Andrea Spadaccini

The technical side of Site Reliability Engineering is reasonably well-understood and documented. There are now a significant number of books, articles, and conferences that deal with how to reason about, operate and improve the reliability of large-scale distributed systems. However, the dynamics of SRE teams themselves are less discussed. Effectively operating an SRE team or organization is very rewarding, but can also be very challenging.

In this article, I will share five lessons I… Visualizza altro

The technical side of Site Reliability Engineering is reasonably well-understood and documented. There are now a significant number of books, articles, and conferences that deal with how to reason about, operate and improve the reliability of large-scale distributed systems. However, the dynamics of SRE teams themselves are less discussed. Effectively operating an SRE team or organization is very rewarding, but can also be very challenging.

In this article, I will share five lessons I learned about starting SRE teams (or engagements, or organizations). There will be a follow-up piece containing five lessons I learned about sustaining healthy SRE engagements at steady state. I presented a talk version of these articles at SRECon21. Meno dettagli

Talk delivered at SRECon21. Slides: https://www.usenix.org/system/files/srecon21_slides_spadaccini.pdf

Abstract:
In this talk we'll discuss some key principles and lessons learned that I've developed and refined in more than 10 years of experience as a Site Reliability Engineer across several teams within Google and Microsoft.

These are topics that often come up as I discuss Site Reliability Engineering with Microsoft customers that are at different stages of their own SRE… Visualizza altro

Talk delivered at SRECon21. Slides: https://www.usenix.org/system/files/srecon21_slides_spadaccini.pdf

Abstract:
In this talk we'll discuss some key principles and lessons learned that I've developed and refined in more than 10 years of experience as a Site Reliability Engineer across several teams within Google and Microsoft.

These are topics that often come up as I discuss Site Reliability Engineering with Microsoft customers that are at different stages of their own SRE journey, and that they—hopefully!—find insightful. They broadly belong to the areas of "Starting SRE" and "Steady-state SRE."

Please join us if you want to discuss fundamental principles of adopting SRE, want to listen to my mistakes (so you can avoid making them!), and want to compare notes on different ways of doing SRE. Meno dettagli

Co-author of Chapter 8 in O'Reilly's "Site Reliability Workbook", titled "On-Call".

I focused mostly on the relationships with the chapter on On-Call in the first SRE book and on the section on on-call flexibility, an ever important topic to make on-call work more inclusive.

This tutorial offers attendees practical experience with the issues surrounding large-scale system design, presented by Andrea Spadaccini and other members of Google’s Site Reliability Engineering (SRE) team. You’ll learn how to take a problem such as “design imgur,” reason about what designs would be appropriate, figure out how to implement them (what is required in terms of machines, network bandwidth, how site reliability concerns influence the implementation, some discussion of distributed… Visualizza altro

This tutorial offers attendees practical experience with the issues surrounding large-scale system design, presented by Andrea Spadaccini and other members of Google’s Site Reliability Engineering (SRE) team. You’ll learn how to take a problem such as “design imgur,” reason about what designs would be appropriate, figure out how to implement them (what is required in terms of machines, network bandwidth, how site reliability concerns influence the implementation, some discussion of distributed systems design patterns and Paxos, etc.), discuss this in group session, and communicate these suggestions to Andrea. Each group will have a facilitator to help keep things efficient. You’ll leave with stronger analysis skills and awareness of technologies and approaches for large-scale design. Meno dettagli

This was not a publication, but rather a workshop held in collaboration with several other Google SRE colleagues. Abstract: "Participants will have the opportunity to try their hand on designing a reliable, distributed, multi-datacenter near-real-time log processing system. The session will start with a short presentation on lessons learned about designing reliable distributed systems, and then participants will break out in small groups, assisted by Google facilitators, and try their hand at… Visualizza altro

This was not a publication, but rather a workshop held in collaboration with several other Google SRE colleagues. Abstract: "Participants will have the opportunity to try their hand on designing a reliable, distributed, multi-datacenter near-real-time log processing system. The session will start with a short presentation on lessons learned about designing reliable distributed systems, and then participants will break out in small groups, assisted by Google facilitators, and try their hand at solving a real-world design challenge, from high-level architecture down to an estimate of the computing resources required to run the service." Meno dettagli

Chapter 11 in the O'Reilly book "Site Reliability Engineering", written by members of the SRE team at Google. It is a slightly edited version of the USENIX ;login: article "Being an On-Call Engineer: A Google SRE Perspective".

A free version of the chapter is available here: https://landing.google.com/sre/book/chapters/being-on-call.html

Being on-call is a critical duty that many operations and engineering teams must undertake in order to keep their services reliable and available. However, there are several pitfalls in the organization of on-call rotations and responsibilities that can lead to serious consequences for the services and for the teams if not avoided. We provide the primary tenets of the approach to on-call that Google’s Site Reliability Engineers have developed over years, and explain how that approach has led to… Visualizza altro

Being on-call is a critical duty that many operations and engineering teams must undertake in order to keep their services reliable and available. However, there are several pitfalls in the organization of on-call rotations and responsibilities that can lead to serious consequences for the services and for the teams if not avoided. We provide the primary tenets of the approach to on-call that Google’s Site Reliability Engineers have developed over years, and explain how that approach has led to reliable services and sustainable workload over time. Meno dettagli

The topics of computer architecture are always
taught using an Assembly dialect as an example. The most
commonly-used textbooks in this field use the MIPS64 Instruction
Set Architecture (ISA) to help students in learning the funda-
mentals of computer architecture, because of its orthogonality
and its suitability for real-world applications.
This paper shows how to use the EduMIPS64 visual CPU
Simulator as a supporting tool for teaching the standard topics
covered by an… Visualizza altro

The topics of computer architecture are always
taught using an Assembly dialect as an example. The most
commonly-used textbooks in this field use the MIPS64 Instruction
Set Architecture (ISA) to help students in learning the funda-
mentals of computer architecture, because of its orthogonality
and its suitability for real-world applications.
This paper shows how to use the EduMIPS64 visual CPU
Simulator as a supporting tool for teaching the standard topics
covered by an undergraduate course in computer architecture.
The proposed approach is first compared with other similar
works in the field, then, after a short description of the simulator,
the paper focuses on how it can be used for teaching specific
topics in an undergraduate computer architecture course.
This discussion is then followed by a quantitative assessment of
the suitability of the simulator, by means of a survey compiled by
students themselves; the results show that EduMIPS64 is suitable
for the purpose for which it was built, that is, supporting the
learning process of computer architecture topics. Meno dettagli

Book chapter in the "Biometrics" Book, by InTech Open Access publishers, ISBN 978-953-307-618-8.

The aim of the chapter is to introduce the reader to the usage of heart sounds for biometric recognition, describing the strengths and the weaknesses of this novel trait and analyzing in detail the methods developed so far and their performance.

This is a paper about the usage of EduMIPS64 in undergraduate Computer Architecture courses.

One of the most recent innovations in the field of biometric recognition is the usage of heart sounds as physiological traits for identity verification. In this paper, we propose a statistical approach, supported by Gaussian Mixture Models, to the the problem of biometric identity verification based on heart sounds. The system is validated on a database of heart sounds acquired from 147 people, and shows a significant performance improvement with respect to other approaches, yielding an Equal… Visualizza altro

One of the most recent innovations in the field of biometric recognition is the usage of heart sounds as physiological traits for identity verification. In this paper, we propose a statistical approach, supported by Gaussian Mixture Models, to the the problem of biometric identity verification based on heart sounds. The system is validated on a database of heart sounds acquired from 147 people, and shows a significant performance improvement with respect to other approaches, yielding an Equal Error Rate of 15.53 % Meno dettagli

This paper presents an evolution of a biometric identity verification system based on heart sounds. The system is built using Gaussian Mixture Models (GMMs) and uses features extracted both from the spectral domain and the time domain in order to
improve the performance, measured in terms of Equal Error Rate (EER), with respect to similar systems. The best result obtained using our approach, computed over a database of 165 people, is an EER of 13,70 %, that outperforms other similar… Visualizza altro

This paper presents an evolution of a biometric identity verification system based on heart sounds. The system is built using Gaussian Mixture Models (GMMs) and uses features extracted both from the spectral domain and the time domain in order to
improve the performance, measured in terms of Equal Error Rate (EER), with respect to similar systems. The best result obtained using our approach, computed over a database of 165 people, is an EER of 13,70 %, that outperforms other similar approaches. Meno dettagli

This paper presents a performance evaluation of a speech biometry system based on the statistical models GMM (Gaussian Mixture Models). In particular, the paper underlines the robustness to the degradation of various natural noises, and their impact on the system. Finally, the impact of the duration to both training and test sequences is highlighted. Results show that the noise can have the impact on the degradation of the performance (see EER values) which vary from 100 % to 300 % on the basis… Visualizza altro

This paper presents a performance evaluation of a speech biometry system based on the statistical models GMM (Gaussian Mixture Models). In particular, the paper underlines the robustness to the degradation of various natural noises, and their impact on the system. Finally, the impact of the duration to both training and test sequences is highlighted. Results show that the noise can have the impact on the degradation of the performance (see EER values) which vary from 100 % to 300 % on the basis of the type
of noise which depends on only one of two compared sequences. The duration of the sequences is a very important parameter, mostly for training phase, for which it is necessary to have at least 25 seconds long talk. Meno dettagli

Speech signal quality is of fundamental importance for accurate speaker identification. The reliability of a speech biometry system, in fact, is known to depend on the amount of material available, in particular on the number of vowels present in the sequence being analysed and on the quality of the signal. This paper highlights the performance of two Signal-to-Noise Ratio (SNR) estimation methods (manual and semi-automatic) usually adopted for the evaluation of speech signal quality. The… Visualizza altro

Speech signal quality is of fundamental importance for accurate speaker identification. The reliability of a speech biometry system, in fact, is known to depend on the amount of material available, in particular on the number of vowels present in the sequence being analysed and on the quality of the signal. This paper highlights the performance of two Signal-to-Noise Ratio (SNR) estimation methods (manual and semi-automatic) usually adopted for the evaluation of speech signal quality. The results not only demonstrate the different impact of noise on the single vowels, but also show that often the SNR is over-estimated or under-
estimated, and this leads respectively to the inclusion of bad quality biometric samples or the exclusion of good quality data, with a negative impact on the accuracy of the identity verification test. The paper proposes a series of issues that need to be tackled in order to develop a better procedure for the selection of biometric samples extracted from the intercepted audio signal Meno dettagli

In this paper we propose a cardiac biometric system for human identity verification based on an automatic selection algorithm of the best subsequence of a DHS (Digital Heart Sound) signal. The quality score is based on the cepstral distance between homogeneous cardiac sounds.
Performance of the algorithm proposed, expressed in terms of equal error rate, is similar to a DHS manual segmentation-based system, but offers the advantages of a fully automatic biometric application.

This paper presents new results in human identity verification via frequency analysis of cardiac sounds. More specifically, the paper proposes a pattern recognition approach based on a feature set of 13 Mel Frequency Cepstral Coefficients (MFCCs) extracted from the first (S1) and second (S2) heart sounds and a metric based on the power ratio of S1 to S2. The new algorithm yields significantly better performances with respect to the previous method based on the Chirp z-transform, guaranteeing an… Visualizza altro

This paper presents new results in human identity verification via frequency analysis of cardiac sounds. More specifically, the paper proposes a pattern recognition approach based on a feature set of 13 Mel Frequency Cepstral Coefficients (MFCCs) extracted from the first (S1) and second (S2) heart sounds and a metric based on the power ratio of S1 to S2. The new algorithm yields significantly better performances with respect to the previous method based on the Chirp z-transform, guaranteeing an equal error rate (EER) below 9 %. Meno dettagli

This article describes JECT-OMR, a system that analyzes digital images representing scans of multiple-choice tests compiled by students. The system performs a structural analysis of the document in order to get the chosen answer for each question,
and it also contains a bar-code decoder, used for the identification of additional information encoded in the document. JECT-OMR was implemented using the Python programming language, and leverages the power of the Gamera framework in order to… Visualizza altro

This article describes JECT-OMR, a system that analyzes digital images representing scans of multiple-choice tests compiled by students. The system performs a structural analysis of the document in order to get the chosen answer for each question,
and it also contains a bar-code decoder, used for the identification of additional information encoded in the document. JECT-OMR was implemented using the Python programming language, and leverages the power of the Gamera framework in order to accomplish its task. The system exhibits an accuracy of over 99% in the recognition of marked and non-marked squares representing answers, thus making it suitable for real world applications. Meno dettagli

In this paper we introduce HSCT-11, an open dataset containing data collected from 206 people that can be used for performance evaluation of heart sounds biometric systems, and we use it to benchmark two such systems. The most performing one shows an Equal Error Rate (EER) of 13.66%, a result that can be used as a baseline for future evaluations made using this dataset.