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Elastic memory for improved RAS and performance

IP.com Disclosure Number: IPCOM000244706D
Publication Date: 2016-Jan-06
Document File: 3 page(s) / 88K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method in the area of memory subsystem aims to improve system performance and RAS by leveraging the excess memory resources

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Page 01 of 3

Elastic memory for improved RAS and performance Background:

Server systems offer variety of features to cater the dynamic memory requirements needed by the customers in order to meet peak performance demands
Some of the features need disruption of computer service (system down) for upgrade of memory (offline upgrade) and then system needs to be powered on to account for these additional memory modules for use
Capacity upgrade On Demand (CuOD) is a feature that supports the memory expansion dynamically without needing system shutdown.

On/Off Capacity on Demand (CoD) allows customers to temporarily activate and deactivate processor cores and memory units to help meet the peak demands.

   - It involves request and approval process and usage is charged at constant intervals
Trial capacity on demand allows customers to evaluate the use of inactive memory at no charge

- Trial period is available for 30 power-on days


Memory sparing is a technique in which on-demand inactive memory is automatically activated by the system to temporarily replace failed memory until a service action can be performed.

Scrub is another important RAS feature of memory subsystem. It aims to detect soft error rates and correct them

- Before the customer main line read detects errors


Though scrub provides benefit in terms of increased RAS, it has the below drawbacks:

     - Reading the data consumes power - Additional logic in the memory controller to mange the read operation by inserting cycles in the scheduler queue

Growing trends on the memory subsystem memory capacity has an impact on the above mentioned drawbacks
Mirroring is another excellent scheme to improve availability of data by having mainline data written into two copies: primary and secondary
On demand feature, when activated, improves the overall system performance by engaging the additional resources. RAS features (mirroring, scrub and so on) improve the availability of reliable data.

When CoD usage is not committed, the additional memory resources would be unutilized. During initial system power ON, all the memory modules will be enabled and kept ready for future use. This early activation of memory modules comes with the penalty of burning excessive power throughout the system usage (runtime conditions), which is undesirable
If these additional resources can be utilized for several other mainline and non mainline system functi...