Browse Prior Art Database

Tape Array Storage System

IP.com Disclosure Number: IPCOM000104171D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 87K

Publishing Venue

IBM

Related People

Ouchi, NK: AUTHOR

Abstract

Disclosed is a tape storage system that provides access to tape data where one or more tape cartridges are not available. Data are stored on multiple cartridges that are managed as single unit by the library or system control. Ouchi taught that data can be recovered from failed storage units by storing the data in two or more failure independent storage units and adding redundant data to recover from the loss of one unit [*]. This disclosure teaches that the failure independent units may be tape cartridges or other removable media. Fig. 1 illustrates a tape control with multiple tape drives. The control has stripping storage the logic to divide the data into segments, generate the necessary redundant segments to recover from the loss of one or more cartridges and spread the segmented across the tape drives.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Tape Array Storage System

      Disclosed is a tape storage system that provides access to tape
data where one or more tape cartridges are not available.  Data are
stored on multiple cartridges that are managed as single unit by the
library or system control.  Ouchi taught that data can be recovered
from failed storage units by storing the data in two or more failure
independent storage units and adding redundant data to recover from
the loss of one unit [*].  This disclosure teaches that the failure
independent units may be tape cartridges or other removable media.
Fig. 1 illustrates a tape control with multiple tape drives.  The
control has stripping storage the logic to divide the data into
segments, generate the necessary redundant segments to recover from
the loss of one or more cartridges and spread the segmented across
the tape drives.  The cartridges are managed as though they were as
single unit.  Data are read back using the same mechanism with error
correction to recover data that may have been lost due to cartridge
errors or loss.

      Also disclosed:  Multiple addressable domains - several data
sets or addressable groups of data may be stored on the same set of
cartridges.

      Each cartridge is self identifying so that the cartridges may
be inserted in any operational drive.  Each cartridge has a header
record that identifies the other cartridges and the sequence in which
they must be read to reconstruct the data.  The tape drive system may
read/write cartridges in the normal method for cartridges not used in
an array.

      The cartridges may support multiple domain widths.  Each
addressable domain can have different number of data and parity
cartridges.  For example with ten cartridges: a domain can be 8 data
with one parity, another domain can be two groups of 4 data and with
parity each, another domain can be 8 data with parity and an RS
double error correcting code, Q. The cartridges are self descriptive
so that the control can accept any of the supported configurations.

      The tape control can support multiple domains with differing
numbers of cartridges.  For example, a cartridge set may be nine
cartridges for 8 data plus parity; another may be five cartridges for
4 plus parity; another...