Difference between revisions of "SCSI hard disk replacement options"

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(Minor, but previous one marked minor ended up being major. Added SCSI RAID, more tidying.)
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Most classic macs use a hard disk drive as their main mass storage medium. The majority of 68k Macs uses SCSI hard disk drives of a kind not in production any more. There are several options to replace a defective SCSI hard disk drive. Here you will find some suggestions.
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==Introduction==
 +
Most classic macs use a hard disk drive (HDD or HD) as their boot device and main mass storage medium. The majority use SCSI drives of a kind no longer in production; either 50 pin 3.5" desktop drives, or the exceptionally rare 2.5" laptop SCSI drives.  
  
The choice should depend on the use to be expected for the device.  
+
There are several replacement options for defective SCSI drives.  Even with a working SCSI boot drive, a second drive for extra storage is often desirable.
  
--
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The choice depends on the expected use of the device, and the performance required.  Note that the throughput of a faster, more modern drive is usually throttled by the slow SCSI speed on the Mac itself.    Unless you are using a high-performance  [[Upgrades/Drive controllers|drive controller]], it will still be limited to the host Mac's speed
  
*For frequent use with heavy writing load, where write access performance is important, try a [[SCSI-IDE converter]] with a new silent [[IDE]] harddisk (2.5" or 3.5"). Keep in mind that the throughput of a modern drive is usually throttled by the slow host adaptor or bus speed, not the drive itself.
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==Options==
  
*If you need very low noise, or low heat (as in a fanless Mac), but with top performance, try a Solid State Disk ([[SSD]]) or industrial Compact Flash ([[CF]]) card and adaptor.  Some CF adapters mount two cards, however the IDE bus in the Mac may not recognise two separate cards.
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Choices may be classified by
  
*A striped [[RAID]] can provide even faster performance.  Unless you are using a high-performance  [[Upgrades/Drive controllers|drive controller]], it will still be limited to the host Mac's speed
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:Storage medium
 +
:Adapter(s) required
 +
:Use, or
 +
:Performance
  
*Find Information about solid state disks in the article [http://68kmla.net/wiki/Using_flash_memory using flash memory].
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===SCSI===
  
*In any other case a recent CF card in an appropriate adaptor should do well in a vintage machine. (Use for [[virtual memory]] is [http://68kmla.net/forums/viewtopic.php?p=64733#64733| debated])
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*3.5" SCSI drives are still available, but rarely with the native 50 pin interface of older Macs. An [[SCSI Pin Converter|adapter]] from 68 or 80 pin to 50 pin, or a [[Upgrades/Drive controllers|SCSI card]] is required. These are usually server drives: they can be noisy, but offer relatively large capacities, high performance and reliability.
  
*A [[MicroDrive]] would give you the benefits of a small footprint, low power consumption and fast write speeds. It would combine the alleged disadvantages of both CF cards (see above) and usual hard disk drives (ie moving parts).
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*External SCSI enclosures are available for single drives, pairs, and multiples of 7, 14 and so on.  With a long enough cable, the enclosure can be hidden in a place where noise can be contained. Some host 68 or 80 pin drives internally, yet interface to the host with a 50 pin cable.  Even if not, a single 50 pin to 68 or 80 pin SCSI adaptor to a multi-bay enclosure could be more economical than buying adapters for individual drives.  Drives too small for practical single use can be combined. You gain a cheap supply for high speed drives. This especially applies to people with access to server farms, where drives are regularly swapped out for new ones.
   
 
*If price matters, consider an external SCSI enclosure filled up with used SCSI server hard disks. With a long cable you can hide the drive in a place where the noise can be contained. Some host 68 or 80 pin drives internally, yet interface to the host with a 50 pin cable.  Even if not, a single 50 pin to 68 or 80 pin SCSI adaptor should allow you to connect to a Mac much more economically than buying adapters for individual drives. You gain a cheap supply for high speed drives. This especially applies to people with access to server farms, where usable drives get swapped for new ones based on a fixed schedule.
 
  
 
*A SCSI RAID array would be a very flexible, high performance, and relatively expensive external solution.  Typically used with servers, these boxes have an intelligent RAID controller onboard, and interface to the host via a single cable.  Other advantages are as described in the above entry on SCSI external boxes.  
 
*A SCSI RAID array would be a very flexible, high performance, and relatively expensive external solution.  Typically used with servers, these boxes have an intelligent RAID controller onboard, and interface to the host via a single cable.  Other advantages are as described in the above entry on SCSI external boxes.  
 +
 +
===IDE and Flash===
 +
 +
*For frequent use with heavy writing load, where write speed is important, try a [[SCSI-IDE converter]] with a new silent [[IDE]] harddisk (2.5" or 3.5").  IDE drives are the cheapest option in very large capacities, and may offset the cost of the converter.
 +
 +
*If you need very low noise, or low heat (as in a fanless Mac), but with top performance and guaranteed reliability, try a Solid State Disk ([[SSD]]) or industrial-grade Compact Flash ([[CF]]) card and adaptor.  This comes at a cost compared to consumer flash devices.  <ref name="2cf">Some CF adapters mount two cards; it remains to be seen if both will be recognised in a SCSI Mac.</ref>
 +
 +
*A recent consumer CF card in an appropriate adapter<ref name="2cf" /> should do well in a vintage machine. (Use for [[virtual memory]] is [http://68kmla.net/forums/viewtopic.php?p=64733#64733| debated])
 +
 +
*A [[MicroDrive]] would give you the benefits of a small footprint, low power consumption, noise and heat, and fast write speeds.  While not as robust against physical damage as Flash devices (ie it still has moving parts), it has none of the write-cycle limitations of consumer-grade Flash.
 +
 +
*A striped [[RAID]] can provide even faster performance.
 +
 +
===Other===
 +
 +
*[[Network Attached Storage]] (NAS) devices provide a [[LAN]] interface to a hard disk, typically IDE/ATA or SATA.  If your Mac has Ethernet and a working boot disk this is an option for extra storage.  In some cases, this may be as fast or faster than a local SCSI disk.  Used IDE NAS devices can be picked up fairly cheaply.
 +
 +
*SCSI-mounted card readers for PCMCIA (PC Card), CF, or other storage devices are under investigation, with some success reported.
  
 
*And, a more hypothetical case, if the price should not matter at all, have an UPS buffered RAM-disk and stream the data to a NAS.
 
*And, a more hypothetical case, if the price should not matter at all, have an UPS buffered RAM-disk and stream the data to a NAS.
  
Always have a working backup of your important data!
+
==See Also:==
 
 
==Hints==
 
  
 
If you are interested in a solid state storage solution, go to the page about [http://68kmla.net/wiki/Using_flash_memory using flash memory].
 
If you are interested in a solid state storage solution, go to the page about [http://68kmla.net/wiki/Using_flash_memory using flash memory].
  
 
If want to use an IDE drive, go to the page about [http://68kmla.net/wiki/SCSI-IDE_converter SCSI-IDE converter].
 
If want to use an IDE drive, go to the page about [http://68kmla.net/wiki/SCSI-IDE_converter SCSI-IDE converter].
 +
 +
==Notes==
 +
Always have a working backup of your important data!
 +
{{reflist}}
  
 
[[Category:Tutorials]]
 
[[Category:Tutorials]]
 
[[Category:Essays]]
 
[[Category:Essays]]
 
[[Category:Storage devices]]
 
[[Category:Storage devices]]

Revision as of 01:06, 27 July 2008

Stop icon color.pngThis article may require cleanup to meet 68kMLA's quality standards.

Introduction

Most classic macs use a hard disk drive (HDD or HD) as their boot device and main mass storage medium. The majority use SCSI drives of a kind no longer in production; either 50 pin 3.5" desktop drives, or the exceptionally rare 2.5" laptop SCSI drives.

There are several replacement options for defective SCSI drives. Even with a working SCSI boot drive, a second drive for extra storage is often desirable.

The choice depends on the expected use of the device, and the performance required. Note that the throughput of a faster, more modern drive is usually throttled by the slow SCSI speed on the Mac itself. Unless you are using a high-performance drive controller, it will still be limited to the host Mac's speed

Options

Choices may be classified by

Storage medium
Adapter(s) required
Use, or
Performance

SCSI

  • 3.5" SCSI drives are still available, but rarely with the native 50 pin interface of older Macs. An adapter from 68 or 80 pin to 50 pin, or a SCSI card is required. These are usually server drives: they can be noisy, but offer relatively large capacities, high performance and reliability.
  • External SCSI enclosures are available for single drives, pairs, and multiples of 7, 14 and so on. With a long enough cable, the enclosure can be hidden in a place where noise can be contained. Some host 68 or 80 pin drives internally, yet interface to the host with a 50 pin cable. Even if not, a single 50 pin to 68 or 80 pin SCSI adaptor to a multi-bay enclosure could be more economical than buying adapters for individual drives. Drives too small for practical single use can be combined. You gain a cheap supply for high speed drives. This especially applies to people with access to server farms, where drives are regularly swapped out for new ones.
  • A SCSI RAID array would be a very flexible, high performance, and relatively expensive external solution. Typically used with servers, these boxes have an intelligent RAID controller onboard, and interface to the host via a single cable. Other advantages are as described in the above entry on SCSI external boxes.

IDE and Flash

  • For frequent use with heavy writing load, where write speed is important, try a SCSI-IDE converter with a new silent IDE harddisk (2.5" or 3.5"). IDE drives are the cheapest option in very large capacities, and may offset the cost of the converter.
  • If you need very low noise, or low heat (as in a fanless Mac), but with top performance and guaranteed reliability, try a Solid State Disk (SSD) or industrial-grade Compact Flash (CF) card and adaptor. This comes at a cost compared to consumer flash devices. [1]
  • A recent consumer CF card in an appropriate adapter[1] should do well in a vintage machine. (Use for virtual memory is debated)
  • A MicroDrive would give you the benefits of a small footprint, low power consumption, noise and heat, and fast write speeds. While not as robust against physical damage as Flash devices (ie it still has moving parts), it has none of the write-cycle limitations of consumer-grade Flash.
  • A striped RAID can provide even faster performance.

Other

  • Network Attached Storage (NAS) devices provide a LAN interface to a hard disk, typically IDE/ATA or SATA. If your Mac has Ethernet and a working boot disk this is an option for extra storage. In some cases, this may be as fast or faster than a local SCSI disk. Used IDE NAS devices can be picked up fairly cheaply.
  • SCSI-mounted card readers for PCMCIA (PC Card), CF, or other storage devices are under investigation, with some success reported.
  • And, a more hypothetical case, if the price should not matter at all, have an UPS buffered RAM-disk and stream the data to a NAS.

See Also:

If you are interested in a solid state storage solution, go to the page about using flash memory.

If want to use an IDE drive, go to the page about SCSI-IDE converter.

Notes

Always have a working backup of your important data!

  1. 1.0 1.1 Some CF adapters mount two cards; it remains to be seen if both will be recognised in a SCSI Mac.