Installation guide

Chapter 2: Connecting SCSI Drives 5
chapter 2
Connecting SCSI Drives
SCSI hard drives function as the recommended
recording media for Pro Tools TDM systems; it is
there that Pro Tools sessions and audio files are
kept.
Although Pro Tools will let you record to your
system drive, this is generally not recom-
mended. Performance for recording and play-
back on system drives is worse than on non-sys-
tem drives, resulting in lower track counts and
fewer plug-ins.
SCSI hard drives offer several advantages over
ATA/IDE drives. First, SCSI drives can be exter-
nal and therefore provide portable audio storage
that is easily moved between systems. Second,
SCSI drives offer slightly better performance
when recording to large numbers of tracks; at-
tempting to record to a large number of audio
tracks with an ATA/IDE drive will result in a
short delay before recording begins.
SCSI Requirements
High-Performance SCSI Drives and
SCSI Host Bus Adapters
To provide full 64-track, 24-bit, 48 kHz perfor-
mance, a Pro Tools TDM system must include at
least two Digidesign-qualified SCSI hard drives
attached to a qualified SCSI HBA host bus
adapter (HBA) card.
For 64-track sessions that have substantial edit
densities (such as one edit every third of a sec-
ond across 64 voices) or large amounts of cross-
fades, up to four SCSI drives may be required, al-
located with 16 tracks per drive and two drives
per SCSI channel.
SCSI drives must provide a data transfer rate of
at least 9 MB per second of sustained through-
put.
Refer to the Digidesign Web site for compatible
hard drives and HBA cards:
www.digidesign.com/compato/
Older Macintosh Computers
Power Macintosh 9500 and 9600 computers
have two SCSI busses: an internal fast SCSI bus
and an external “narrow” SCSI bus. On these
machines, sessions with higher track counts and
high edit density require a SCSI HBA card. For
optimum performance without a SCSI HBA
card, use the internal fast SCSI bus.
For higher track counts on Power Macintosh
9500, 9600, and Beige G3 computers, avoid us-
ing the external narrow SCSI drive.
Pro Tools 24 requires a MIX Farm card (or
the discontinued Pro Tools 24 Expansion
Kit) to support up to 64 tracks.
Software RAID is not supported for audio
drives.
TDM_Install.book Page 5 Saturday, January 13, 2001 9:35 PM