Designing transformer oil immersion cooling servers for machine learning and first principle calculations

Keisuke Takahashi; Itsuki Miyazato; Satoshi Maeda; Lauren Takahashi

doi:10.1371/journal.pone.0266880

Peer Review History

Original SubmissionNovember 5, 2021
20 Jan 2022 Decision Letter - Mohammad Ali Haider, Editor PONE-D-21-35184Designing Transformer Oil Immersion Cooling Servers for Machine Learning and First Principle CalculationsPLOS ONE Dear Dr. Takahashi, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Mar 06 2022 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. 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Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf. 4. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: No Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: Computational servers are important in almost all fields of science and technology. These servers generate large amount of heat. Efficient cooling is required to keep the servers functional for a longer period of time. The performance of heated servers usually goes down. In this paper, authors have put their efforts in solving the issue of heated servers and have tried to use transformer oil as a heat sink. Authors have reported that speed of first principle calculations and machine learning applications are better in servers which are immersed in transformer oils. This is really a nice piece of work however authors are requested to clarify few doubts: • Authors report that the server is functional in the oil. Did they use any type of coating on the server to protect the machine? • Authors see an improvement in server’s performance after keeping it inside the transformer oil. Authors should explain the reason behind this finding. • Authors get better results in multi-core machines. The reason behind this observation is missing. • It is also interesting to know if the same oil can be recycled again and for how many times. Reviewer #2: Abstract: CPU, motherboard, ...... are submerged into the transformer oil. Authors intent here is not clear. Need to reconstructed. What is feasibility of transformer oil immersion cooling servers in real world considering implementation challenges? Introduction: unnecessary citations for will known facts should be avoided. Methods: It is not clear how heat from transformer oil would be removed? All other systems have circulation in place which continuously removes heat but herein no such details are mentioned. Experimental results could have been explained more especially effect of heating on density and viscosity. What is the effect of rise in temperature on the physical properties of the fluid. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review?** For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. Attachments Attachment Submitted filename: Comment.pdf https://doi.org/10.1371/journal.pone.0266880.r001
Revision 1
9 Mar 2022 Author Response Dear Editors of PLOS ONE, I have carried out revisions throughout the manuscript on the basis of the reviewers' comments. Comments to the reviewers are colored in red and mentioned after =>. If there are any questions or concerns, please do not hesitate to contact me. I'm more than happy to revise the manuscript. Best regards, Keisuke Takahashi Ph.D. Keisuke Takahashi Department of Chemistry, Hokkaido University, North 10, West 8, Sapporo 060-8510, Japan Here is the answers to reviewers comment. Editorial Edit: 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at => Fixed 2- Please note that funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form. => Fixed 3-Please state what role the funders took in the study. If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript." => Contribution is now witten 4- Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. => Confirmed Reviewer 1: Computational servers are important in almost all fields of science and technology. These servers generate large amount of heat. Efficient cooling is required to keep the servers functional for a longer period of time. The performance of heated servers usually goes down. In this paper, authors have put their efforts in solving the issue of heated servers and have tried to use transformer oil as a heat sink. Authors have reported that speed of first principle calculations and machine learning applications are better in servers which are immersed in transformer oils. This is really a nice piece of work however authors are requested to clarify few doubts: • Authors report that the server is functional in the oil. Did they use any type of coating on the server to protect the machine? => We haven't applied any coating. We added the following sentence. “Note that the server is not treated with a protective coating before being submerged in the oil.” • Authors see an improvement in server’s performance after keeping it inside the transformer oil. Authors should explain the reason behind this finding. => We believe that the transformer oil act as a heat sink.We added the following sentence. “More importantly, not only is the CPU cooled by the oil but all other parts of the server are also simultaneously cooled by the transformer oil, thus, the oil acts as a heat sink.” • Authors get better results in multi-core machines. The reason behind this observation is missing. The multi-core process generates more heat than the single core process. From this, we can consider the effect of cooling to be more crucial. We have added the following to the manuscript. " Considering that multi-core calculations can generate more heat than single cores, one can believe that the transformer oil can contribute towards lowering the sever temperature, thereby resulting in better performance.." • It is also interesting to know if the same oil can be recycled again and for how many times. =>One of the drawbacks of the transformer oil is oxidation. As time passes, oxidation can potentially affect the durability of the oil. We have added the following sentence to the manuscript. "It must be noted that server lifetime within the transformer oil must still be evaluated as there is possibility of the oil corroding the cables and plastics within the server." ******************************************************************************** Reviewer 2: Abstract: CPU, motherboard, ...... are submerged into the transformer oil. Authors intent here is not clear. Need to reconstructed. => We meant that we wanted to cool the entire system where normally CPU is only cooled. We have added the following sentence to the abstruct. “CPU, motherboard, random access memory, hard disk drive, solid state drive, graphic card, and the power supply unit are submerged into the transformer oil in order to cool the entire system.” What is feasibility of transformer oil immersion cooling servers in real world considering implementation challenges? => The challenge would be lifetime and oxidation. One of the drawbacks of the transformer oil is oxidation. As time passes, oxidation can potentially affect the durability of the oil. We have added the following sentence to the manuscript. "It must be noted that server lifetime within the transformer oil must still be evaluated as there is possibility of the oil corroding the cables and plastics within the server. One of the drawbacks of the transformer oil could be oxidation. As time passes, oxidation can potentially affect the durability of the oil. Further study is required to better understand the effects oxidation can have upon performance and durability of the oil over a longer period of time" Introduction: unnecessary citations for will known facts should be avoided. => All citations at introduction are about materials informatics and computational materials science/Chemistry/physics now. Methods: It is not clear how heat from transformer oil would be removed? All other systems have circulation in place which continuously removes heat but herein no such details are mentioned. => Thank you for pointing this out. Both of power supply unit and graphic card have fans. Those fans create the circulation flow within the transformer oil, thus, heat is continuously removed.We have added the following to the manuscript. “Both of power supply unit and graphic card have fans. Those fans create the circulation flow within the transformer oil, thus, heat is continuously removed.” Experimental results could have been explained more especially effect of heating on density and viscosity. What is the effect of rise in temperature on the physical properties of the fluid. => It is quite challenging to identify exact physical properies of the fluid. However, as reviewers suggested, kinematic viscosity explains this well. In particular, kinematic viscosity of the transformer oil in this work is 8.09 mm2/s at 40C while its 2.21 mm2/s at 100C. This shows that kinematic viscosity become approximately ¼ with increase of 60C. In another word, low viscosity enable to circulate the fliud easily compared to high viscosity. Thus, low viscosity upon the rise of tempeature is one of the main feature of this work. The following sentences are now added. “"The rise in temperature is found to affect the viscosity of the oil in a manner that can be seen as beneficial for the server. To start, the kinematic viscosity of the transformer oil is reported to be 8.09 mm2/s at 40C and decreases to 2.21 mm2/s when at 100C. This demonstrates that by increasing temperature, the kinematic viscosity decreases to 1/4 of its original viscosity with an increase of 60C. The server is potentially benefitting this as low viscosity allows for fluid to circulate much easier when compared to high viscosity. As the server runs and generates heat, the viscosity of the oil decreases and improves fluid circulation, which can thus help remove the heat from the server and help keep the server cool. "” Attachments Attachment Submitted filename: comments to reviewer_final_revised.docx https://doi.org/10.1371/journal.pone.0266880.r002
30 Mar 2022 Decision Letter - Mohammad Ali Haider, Editor Designing Transformer Oil Immersion Cooling Servers for Machine Learning and First Principle Calculations PONE-D-21-35184R1 Dear Dr. Takahashi, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Mohammad Ali Haider, Ph.D. Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0266880.r003
Formally Accepted
12 Apr 2022 Acceptance Letter - Mohammad Ali Haider, Editor PONE-D-21-35184R1 Designing Transformer Oil Immersion Cooling Servers for Machine Learning and First Principle Calculations Dear Dr. Takahashi: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Mohammad Ali Haider Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0266880.r004

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