Processing data access requests in accordance with a storage unit memory pressure level

Patent metadata

Field	Value
Publication number	US-11029880-B2
Application number	US-201916290503-A
Country	US
Kind code	B2
Filing date	Mar 1, 2019
Priority date	Mar 1, 2019
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A method includes determining, by a storage unit of a dispersed storage network (DSN), a storage unit memory pressure level. When the storage unit memory pressure level compares unfavorably to a threshold, the method further includes, in response to a data access request regarding an encoded data slice from a computing device, determining whether the data access request includes an override message or a non-override message. When the data access request includes the non-override message, the method includes generating a storage unit memory pressure level message in accordance with the storage unit memory pressure level and the type of data access request, sending the storage unit memory pressure level message to the computing device, and processing the data access request in accordance with the storage unit memory pressure level message. When the data access request includes the override message, the method further includes processing the data access request.

First claim

What is claimed is:

1. A method comprises:
determining, by a storage unit of a dispersed storage network (DSN), a storage unit memory pressure level based on a number of different versions of an encoded data slice of a set of encoded data slices currently stored in a proposal record of the encoded data slice and memory capacity of the storage unit, wherein the proposal record includes an ordered list of pending transactions for the encoded data slice and an ordered list of different versions of the encoded data slice; and
when the storage unit memory pressure level indicates that the storage units are storing more active contests than a threshold:
in response to a data access request regarding the encoded data slice from a computing device of the DSN, determining whether the data access request includes an override message or a non-override message;
when the data access request includes the non-override message:

generating, by the storage unit, a storage unit memory pressure level message in accordance with the storage unit memory pressure level and a type of data access request;
sending, by the storage unit, the storage unit memory pressure level message to the computing device; and
processing, by the storage unit, the data access request in accordance with the storage unit memory pressure level message; and
when the data access request includes the override message:
processing, by the storage unit, the data access request.

2. The method of claim 1 , wherein generating the storage unit memory pressure level message further comprises:
when the data access request includes one or more of: one or more write requests and one or more write commit requests:
determining, by the storage unit, a severity level of the storage unit memory pressure level; and
generating, by the storage unit, the storage unit memory pressure level message based on the severity level to include one or more of:
an error message;
a warning message;
a rejection of the data access request
an indication of the storage unit memory pressure level;
a request to adjust data access request sending rate;
a request to resend the data access request after a time period; and
an estimated time period for the storage unit memory pressure level.

3. The method of claim 1 , wherein generating the storage unit memory pressure level message further comprises:
when the data access request includes one or more of: one or more close-out requests and one or more no-contest requests;
generating, by the storage unit, the storage unit memory pressure level message to indicate that the data access request is allowed and to include one or more of:
an indication of the storage unit memory pressure level; and
an estimated time period for the storage unit memory pressure level.

4. The method of claim 3 , wherein the one or more close-out requests include:
one or more write finalize requests; and
one or more cleanup requests.

5. The method of claim 3 , wherein the one or more no-contest requests include:
one or more read requests;
one or more delete requests;
one or more list requests; and
one or more edit requests.

6. The method of claim 1 , wherein the data access request includes a slice name for the encoded data slice, a transaction number, a type of request, and a current revision level of the encoded data slice.

7. A storage unit of a dispersed storage network (DSN), the storage unit comprises:
an interface;
memory; and
a processing module operably coupled to the memory and the interface, wherein the processing module is operable to:
determine a storage unit memory pressure level based on a number of different versions of an encoded data slice of a set of encoded data slices currently stored in a proposal record of the encoded data slice and memory capacity of the storage unit, wherein the proposal record includes an ordered list of pending transactions for the encoded data slice and an ordered list of different versions of the encoded data slice; and
when the storage unit memory pressure level indicates that the storage unit is storing more active contests than a threshold:
in response to a data access request regarding the encoded data slice from a computing device of the DSN, determining whether the data access request includes an override message or a non-override message;
when the data access request includes the non-override message:
generating, by the storage unit, a storage unit memory pressure level message in accordance with the storage unit memory pressure level and a type of data access request;
sending, by the storage unit, the storage unit memory pressure level message to the computing device; and
processing, by the storage unit, the data access request in accordance with the storage unit memory pressure level message; and

when the data access request includes the override message:

processing, by the storage unit, the data access request.

8. The storage unit of claim 7 , wherein the processing module is further operable to generate the storage unit memory pressure level message by:
when the data access request includes one or more of: one or more write requests and one or more write commit requests:
determining a severity level of the storage unit memory pressure level; and
generating the storage unit memory pressure level message based on the severity level to include one or more of:
an error message;
a warning message;
a rejection of the data access request
an indication of the storage unit memory pressure level;
a request to adjust data access request sending rate;
a request to resend the data access request after a time period; and
an estimated time period for the storage unit memory pressure level.

9. The storage unit of claim 7 , wherein the processing module is further operable to generate the storage unit memory pressure level message by:
when the data access request includes one or more of: one or more close-out requests and one or more no-contest requests;
generating the storage unit memory pressure level message to indicate that the data access request is allowed and to include one or more of:
an indication of the storage unit memory pressure level; and
an estimated time period for the storage unit memory pressure level.

10. The storage unit of claim 9 , wherein the one or more close-out requests include:
one or more write finalize requests; and
one or more cleanup requests.

11. The storage unit of claim 9 , wherein the one or more no-contest requests include:
one or more read requests;
one or more delete requests;
one or more list requests; and
one or more edit requests.

12. The storage unit of claim 7 , wherein the data access request includes a slice name for the encoded data slice, a transaction number, a type of request, and a current revision level of the encoded data slice.

Assignees

• IBM

Inventors

• Vedpathak Yogesh R
• Farrell Brian S
• Li Mingyu

Classifications

• G06F3/067 Primary

  Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS] · CPC title

• G06F11/1076

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

• G06F3/0613

  in relation to throughput · CPC title

• G06F3/0659 Primary

  Command handling arrangements, e.g. command buffers, queues, command scheduling · CPC title