS).
On the server front, the only debate is whether SATA drives and subsystems are "enterprise" class (e.g., suitable for use in mission-critical server applications), a debate that probably won't be resolved until enough users try out SATA RAID arrays in midrange and high-end application environments.
SATA offers a number of advantages for both end users and storage/systems integrators. For integrators, SATA's cables are longer and thinner than the short, bulky cables required by Parallel ATA, and SATA has a 7-pin connector (versus 40 pins for Parallel ATA), both of which translate into sleeker designss and fewer airflow and heat-design challenges.
For end users, SATA provides "good-enough" storage at a very low cost compared to high-end SCSI and Fibre Channel drives/arrays. The first generation of SATA runs at a 150MBps data rate, and second (300MBps) and third (600MBps) generations are on the road map. (For more information about the technical details of SATA, visit the Serial ATA Working Group's site at www.serialata.org.)
Although the buzz around SATA has been going on for a few years, subsystems are only starting to reach the end-user market, with a rapid ramp-up expected throughout the year. The following is just a sampling of some of the product announcements over the last couple of months. (InfoStor will look at the next batch of SATA products in the March issue.)
This quarter, Nexsan—one of the pioneers of disk-to-disk backup—plans to ship the SATAbladeT RAID array, a 1U eight-drive subsystem with hot-swappable SATA drives, redundant hot-swappable power supplies and cooling fans, dual 10/100/1000 Ethernet ports for management, and support for up to 4GB of cache memory. The company claims a sustained RAID-0 read throughput of 260MBps and a sustained RAID-5 read rate of 320MBps. The subsystem will support 5,400rpm and 10,000rpm SATA drives.
At Comdex, LSI Logic Storage Systems demonstrated a line of SATA subsystems based on LSI controllers and Maxtor's MaXLine of SATA drives. LSI positions the arrays as secondary storage devices for mainstream applications such as reference data, fixed content, and disaster-recovery and backup targets, as well as specialized applications such as rich media, seismic processing, and streaming content.
LSI is currently shipping two SATA subsystems. The 2882 delivers 395MBps throughput, supports up to 28TB (up to 112 drives), and four 2Gbps Fibre Channel host connections. The 5884 delivers 780MBps throughput, a maximum of 56TB (up to 224 drives), and eight 2Gbps Fibre Channel host connections. Because LSI sells largely through resellers, pricing was not available.
Based on LSI subsystems, SGI's InfiniteStorage TP9300S and TP9500S SATA arrays are targeted at applications such as rich media, seismic modeling, and geo-spatial applications. Shipments began last month, with pricing for a 1TB entry-level configuration starting at $39,040. A 3.5TB TP9500S is priced at $124,740.
Also at the higher end of the SATA sub-system market, Chaparral Network Storage is shipping a number of RAID arrays in its RIO eXp family, which include fully redundant components (including controllers) and up to eight Fibre Channel host ports. The arrays are also available in JBOD configurations.
A 4TB R3200 configuration (16 250GB, 7,200rpm SATA drives) is priced at $47,500, while the high-end 62TB R3400 (240 250GB SATA drives) has an MSRP of about $430,000. The company claims performance of more than 665MBps on sequential reads.
Chaparral's SATA RAID systems include a number of value-added features, such as the ability to partition arrays into multiple, variable-size disk partitions, and the ability to mix SATA and Fibre Channel drives in the same enclosure for tiered storage. Last month, Chaparral added software that enables SATA storage to appear as a "virtual tape library" for disk-based backup/recovery applications, as well as "hot-zoning" software to move data streams between SATA and Fibre Channel drives.
SATA arrays from vendors such as SGI and Chaparral represent the relatively high-end of the SATA market, but most of the action is in lower-end, lower-cost configurations. For example, Promise Technology last month began shipments of the VTrak 15100 RAID subsystem with pricing starting at $5,399. The 15100 has dual Ultra160 SCSI host interfaces and can be configured with SATA or Parallel ATA disk drives with an optional SATA-to-PATA adapter. Designed for nearline, midrange environments, the 3U, 15-drive subsystem has hot-swap
redundant components and is based on Promise's controllers, which the company claims deliver up to 200MBps and 15,000 I/Os per second in a RAID-5 configuration.
iSCSI + PATA + SATA
Within the next month or two, Promise plans to ship an iSCSI-compatible SATA disk array. The VTrak 15200 has a dual-port iSCSI host interface and, like the 15100, can be configured with up to 15 PATA or SATA drives. The iSCSI interface includes a TCP offload engine (TOE) that the company claims can deliver wire-speed performance over Gigabit Ethernet. Pricing starts at $6,399.
At Comdex, Infortrend launched 2U eight-bay, 2U 12-bay, and 3U 16-bay EonStor SATA RAID subsystems that are available with dual Ultra160 SCSI host interfaces or up to four Fibre Channel host connections. Prices range from $4,095 to $12,295 (excluding disk drives and Fibre Channel transceivers) for a system with four Fibre Channel host connections, 16-drive bays, dual Infortrend RAID controllers with 256MB of SDRAM each, and dual battery backup modules. Infortrend's controllers support up to 1GB of cache and are based on IBM Power PC CPUs.
Last month, RAID Inc. added SATA RAID arrays to its Falcon line of subsystems. The arrays are available in either 2U eight-bay or 2U 12-bay configurations with either dual Fibre Channel or dual Ultra160 SCSI host interfaces, and hot-swappable controllers, power supplies, and cooling modules.
Two other vendors that recently began shipments of SATA RAID arrays are Adjile Systems and Arena Maxtronic. Adjile's RAID/JBOD SATA arrays come in 2U, 3U, or 4U rack-mount or tower configurations with either Ultra160 SCSI or Fibre Channel host connections. Using 250GB SATA drives, a 3U version stores 4TB. Features include a 64-bit Intel processor, hot-swappable components, support for all RAID levels, and up to 512MB of cache memory.
Arena Maxtronic's Sivy SA-8630 SATA disk array includes a 64-bit Intel i80321 RAID processor, 128MB to 1GB of cache, support for all RAID levels or JBOD configurations, dual Ultra320 SCSI host connections, and a transfer rate of up to 320MBps. Pricing for the Adjile and Arena systems was not available.
SATA for backup
One of the key applications for SATA subsystems is disk-based backup (a.k.a. disk-to-disk backup), an area that CMS Products (formerly CMS Peripherals) is targeting with its Velocity series of SATA arrays. The externally bootable, Windows-compatible devices come in capacities ranging from 80GB to 200GB, with pricing starting at $299. CMS positions the SATA subsystems as alternatives to USB 2.0 or FireWire devices, claiming a 3x performance advantage. The backup-and-restore subsystem comes with CMS's BounceBack software. Additional software functionality includes versioning and synchronization.
On the SATA controller front, start-up RAIDCore hopes to steal some market share from established controller vendors such as Adaptec, LSI, Promise Technology, and 3ware. As potential advantages, RAIDCore vice president of marketing Mark Taylor cites performance, price, and some features that may be unique in the SATA controller market.
RAIDCore's software RAID approach is based on its RAID software stack (and Fulcrum Architecture), which runs on the host. The company claims that CPU utilization overhead typically averages only 4% to 6%. With an 8-channel SATA controller, RAIDCore claims performance of 450MBps for sustained reads and 230MBps on RAID-5 writes. With a 16-channel controller, the company claims performance of 850MBps on sustained reads and 280MBps for RAID-5 write operations. Both controllers are in the RC4000 Series family.
The 2U 8-channel and 16-channel SATA controller are priced at $289 and $362, respectively.
Features include independence from host hardware, operating system, and drive interface; support for Windows (Linux is due next month); online capacity expansion and RAID level migration; split mirroring; and support for up to 32 drives and 64-bit 133MHz PCI-X technology. So far, RAIDCore has signed up Bell Microproducts as a reseller/distributor.
Adaptec last month began shipping a bundled SATA configuration (the 2410SA RAID Enclosure Kit) for its resellers that includes Adaptec's 2410SA RAID controller, a 4-bay hot-swappable drive chassis (OEM'd from Supermicro), cables, and management software. The 4-port 2410SA SATA RAID controller is a follow-on to Adaptec's 2-port SATA controller and includes support for RAID 0, 1, 5, 10, and JBOD configurations; online capacity expansion; and online RAID level migration. MSRP is $390.
This month, 3ware began shipments of multi-lane controllers for internal SATA RAID subsystems. The Escalade 8506 controllers are available with backplanes from chassis vendors such as Advanced Industrial Computer, Chenbro Micom, Ci Designs, and others.
The multi-lane boards have a connector system that combines four SATA ports into a single connection on the controller side and a single connector on a backplane, reducing the number of required connectors. As are 3ware's other controllers, the multi-lane controllers are based on the company's StorSwitch architecture, which uses network packet switching technology in a non-blocking switched fabric.
nStor's line of Wahoo SATA RAID controllers are available with Fibre Channel, Ultra320 SCSI, or iSCSI front-end connections and can connect up to 16 SATA disk drives for a total of 4TB of capacity. Other features include up to 1GB of cache, a 600MHz RISC processor, up to 512 LUNs, clustered LUN sharing, read-write and read-only LUN mapping, support for 64-bit 133MHz PCI-X, all RAID levels, and management software.
Next month, Promise Technology is expected to begin shipments of its SATAII150 SX8 controller, which can connect up to eight SATA drives to a PCI-X bus. The controller (or host bus adapter) complies with the Serial ATA II specifications and includes features such as native command queuing and staggered drive spin-up. The controller works with Linux and Windows 2003/XP/2000 platforms. List price is $249.
SATA for NAS
The SATA interface is also expected to be popular in network-attached storage (NAS) appliances. Raidtec, for example, recently released the SNAZ Pro line of SATA-based NAS filers—the SNAZ S4 and S8—which come in 1U or 2U form factors with internal capacities ranging from 320GB to 2.4TB. An LVD SCSI connection is included for integrated tape backup. MSRP for an entry-level 320GB S4 is $3,895; a 640GB S8 is priced at $7,495.
Raidtec's SNAZ S8 can be expanded with LVD SCSI, Fibre Channel, or FC-SATA drive enclosures. The company claims 50MBps+ per channel over single or dual Gigabit Ethernet LAN connections.
Features of the SNAZ OS software include a logical volume manager; snapshot capability; support for NDMP; NAS replication; RAID 0, 1, 10, and 5; dynamic volume expansion; and WORM functionality. Support for iSCSI is optional.