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Highpoint HPT370 ATA/100 RAID Controller Chip
Last updated: 7/27/00

This 144-pin chip is starting to show-up on motherboards and ATA/100 controller expansion boards.  What it does is what the motherboard chipsets don't do yet.  It brings ATA/100 performance and a couple of extra IDE interfaces to motherboards, and RAID features to IDE hard disk drives.  So, I thought this little gem deserved its own little article...

What is ATA/100?  Ultra ATA/100 is an updated version of the ATA/66 disk drive data bus introduced by Quantum in 1998.  The ATA/100 specification defines a physical layer operating at 100 megabytes per second (MBs).  It is backward compatible with ATA/33 and ATA/66 enabled devices; i.e., ATA/33 and ATA/66 drives can be connected to an ATA/100 interface.  ATA/100 drives use the same  80-conductor, 40-pin cable introduced for by ATA/66 standard.  If an older, 40-pin IDE cable is connected to an ATA/100 (or ATA/66) interface, it will work; however, the drive will be treated as an ATA/33 drive or, if older, whatever the drive actually is.

What is RAID?  A RAID or Redundant Array of Inexpensive Disks is a collection of disk drives that collectively act as a single storage system. In other words, two or more hard disk drives which are grouped together and appear as a single disk drive.  Or, in practice, it can also be two or more disk partitions grouped together and appear as a single partition/logical drive.  A partition or volume is just that, a demarcated and contiguous section of a drive which appears like a drive--a logical drive.  There are six levels of RAID and the features of more than one level can combined in a RAID.  The HPT370 supports three flavors of RAID:

  • Stripping (RAID Level 0).   Provides performance (not redundant as implied in the acronym).  Data is evenly spread over identical drives.  That is, parts of file can be spread over more than one drive.  Data can be read and written in parallel.    Performance is very good.  Failure of any one disk in the array results in data loss.  This kind of RAID would be good for storing large files of temporary nature, but you sure wouldn't want to put you accounting package on one.

  • Mirroring (RAID level 1).   Provides redundancy.  Two drives duplicate each other identicallyIf one drive fails, all of the data is available on the other one.  The read performance of mirrored drives can be increased through load balancing and elevator sorting (I won't go into elevator sorting here).  Simply put, when data is requested it is read from the least busy drive.  Put that accounting package on this one; I did.  But remember it is possible for Windows to "scribble" on a hard disk.  In this arrangement, a scribble on one drive is more than likely a "scribble" on both drives--mirrored garbage is garbage.

  • Striping/Mirroring (RAID 0+1).  Provides performance and redundancy.  Two sets of stripped drives (four drives in the case of the HP370) are mirrored.  This arrangement may be fast and redundant, but it is also expensive and complicated.

RAID can be done with software as well as hardware.  The configuration of our Windows NT file server is similar to RAID 1.  A critical partition on the primary drive is mirrored to a like partition on the secondary drive. We also did it quite a few years ago with two 340 MByte IDE hard disks and another IDE controller in a Novell file server with a 386 motherboard. SCSI drives have been used in mirrored configurations for many years.  Putting the IDE RAID function/chip on the motherboard is new.

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