University of Illinois Urbana-Champaign

Current Projects

Real-time data infrastructure.

New fault-tolerant logging abstractions.

CXL memory systems.

Agent-first data infrastructure.

Explore publications Join the lab

News

  • Congrats Kiran on winning the Distinguised Shadow PC Reviewer Award at EuroSys 26!
  • Congrats Michael on NSF GRFP!
  • Our work on partly coherent CXL memory sharing has been accepted to OSDI 26. Congrats Jiyu, Seokjoo, Landon, Kiran and Shreesha!
  • Our work on logically disaggregated caches has been accepted to EuroSys 26. Congrats Kiran, Henry, Shreesha, Neil!
  • Congrats Henry on passing the PhD qualification exam!
  • We will present our work on shared logs/streaming at Confluent Current 2025 and StreamNative Data Streaming Summit!
  • LazyLog accepted to ACM Transactions on Computer Systems
  • Ram gave a talk about our work on shared log at Systems Distributed 25!
  • Thank you TigerBeetle for supporting our work via a research gift!
  • Congrats Xuhao on passing the prelim exam!
  • Congrats Jiyu, Kiran, and Shreesha on passing the PhD qualification exam!
  • Our work on low end-to-end latency atop shared logs will appear in OSDI 25. Congrats Shreesha, Tony, Xuhao, and Jiyu!
  • Ram Alagappan was awarded a NetApp Faculty Fellowship!
  • Our paper "LazyLog: A New Shared Log Abstraction for Low-Latency Applications" won a Best Paper Award at SOSP 24!
  • Our work on low-latency shared logs will appear in SOSP 24. Congrats Xuhao, Shreesha, and Jiyu!
  • Ram Alagappan wins the NSF CAREER Award!
  • Aishwarya Ganesan wins the NSF CAREER Award!
  • Our work on high-performance KV-store replication will appear in Fast '24. Congrats Henry!
  • Congrats Xuhao on passing his PhD qualification exam!
  • Our work on disaggregated storage fault-tolerance will appear in EuroSys '24. Congrats Xuhao!
  • Aishwarya and Ram were interviewed by TigerBeetle's CEO Joran, and Chaitanya (who interned there) - Video.

People

Xuhao Luo

Xuhao Luo

PhD student · Started Spring 2023

Jiyu Hu

Jiyu Hu

PhD student · Started Fall 2023

Landon Johnson

Landon Johnson

PhD student · Started Fall 2025

Alumni

  • Tony Hong (Visiting Researcher)
  • Chaitanya Bhandari (MS student)
  • Ramya Bygari (MS student)
  • Neil Kaushikkar (undergrad thesis)
  • Wenqing Luo (MS Thesis; First Employment: Apple)
  • Shubhi Jain (MCS student)
  • Abhi Wangoo (undergrad)
  • Akul Gupta (undergrad)
  • Amaan Khan (undergrad)

Publications

2026

Agents for Data Streaming Tasks: The Missing Pieces
Shreesha G. Bhat*, Landon Johnson*, Michael Noguera*, Aishwarya Ganesan, Ramnatthan Alagappan
*=equal contribution
CAIS '26 SAO Workshop (To Appear)

Sophrosyne: Agentic Exploration of Relational Data Systems Needs Moderation
Madhav Jivrajani, Ramnatthan Alagappan, Aishwarya Ganesan
CAIS '26 SAO Workshop (To Appear)

MEGALON: Efficient Data Sharing for Partly Coherent CXL Memory
Jiyu Hu, Seokjoo Cho*, Landon Johnson*, Kiran Hombal, Shreesha G. Bhat, Marcos K. Aguilera, Ramnatthan Alagappan, Aishwarya Ganesan
*=equal contribution
OSDI '26 (To Appear)

A Logically Disaggregated Cache for Replicated Storage Systems
Kiran Hombal, Henry Zhu, Shreesha G. Bhat, Neil Kaushikkar, Ramnatthan Alagappan, Aishwarya Ganesan
EuroSys '26
PDF

2025

LazyLog: A New Shared Log Abstraction and Design for Modern Low-Latency Applications
Xuhao Luo, Shreesha Bhat*, Jiyu Hu*, Ramnatthan Alagappan, Aishwarya Ganesan
*=equal contribution
ACM Transaction on Computer Systems
PDF

Low End-to-End Latency atop a Speculative Shared Log with Fix-Ante Ordering
Shreesha Bhat, Tony Hong, Xuhao Luo, Jiyu Hu, Aishwarya Ganesan, Ramnatthan Alagappan
OSDI '25
PDF

2024

LazyLog: A New Shared Log Abstraction for Low-Latency Applications
Xuhao Luo, Shreesha Bhat*, Jiyu Hu*, Ramnatthan Alagappan, Aishwarya Ganesan
*=equal contribution
SOSP '24
PDF
Best Paper Award
Invited to Transactions on Computer Systems

IONIA: High-Performance Replication for Modern Disk-based KV Stores
Yi Xu*, Henry Zhu*, Prashant Pandey, Alex Conway, Rob Johnson, Aishwarya Ganesan, Ramnatthan Alagappan
*=co-primary authors.
FAST '24
PDF

SplitFT: Fault Tolerance for Disaggregated Datacenters via Remote Memory Logging
Xuhao Luo, Ramnatthan Alagappan, Aishwarya Ganesan
EuroSys '24
PDF

2022

Crash Consistency
Ramnatthan Alagappan
ACM Research for Practice July 2022
ACM RFP '22
Invited
PDF

Exploiting Nil-Externalizing Interfaces for Fast Replicated Storage
Aishwarya Ganesan, Ramnatthan Alagappan, Anthony Rebello, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Transactions on Storage - May 2022
TOS '22
Fast tracked
PDF

Automatic Reliability Testing For Cluster Management Controllers
Xudong Sun, Wenqing Luo, Tyler Gu, Aishwarya Ganesan, Ramnatthan Alagappan, Michael Gasch, Lalith Suresh, and Tianyin Xu
16th USENIX Symposium on Operating Systems Design and Implementation
OSDI '22
PDF

2021

Exploiting Nil-Externality for Fast Replicated Storage
Aishwarya Ganesan, Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
28th ACM Symposium on Operating Systems Principles
SOSP '21
PDF, Talk Slides, Video - short, Video - long, Code
Invited to Transactions on Storage

Strong and Efficient Consistency with Consistency-aware Durability
Aishwarya Ganesan, Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Transactions on Storage - Vol. 17, Issue 1, January 2021
TOS '21
Fast tracked
PDF

Can Applications Recover from fsync Failures?
Anthony Rebello, Yuvraj Patel, Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Transactions on Storage - Vol. 17, Issue 2, June 2021
TOS '21
PDF

The Storage Hierarchy is Not a Hierarchy: Optimizing Caching on Modern Storage Devices with Orthus
Kan Wu, Zhihan Guo, Guanzhou Hu, Kaiwei Tu, Ramnatthan Alagappan, Rathijit Sen, Kwanghyun Park, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
19th USENIX Conference on File and Storage Technologies
FAST '21
PDF

Reasoning about modern datacenter infrastructures using partial histories
Xudong Sun, Lalith Suresh, Aishwarya Ganesan, Ramnatthan Alagappan, Michael Gasch, Lilia Tang, Tianyin Xu
18th Workshop on Hot Topics in Operating Systems
HotOS '21
PDF

The Storage Hierarchy is Not a Hierarchy: Optimizing Caching on Modern Storage Devices with Orthus
Kan Wu, Zhihan Guo, Guanzhou Hu, Kaiwei Tu, Ramnatthan Alagappan, Rathijit Sen, Kwanghyun Park, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Non-Volatile Memory Workshop 2021
NVMW '21
PDF

2020

From Wisckey to Bourbon: A Learned Index for Log-structured Merge Trees
Yifan Dai, Yien Xu, Aishwarya Ganesan, Ramnatthan Alagappan, Brian Kroth, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Proceedings of the 14th Symposium on Operating System and Design Implementation
OSDI '20
PDF

Can Applications Recover from fsync Failures?
Anthony Rebello, Yuvraj Patel, Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
The 2020 USENIX Annual Technical Conference
ATC '20
PDF
Invited to Transactions on Storage

Strong and Efficient Consistency with Consistency-aware Durability
Aishwarya Ganesan, Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
18th USENIX Conference on File and Storage Technologies
FAST '20
PDF, Talk Slides
Best Paper Award
Invited to Transactions on Storage

Too Many Knobs to Tune? Towards Faster Database Tuning by Pre-selecting Important Knobs
Konstantinos Kannelis, Ramnatthan Alagappan, Shivaram Venkataraman
15th Workshop on Hot Topics in Storage and File Systems
HotStorage '20
PDF

2019

Protocol-Aware Recovery for Consensus-based Storage
Ramnatthan Alagappan, Aishwarya Ganesan, Eric Lee, Aws Albarghouthi, Vijay Chidambaram, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
The 2019 USENIX Annual Technical Conference
Usenix ATC '19
Best of the Rest

Geting More Performance with Polymorphism from Emerging Memory Technologies
Iyswarya Narayanan, Aishwarya Ganesan, Anirudh Badam, Sriram Govindan, Bikash Sharma, and Anand Sivasubramaniam.
In Proceedings of the 12th ACM International Conference on Systems and Storage
SYSTOR '19
PDF

2018

Fault-Tolerance, Fast and Slow: Exploiting Failure Asynchrony in Distributed Systems
Ramnatthan Alagappan, Aishwarya Ganesan, Jing Liu, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Proceedings of the 13th Symposium on Operating System and Design Implementation
OSDI '18
PDF, Talk Slides

Protocol-Aware Recovery for Consensus-Based Distributed Storage
Ramnatthan Alagappan, Aishwarya Ganesan, Eric Lee, Aws Albarghouthi, Vijay Chidambaram, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Transactions on Storage - Vol. 14, Issue 3, October 2018
TOS '18
Fast tracked
PDF

Protocol-Aware Recovery for Consensus-Based Storage
Ramnatthan Alagappan, Aishwarya Ganesan, Eric Lee, Aws Albarghouthi, Vijay Chidambaram, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Proceedings of the 16th USENIX Conference on File and Storage Technologies
FAST '18
PDF, Talk Slides
Best Paper Award
Invited to Transactions on Storage
Invited to ATC 19 Best of the Rest
Coverage: Morning Paper, zdnet

2017

Application Crash Consistency and Performance with CCFS
Thanumalayan Sankaranarayana Pillai, Ramnatthan Alagappan, Lanyue Lu, Vijay Chidambaram, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
The 2017 USENIX Annual Technical Conference
Usenix ATC '17
Best of the Rest
PDF

Atomic In-Place Updates for Non-Volatile Main Memories with KaminoTx
Amir Saman Memaripour, Anirudh Badam, Amar Phanishayee, Yanqi Zhou, Ramnatthan Alagappan, Karin Strauss, Steven Swanson
Proceedings of the Twelfth European Conference on Computer Systems
EuroSys '17
PDF

Redundancy Does Not Imply Fault Tolerance
Aishwarya Ganesan, Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Transactions on Storage - Vol. 13, Issue 3, September 2017
TOS '17
Fast tracked
PDF

Application Crash Consistency and Performance with CCFS
Thanumalayan Sankaranarayana Pillai, Ramnatthan Alagappan, Lanyue Lu, Vijay Chidambaram, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Transactions on Storage - Vol. 13, Issue 3, September 2017
TOS '17
Fast tracked
PDF

Redundancy Does Not Imply Fault Tolerance
Aishwarya Ganesan, Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
USENIX ;login: Volume 42, Number 2, 2017
USENIX ;login: Summer '17
PDF

Redundancy Does Not Imply Fault Tolerance: Analysis of Distributed Storage Reactions to Single Errors and Corruptions
Aishwarya Ganesan, Ramnatthan Alagappan, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Proceedings of the 15th USENIX Conference on File and Storage Technologies
FAST '17
PDF, Talk Slides, Code
Best Paper Award Nominee
Invited to Transactions on Storage
Invited to Usenix ;login:
Coverage: StorageMojo, Morning Paper, DHSR's blog

Application Crash Consistency and Performance with C2FS
Thanumalayan Sankaranarayana Pillai, Ramnatthan Alagappan, Lanyue Lu, Vijay Chidambaram, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Proceedings of the 15th USENIX Conference on File and Storage Technologies
FAST '17
PDF, Talk Slides
Best Paper Award
Invited to Transactions on Storage
Invited to ATC 17 Best of the Rest
Coverage: Morning Paper

Hybrid NVM Enabled Datacenter Design and Optimization
Yanqi Zhou, Ramnatthan Alagappan, Amir Samam Memaripour, Anirudh Badam, David Wentzlaff
MSR-TR-2017-8 Feb 2017
MSR TR
PDF

2016

Correlated Crash Vulnerabilities
Ramnatthan Alagappan, Aishwarya Ganesan, Yuvraj Patel, Thanumalayan Sankaranarayana Pillai, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Proceedings of the 12th Symposium on Operating System and Design Implementation
OSDI '16
PDF, Talk Slides, Code

2015

Crash Consistency
Thanumalayan Sankaranarayana Pillai, Vijay Chidambaram, Ramnatthan Alagappan, Samer Al Kiswany, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Communications of the ACM - Vol. 58, No. 10, October 2015
CACM
PDF

Crash Consistency: Rethinking the Fundamental Abstractions of the File System
Thanumalayan Sankaranarayana Pillai, Vijay Chidambaram, Ramnatthan Alagappan, Samer Al Kiswany, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
ACM Queue July 2015
ACM Queue
PDF

Beyond Storage APIs: Provable Semantics for Storage Stacks
Ramnatthan Alagappan, Vijay Chidambaram, Thanumalayan Sankaranarayana Pillai, Aws Albarghouthi, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
15th Workshop on Hot Topics in Operating Systems
HotOS '15
PDF

2014

All File Systems Are Not Created Equal: On the Complexity of Crafting Crash-Consistent Applications
Thanumalayan Sankaranarayana Pillai, Vijay Chidambaram, Ramnatthan Alagappan, Samer Al Kiswany, Andrea C. Arpaci-Dusseau, Remzi H. Arpaci-Dusseau
Proceedings of the 11th Symposium on Operating System and Design Implementation
OSDI '14
PDF, Code
Invited to Communications of the ACM
Invited to ACM Queue
Coverage: Morning Paper

Software

All our open-source software can be found at this Github repo.

Pictures

DASSL group lunch in summer 2025
Group Lunch Summer 25
DASSL at SOSP 2024
SOSP 24
Three generations together at SOSP 2024
Fun three-gens pic at SOSP 24

Join Us!

We are actively looking for strong and self-motivated PhD students to join DASSL at UIUC. Please apply to the UIUC CS PhD program and mention Aishwarya Ganesan (aganesn2@illinois.edu) or Ram Alagappan (ramn@illinois.edu) as potential advisors in your application. UIUC has a stellar systems group (see csrankings) that you can be a part of and contribute.