XRootD: Code review for ReadV implementation in XrdCeph (March 2023)

📋 Overview

Submitter	Alexander Rogovskiy
Status	NOT STARTED
Reviewers	James Walder
Goals	Review the code for the ReadV changes and identify any further tests / updates that are required. Discuss the packaging, deployment and post-deployment testing; and included any discussion on risk factors
Change Control	https://stfc.atlassian.net/wiki/spaces/GRIDPP/pages/137265343/Non-striper+read+v+implementation+for+WN+s+xrootd+gateways
Jira tickets
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🎯 Requirements

Summary statement

Improve xrootd’s read and readv implementation for WN’s gateways to allow them effectively handle vector read operations

Problem statements

Vector read (aka readv) operations on ECHO storage are not very efficient. Oftentimes a single readv requests with cumulative size of several megabytes takes up to 1 minute or more. This causes a lot of problems, especially for LHCb VO.

Success metrics

Allow for readV access with failures at a level no worse than at other sites. Do not worsen Read performance.

Meeting Dates:

Summary of meeting times and main participants:

Meeting 1 - Tues 21 March 2023; Present:

📸 Review Changes:

Design decision template.

	Repo	Change description	Comments
1	https://github.com/stfc/xrootd-ceph/pull/37
2	https://github.com/alex-rg/xrootd/tree/readv_timeout	The last two commits are my changes related to timeout increase	These need to go into a PR in appropriate place in STFC/xrootd repo

❓ Open issues

Questions that arise during the review should be largely addressed in the appropriate github PR review process. Summaries of main issues arising from the review should be noted below

🧪 Test results

A summary of the test suites that have been run, and any issues that have arisen. New tests that are requested can be documented here. Can either be presented as a link to a test suite page or direct summary of each of the tests.

Scenario / test name	Results	What we know	What we need to learn
Functional tests	Pass	How to run the tests: 1. Set up TEST_FILE_URL environment variable 2. Set up FILE_BLOCK_SIZE environment variable 3. Run py.test

?? Deployment plan

Attempt to capture the steps necessary to deploy the changes into production. Noting any particular cases for side-effects to be observed and where dependencies in / from other packages / services might be relevant.

	Date	Plan type	Target segment	Notes	Action items
1		TEST / FEATURE FLAG / OTHER
2