Writing encoded data slices in a dispersed storage network

Patent metadata

Field	Value
Publication number	US-9778987-B2
Application number	US-201414570366-A
Country	US
Kind code	B2
Filing date	Dec 15, 2014
Priority date	Jan 31, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A method for writing a set of encoded data slices to memory of a dispersed storage network (DSN) begins by a processing module identifying an encoded data slice of the set of encoded data slices for a redundant write operation to produce an identified encoded data slice. The method continues with the processing module generating a set of first write requests regarding the set of encoded data slices less the identified encoded data slice and generating a set of second write requests regarding the identified encoded data slice. The method continues with the processing module sending the set of first write requests to storage units of the DSN and sending the set of second write requests to a set of storage units of the DSN, where each storage unit of the set of storage units is sent a corresponding one of the set of second write requests.

First claim

What is claimed is:

1. A method for writing a set of encoded data slices to memory of a dispersed storage network (DSN), wherein the method is executed by one or more processing modules of one or more computing devices of the DSN, the method comprises:
identifying an encoded data slice of the set of encoded data slices for a redundant write operation to produce an identified encoded data slice;
generating a set of first write requests regarding the set of encoded data slices less the identified encoded data slice;
generating a set of second write requests regarding the identified encoded data slice, the set of second write requests including the identified encoded data slice and replications of the identified encoded data slice;
sending the set of first write requests to storage units of the DSN; and
sending the set of second write requests to a set of storage units of the DSN, wherein each storage unit of the set of storage units is sent a corresponding one of the set of second write requests.

2. The method of claim 1 further comprises:
receiving a write response from a storage unit of the set of storage units; and
sending a delete write request to remaining storage units of the set of storage units.

3. The method of claim 1 further comprises:
receiving write responses from at least some storage units of a combined set of storage units that includes the storage units and the set of storage units; and
when a threshold number of write responses have been received, sending a write commit command to each storage unit of the at least some storage units of the combined set of storage units.

4. The method of claim 3 further comprises:
determining whether the at least some storage units of the combined set of storage units include a storage unit of the set of storage units; and
when the at least some storage units of the combined set of storage units includes the storage unit of the set of storage units:
sending the write commit command to the storage unit of the set of storage units; and
sending a rollback command to each remaining storage unit of the set of storage units.

5. The method of claim 3 further comprises:
determining whether the at least some storage units of the combined set of storage units include a storage unit of the set of storage units; and
when the at least some storage units of the combined set of storage units does not include the storage unit of the set of storage units, sending a rollback command to each storage unit of the set of storage units.

6. The method of claim 3 further comprises:
receiving commit responses from the at least some storage units of the combined set of storage units that includes the storage units and the set of storage units; and
when a commit threshold number of the commit responses have been received, sending a write finalize command to each storage unit of the at least some storage units of the combined set of storage units.

7. The method of claim 6 further comprises:
determining whether the at least some storage units of the combined set of storage units that provided the commit responses include a storage unit of the set of storage units; and
when the at least some storage units of the combined set of storage units that provided the commit responses includes the storage unit of the set of storage units:
sending a write finalize command to the storage unit of the set of storage units; and
sending an undo command to each remaining storage unit of the set of storage units.

8. The method of claim 6 further comprises:
determining whether the at least some storage units of the combined set of storage units that provided the commit responses include a storage unit of the set of storage units; and
when the at least some storage units of the combined set of storage units that provided the commit responses does not include the storage unit of the set of storage units, sending an undo command to the set of storage units.

9. The method of claim 1 further comprises:
identifying a second encoded data slice of the set of encoded data slices for the redundant write operation to produce a second identified encoded data slice;
generating the set of first write requests regarding the set of encoded data slices less the identified encoded data slice and the second identified encoded data slice;
generating a set of third write requests regarding the second identified encoded data slice, the set of third write requests including the second identified encoded data slice and replications of the second identified encoded data slice; and
sending the set of third write requests to a second set of storage units of the DSN, wherein each storage unit of the second set of storage units is sent a corresponding one of the set of third write requests.

10. A computer readable memory device comprises:
at least one memory section that stores operational instructions that, when executed by one or more processing modules of one or more computing devices of a dispersed storage network (DSN), causes the one or more computing devices to:
identify an encoded data slice of a set of encoded data slices for a redundant write operation to produce an identified encoded data slice;
generate a set of first write requests regarding the set of encoded data slices less the identified encoded data slice;
generate a set of second write requests regarding the identified encoded data slice, the set of second write requests including the identified encoded data slice and replications of the identified encoded data slice;
send the set of first write requests to storage units of the DSN; and
send the set of second write requests to a set of storage units of the DSN, wherein each storage unit of the set of storage units is sent a corresponding one of the set of second write requests.

11. The computer readable memory device of claim 10 further comprises:
the at least one memory section stores further operational instructions that, when executed by the one or more processing modules, causes the one or more computing devices of the DSN to:
receive a write response from a storage unit of the set of storage units; and
send a delete write request to remaining storage units of the set of storage units.

12. The computer readable memory device of claim 10 further comprises:
the at least one memory section stores further operational instructions that, when executed by the one or more processing modules, causes the one or more computing devices of the DSN to:
receive write responses from at least some storage units of a combined set of storage units that includes the storage units and the set of storage units; and
when a threshold number of write responses have been received, send a write commit command to each storage unit of the at least some storage units of the combined set of storage units.

13. The computer readable memory device of claim 12 further comprises:
the at least one memory section stores further operational instructions that, when executed by the one or more processing modules, causes the one or more computing devices of the DSN to:
determine whether the at least some storage units of the combined set of storage units include a storage unit of the set of storage units; and
when the at least some storage units of the combined set of storage units includes the storage unit of the set of storage units:
send the write commit command to the storage unit of the set of storage units; and
send a rollback command to each remaining storage unit of the set of storage units.

14. The computer readable memory device of claim 12 further comprises:
the at least one memory section

Assignees

• Cleversafe Inc
• IBM

Inventors

• Shirley Jr Thomas Franklin
• Grube Gary W
• Cilfone Bart
• Khadiwala Ravi
• Dhuse Greg
• Cocagne Thomas Darrel
• Storm Michael Colin
• Vedpathak Yogesh Ramesh
• Leggette Wesley
• Resch Jason K
• Baptist Andrew
• Volvovski Ilya

Classifications

• G06F21/6218

  to a system of files or objects, e.g. local or distributed file system or database · CPC title

• G06F2211/1028

  Distributed, i.e. distributed RAID systems with parity · CPC title

• G06F11/1092 Primary

  Rebuilding, e.g. when physically replacing a failing disk · CPC title

• G06F3/06

  Digital input from, or digital output to, record carriers {, e.g. RAID, emulated record carriers or networked record carriers} · CPC title

• H04L67/1097

  for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS] · CPC title