Distributed storage time synchronization based on storage delay

Patent metadata

Field	Value
Publication number	US-9344500-B2
Application number	US-201414319282-A
Country	US
Kind code	B2
Filing date	Jun 30, 2014
Priority date	Dec 29, 2009
Publication date	May 17, 2016
Grant date	May 17, 2016

Abstract

A method begins with a processing module receiving a data retrieval request and obtaining a real-time indicator corresponding to when the data retrieval request was received. The method continues with the processing module determining a time-based data access policy based on the data retrieval request and the real-time indicator and accessing a plurality of dispersed storage (DS) units in accordance with the time-based data access policy to retrieve encoded data slices. The method continues with the processing module decoding the threshold number of encoded data slices in accordance with an error coding dispersal storage function when a threshold number of the encoded data slices have been retrieved.

First claim

What is claimed is:

1. A method for synchronizing availability of data slices for retrieval from distributed storage units based on storage transmission delays, comprising:
determining transmission time delays between a processing unit, having a processor, and a plurality of distributed storage units communicating with the processing unit, in which the plurality of distributed storage units are configured to receive and store n number of encoded data slices of a data segment by having a respective distributed storage unit store a respective one of the n encoded data slices of the data segment and in which at least a threshold number k of the n encoded data slices are needed to reconstruct the data segment, where k is less than n;
selecting a set of distributed storage units based on the transmission time delays;
determining a longest transmission time delay from respective transmission time delays for the selected set of distributed storage units;
determining corresponding additional time delay value to add to the respective transmission time delays for the selected set of distributed storage units, in order to synchronize total delay between the processing unit and respective ones of the selected set of distributed storage units to substantially coincide with the longest transmission time delay; and
transmitting n encoded data slices from the processing unit to the plurality of distributed storage units, along with corresponding additional time delay values to the selected set of distributed storage units, in which the corresponding additional time delay values are to be utilized at the selected set of distributed storage units to delay access to received encoded data slices at the selected set of distributed storage units for an additional time period determined by the corresponding additional time delay value.

2. The method of claim 1 , wherein when selecting the set of distributed storage units, all of the plurality of distributed storage units are selected as the selected set of distributed storage units.

3. The method of claim 1 , wherein when selecting the set of distributed storage units, a subset of the plurality of distributed storage units is selected as the selected set of distributed storage units.

4. The method of claim 1 , wherein when selecting the set of distributed storage units, a subset of the plurality of distributed storage units is selected as the selected set of distributed storage units and the subset is selected based on shortest transmission time delays.

5. The method of claim 1 , wherein when selecting the set of distributed storage units, k number of distributed storage units are selected as the selected set of distributed storage units.

6. The method of claim 1 , wherein when selecting the set of distributed storage units, k number of distributed storage units are selected as the selected set of distributed storage units and the k number of distributed storage units are selected based on shortest transmission time delays.

7. The method of claim 1 , wherein when transmitting the n encoded data slices, a timer is to be used at the selected set of distributed storage units to prevent access to the received encoded data slices, in which the timer commences upon receiving the encoded slices and expires based on the corresponding additional time delay value and in which corresponding access for encoded data slice retrieval is granted upon expiration of the timer for respective ones of the selected set of distributed storage units.

8. A method for synchronizing availability of data slices for retrieval from distributed storage units based on storage transmission delays, comprising:
determining transmission time delays between a processing unit, having a processor, and a plurality of distributed storage units communicating with the processing unit, in which the plurality of distributed storage units are configured to receive and store n number of encoded data slices of a data segment by having a respective distributed storage unit store a respective one of the n encoded data slices of the data segment and in which at least a threshold number k of the n encoded data slices are needed to reconstruct the data segment, where k is less than n;
selecting a set of distributed storage units based on the transmission time delays;
determining a longest transmission time delay from respective transmission time delays for the selected set of distributed storage units;
determining corresponding additional time delay value to add to the respective transmission time delays for the selected set of distributed storage units, in order to synchronize total delay between the processing unit and respective ones of the selected set of distributed storage units to substantially coincide with the longest transmission time delay; and
transmitting n encoded data slices from the processing unit to the plurality of distributed storage units, but in which the processor delays transmitting respective encoded data slices to the selected set of distributed storage units by a time period determined by the corresponding additional time delay values to synchronize arrival of the respective encoded data slices to the selected set of distributed storage units.

9. The method of claim 8 , wherein when selecting the set of distributed storage units, all of the plurality of distributed storage units are selected as the selected set of distributed storage units.

10. The method of claim 8 , wherein when selecting the set of distributed storage units, a subset of the plurality of distributed storage units is selected as the selected set of distributed storage units.

11. The method of claim 8 , wherein when selecting the set of distributed storage units, a subset of the plurality of distributed storage units is selected as the selected set of distributed storage units and the subset is selected based on shortest transmission time delays.

12. The method of claim 8 , wherein when selecting the set of distributed storage units, k number of distributed storage units are selected as the selected set of distributed storage units.

13. The method of claim 8 , wherein when selecting the set of distributed storage units, k number of distributed storage units are selected as the selected set of distributed storage units and the k number of distributed storage units are selected based on shortest transmission time delays.

14. The method of claim 8 , further comprising utilizing a timer, in which the processor uses the timer to delay transmitting respective encoded data slices to the selected set of distributed storage units.

15. A method for synchronizing availability of data slices for retrieval from distributed storage units based on storage transmission delays, comprising:
determining a first set of transmission time delays between a first processing unit, having a first processor, and a plurality of distributed storage units communicating with the first processing unit, in which the plurality of distributed storage units are configured to receive and store first n number of encoded data slices of a first data segment from the first processing unit by having a respective distributed storage unit store a respective one of the first n encoded data slices of the first data segment and in which at least a threshold number k of the first n encoded data slices are needed to reconstruct the first data segment, where k is less than n;
communicating between the first processing unit and a second processing unit, which has a second processor, to receive at the first processing unit a second set of transmission time delays from the second processing unit, in which t

Assignees

• Cleversafe Inc
• IBM

Inventors

• Resch Jason K
• Grube Gary W
• Markison Timothy W

Classifications

• G06F11/1076 Primary

  Parity data used in redundant arrays of independent storages, e.g. in RAID systems · CPC title

• H04L63/108

  when the policy decisions are valid for a limited amount of time · CPC title

• G06F21/62

  Protecting access to data via a platform, e.g. using keys or access control rules · CPC title

• G06F2211/1028

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

• H04L67/1097 Primary

  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