EP0541992B1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Data reconstruction in a storage device array system
Assignee: Fujitsu Ltd
•
Filing: 1992-10-19
•
Granted: 1998-04-29
•
Expires: 2012-10-19
Abstract
Abstract The present invention provides a storage device array system (24) and method for operating a storage device array system that provides for data transfers to and/or from a storage device array (30) during the reconstruction of data contained in a failed storage device (e.g. 32-7) onto a spare storage device (36). One embodiment of the invention provides for data transfers during the reconstruction of data on the spare storage device (36) onto a storage device that is replacing the failed storage device. Another embodiment of the invention allows data, contained in a storage device to or from which data can be written and read but only in a hindered manner, to be reconstructed on a spare storage device (36) using other storage devices (32) in the array (30). In this situation, write operations to the storage device array (30) are conducted in a manner that provides fault tolerance, i.e. the ability to continue the reconstruction process, in the event one of the other storage devices being used to reconstruct the data on the spare storage device (36) cannot provide the necessary data for reconstruction. <IMAGE>
Inventors
- 👤 Joseph Chen
- 👤 Kenneth Lau
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 10:43
CPC Classifications
G; G11; G11C; G11C29/00; G11C29/70; G06; G06F; G06F11/00; G06F11/07; G06F11/08; G06F11/10; G06F11/1076; G06F11/1084; G06F11/1092; G06F11/14; G06F11/1446; G06F11/1456; G06F11/1458; G06F11/1469; G11C29/88
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
393 words
A storage device array system (24) that has
the ability to conduct data transfers with a host (22)
during reconstruction, comprising: a plurality of storage devices (32-0 to 32-7) for
storing groups of data, each group having data units
distributed over said plurality of storage devices,
each group of data being redundantly encoded such that,
in an absence of error, a subset of said plurality of
storage devices is sufficient for transferring the
group of data to said host (22); a spare storage device (36), additional to said
plurality of storage devices, for use in replacing a
first storage device (e.g. 32-7) of said plurality of
storage devices (32-0 to 32-7); wherein a storage device array (30) includes said
plurality of storage devices (32-0 to 32-7) and said
spare storage device (36) so that, from a plurality of
said data groups, at least first and second data units
stored on said first storage device (32-7) are
reconstructed on said spare storage device (36) in a
reconstruction when said first storage device (32-7) is
in a failed but usable state in which data transfers,
including at least a read data transfer to the host,
are still possible but only with difficulty; means (28) for controlling transfers of data
between the host (22) and said storage device array
(30) including: (i) means for determining when said
reconstruction is to be performed; (ii) data reconstruction means for
performing said reconstruction, said first data unit
being reconstructed before said second data unit, and a
reconstruction boundary (RCB) being defined as a
storage location in said first storage device (32-7)
prior to which reconstruction has been accomplished and
after which reconstruction has not been accomplished; (iii) data transfer conducting means for
conducting a transfer of data between the host (22) and
any of said storage devices (32-0 to 32-6) other than
said first storage device, wherein said transfer of
data occurs between reconstruction of said first data
unit and reconstruction of said second data unit; and reconstruction continuation means for proceeding
with said reconstruction in a case when a data transfer
is conducted with respect to a location that follows
the reconstruction boundary and when a second storage
device e.g. (32-6) of said plurality of storage devices
cannot provide necessary data for reconstruction, by
copying data from said first storage device (32-7) to
said spare storage device (36).
Claim 2
Dependent Claim
38 words
A storage device array system, as claimed in
claim 1, wherein said data transfer conducting means
(28) includes means for writing data from the host (22)
to said spare storage device (36) prior to the
reconstruction boundary (RCB).
Claim 3
Dependent Claim
110 words
A storage device array system, as claimed in
claim 1 or 2, wherein, when said first storage device
(32-7) is in said failed but usable state, said first
storage device transfers data with the host system (22)
during a write data transfer between the host system
and said storage device array system (24) via said data
transfer conducting means (28), said data of said write
data transfer being transformed into at least one group
of data, and wherein said data transfer conducting
means writes said group of data to said spare storage
device (36) prior to the reconstruction boundary and to
said first storage device (32-7) after the
reconstruction boundary.
Claim 4
Dependent Claim
120 words
A storage device array system, as claimed in
claim 1 or 2, wherein, when said first storage device
(32-7) is in said failed but usable state, said first
storage device transfers data with the host system (22)
during a read data transfer between said storage device
array system and the host system, with said data
transfer conducting means (28) for conducting said read
data transfer with the host system using a reading
means for reading data from said plurality of storage
devices; wherein said reading means includes following-data-reading
means for reading data following the
reconstruction boundary (RCB) using said first storage
device (32-7) and any of said plurality of storage
devices (32-0 to 32-6) other than said first storage
device.
Claim 5
Dependent Claim
52 words
A storage device array system, as claimed in
claim 4, wherein said reading means includes prior data
reading means for reading data prior to said
reconstruction boundary (RCB) from said spare storage
device (36) and any of said plurality of storage
devices (32-0 to 32-6) other than said first storage
device (32-7).
Claim 6
Dependent Claim
359 words
A storage device array system (24) that has
the ability to conduct data transfers with a host (22)
during reconstruction, comprising: a plurality of storage devices (32-0 to 32-7) for
storing groups of data units, each group having data
units distributed over said plurality of storage
devices, each group of data being redundantly encoded
such that, in an absence of error, a subset of said
plurality of storage devices is sufficient for
transferring the group of data to said host (22); a spare storage device (36), additional to said
plurality of storage devices (32-0 to 32-7), for use in
replacing a first storage device (e.g. 32-7) of said
plurality of storage devices, wherein a storage device
array (30) includes said plurality of storage devices
(32-0 to 32-7) and said spare storage device (36); means for reconstructing a plurality of data units
from said first storage device (32-7) on said spare
storage device (36) when said first storage device (32-7)
is in a failed but usable state in which a read data
transfer and a write data transfer with the host (22)
are still possible but only with difficulty, said
plurality of data units being included in a plurality
of data groups; means (28) for accessing said plurality of data
units on said spare storage device (36) after
reconstruction by said reconstructing means for a host
initiated data transfer request which results in
transferring data corresponding to said plurality of
data groups between the host (22) and the set of all
said storage devices (32-0 to 32-6,36) including said
spare storage device but excluding said first storage
device (32-7), these storage devices (32-0 to 32-6,36)
being arranged to read or write said plurality of data
groups substantially simultaneously when fulfilling
said host initiated data transfer request; and means for transferring data corresponding to said
plurality of data groups between the host and said set
of storage devices (32-0 to 32-6,36) during
reconstruction by said reconstruction means, said
transferring means being arranged to access a data
location in each of said first storage device (32-7)
and said spare storage device (36) when carrying out a
write data transfer from the host.
Claim 7
Independent Claim
372 words
A method for conducting data transfers with a
host (22) during reconstruction in a storage device
array system (24), comprising steps of: providing a plurality of storage devices (32-0 to
32-7) for storing groups of data units, each group
having data units distributed over said plurality of
storage devices, each group of data being redundantly
encoded such that, in an absence of error, a subset of
said plurality of storage devices is sufficient for
transferring the group of data to said host (22); providing a spare storage device (36), additional
to said plurality of storage devices, for use in
replacing a first storage device (e.g. 32-7) of said
plurality of storage devices (32-0 to 32-7), said spare
storage device and said plurality of storage devices
being included in a storage device array (30) ; performing a reconstruction wherein, from a
plurality of said data groups, at least first and
second data units stored on said first storage device
(32-7) are reconstructed on said spare storage device
(36) when said first storage device (32-7) is in a
failed but usable state in which a read data transfer
and a write data transfer with the host (22) are still
possible but only with difficulty; transferring data between the host (22) and said
storage device array (30) by: (i) determining when said reconstruction is
to be performed; (ii) performing said reconstruction,
said first data unit being reconstructed before said
second data unit, and a reconstruction boundary (RCB)
being defined as a storage location in said first
storage device (32-7) prior to which reconstruction has
been accomplished and after which reconstruction has
not been accomplished; and (iii) conducting a transfer of data
between the host (22) and any of said storage devices
(32-0 to 32-6) other than said first storage device
(32-7), after reconstruction of said first data unit
but before reconstruction of said second data unit; and continuing with said reconstruction in a case when
a data transfer is conducted with respect to a location
that follows the reconstruction boundary and when a
second storage device (e.g. 32-6) of said plurality of
storage devices cannot provide necessary data for
reconstruction, by copying data from said first storage
device (32-7) to said spare storage device (36).
Claim 8
Dependent Claim
32 words
A method as claimed in claim 7, wherein said
data transfer conducting step includes writing data
from the host (22) to said spare storage device (36)
prior to the reconstruction boundary (RCB).
Claim 9
Dependent Claim
109 words
A method as claimed in claim 7 or 8, wherein: when said first storage device (32-7) is in said
failed but usable state, said first storage device
transfers data with the host system (22) during a write
data transfer between the host system and said storage
device array system (24), said data transfer conducting
step including conducting said write data transfer with
the host system by transforming data of said write data
transfer into at least one group of data, and writing
said group of data to said spare storage device (36)
prior to the reconstruction boundary (RCB) and to said
first storage device (32-7) after the reconstruction
boundary.
Claim 10
Dependent Claim
95 words
A method as claimed in claim 7 or 8 wherein, when said first storage device (32-7) is in said
failed but usable state, said first storage device
transfers data with the host system (22) during a read
data transfer between said storage device array system
and the host system, said data transfer conducting step
comprising conducting said read data transfer with the
host system by reading data following the reconstruction
boundary (RCB) using said first storage device (32-7)
and any of said plurality of storage devices (32-0 to
32-6) other than said first storage device.
Claim 11
Dependent Claim
44 words
A method as claimed in claim 10 wherein; said reading step includes reading data prior to
said reconstruction boundary (RCB) from said spare
storage device (36) and any of said plurality of
storage devices (32-0 to 32-6) other than said first
storage device (32-7).
Claim 12
Independent Claim
341 words
A method for conducting data transfers with a
host (22) during reconstruction in a storage device
array system, comprising: providing a plurality of storage devices (32-0 to
32-7) for storing groups of data units, each group
having data units distributed over said plurality of
storage devices, each group of data being redundantly
encoded such that, in an absence of error, a subset of
said plurality of storage devices is sufficient for
transferring the group of data to said host (22); providing a spare storage device (36), additional
to said plurality of storage devices, for use in
replacing a first storage device (e.g. 32-7) of said
plurality of storage devices, wherein a storage device
array (30) includes said plurality of storage devices
(32-0 to 32-7) and said spare storage device (36); reconstructing a plurality of data units from said
first storage device (32-7) on said spare storage
device (36) when said first storage device is in a
failed but usable state in which a read data transfer
and a write data transfer with the host are still
possible but only with difficulty, said plurality of
data units being included in a plurality of data
groups; accessing said plurality of data units on said
spare storage device (36) after said step of
reconstructing for a host initiated data transfer
request which results in transferring data, corresponding to said plurality of data groups, between
the host and the set of all said storage devices (32-0
to 32-6,36) including said spare storage device but
excluding said first storage device (32-7), these
storage devices reading or writing said plurality of
data groups substantially simultaneously when
fulfilling said host initiated data transfer request;
and transferring data corresponding to said plurality
of data groups between the host (22) and said set of
storage devices (32-0 to 32-6,36) during said step of
reconstructing; wherein a data location in each of said first
storage device (32-7) and said spare storage device
(36) is accessed when said step of transferring
includes a write to said storage device array from the
host.
References Cited (Backward Citations)
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