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1 -00 - How to login to Maxwell
1 +Reconstruction Guideline
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1 -The DESY has a quite powerful compute cluster called the Maxwell cluster. The documentation can be found here [[https:~~/~~/confluence.desy.de/display/MXW/Maxwell+Cluster>>doc:MXW.Maxwell Cluster.WebHome||shape="rect"]], however as this can be confusing sometimes, we will try to condensate this to a step by step manual.
1 += {{id name="00-HowtologintoMaxwell-ShortVersion:"/}}**Short Version: ** =
2 2  
3 +Terminal:
3 3  
5 +salloc ~-~-partition=all ~-~-nodes=1 –time=06:00:00
4 4  
5 -{{toc/}}
7 +ssh max-bla123
6 6  
7 -= {{id name="00-HowtologintoMaxwell-GettingaDESYAccount"/}}Getting a DESY Account =
9 +module load anaconda
8 8  
9 -During you beamtime you will encounter multiple systems, where you will need two different types of accounts:
11 +source activate ~~/envs/tomopy
10 10  
11 -== {{id name="00-HowtologintoMaxwell-TheDOORAccount"/}}The DOOR Account ==
13 +spyder&
12 12  
13 -Before you arrive you have to create a DOOR account and do all the safety trainings. This account is also being used for the gamma-portal, where you can manage you beamtime data, grant access to other users and manage FTP access. However this account does not work with other resources. For this you will have to request a second account:
15 +\\
14 14  
15 -== {{id name="00-HowtologintoMaxwell-ThePSXAccount"/}}The PSX Account ==
17 +Spyder:
16 16  
17 -If you decide during a beamtime, you want to have access to the cluster, tell your local contact so, and they will request a PSX account for you. With this you will get access to the Kerberos, Windows and afs resources at DESY, which includes the cluster.
19 +Open RecoGUI,
18 18  
19 -= {{id name="00-HowtologintoMaxwell-UsingtheCluster"/}}Using the Cluster =
21 +(Right click on tab: "Set console working directory") (to be removed)
20 20  
21 -== {{id name="00-HowtologintoMaxwell-StructureoftheCluster"/}}Structure of the Cluster ==
23 +Green Arrow to start program
22 22  
23 -=== {{id name="00-HowtologintoMaxwell-Overview"/}}Overview ===
25 +\\
24 24  
25 -The Maxwell Cluster has (status 2021) more than 750 nodes in it. To organize this, you cannot access any node directly, but you have to request compute resources at first. You then can connect form an entrance node to you compute node
27 += {{id name="00-HowtologintoMaxwell-LongVersion:"/}}**Long Version: ** =
26 26  
27 -=== {{id name="00-HowtologintoMaxwell-EntranceNodes"/}}Entrance Nodes ===
29 +\\
28 28  
29 -If you have successfully obtained an PSX account you can get started. The entrance node are:
30 -\\[[https:~~/~~/max-nova.desy.de:3443/auth/ssh>>url:https://max-nova.desy.de:3443/auth/ssh||shape="rect"]]  (if you have access to the nova resources, most likely the case if your beamtime was in cooperation with the Helmholtz Zentrum Hereon)
31 +**Login to max-nova**: E.g. from browser [[https:~~/~~/max-nova.desy.de:3443/>>url:https://max-nova.desy.de:3443/auth/ssh||shape="rect"]]
31 31  
32 -[[https:~~/~~/max-display.desy.de:3443/auth/ssh>>url:https://max-display.desy.de:3443/auth/ssh||shape="rect"]]  (in any case)
33 +\\
33 33  
34 -These nodes are **not **for processing, as you will share them with many other users. So please do not do anything computational intensive on them, like reconstruction or visualization. Viewing images is ok.
35 +Click on "**Launch Session**" and "**XFCE**" Icon
35 35  
36 -=== {{id name="00-HowtologintoMaxwell-FastX2"/}}Fast X2 ===
37 +[[image:attach:image2021-4-27_13-55-52.png||height="250"]]
37 37  
38 -The cluster uses the software FastX2 for connection and virtual desktop. To get the right version of this, use the web interface, log in, and in the bottom right corner is a download link for the desktop client. The version has to match exactly to work properly.
39 -
40 -If you want to add a connection in the desktop client, click the plus, select web, use the address above (including the port), and your username and force ssh authentication. Then you can choose if you want a virtual desktop (XFCE) or a terminal.
41 -
42 -=== {{id name="00-HowtologintoMaxwell-Partitions"/}}Partitions ===
43 -
44 -Starting from an entrance node, you can connect to a compute node. As there are multiple levels of priorities etc. the nodes are organizes in partitions. You can only access some of these. To view which one, open a terminal and use the commad:
45 -
46 -{{code}}
47 -my-partitions
48 -{{/code}}
49 -
50 -Your result will look something like this:
51 -
52 -[[image:attach:P5I.User Guide\: NanoCT.4\. Reconstruction Guide.00 - How to login to Maxwell.WebHome@image2021-5-4_10-28-14.png||queryString="version=1&modificationDate=1620116894626&api=v2" alt="image2021-5-4_10-28-14.png"]]
53 -
54 -== {{id name="00-HowtologintoMaxwell-SLURM"/}}SLURM ==
55 -
56 -The access to the resources of the cluster is managed via a scheduler, SLURM.
57 -
58 -SLURM schedules the access to nodes and can revokes access if higher priority jobs come.
59 -
60 -=== {{id name="00-HowtologintoMaxwell-PSXPartition"/}}PSX Partition ===
61 -
62 -Here you cannot be kicked out of your allocation. However, only few nodes are in this partition and you can also only allocate few in parallel (2021: 5). Some of them have GPUs available.
63 -
64 -=== {{id name="00-HowtologintoMaxwell-AllPartition"/}}All Partition ===
65 -
66 -Very large number of nodes available and you can allocate many in parallel (2021: 100). However each allocation can be revoked without a warning if s.o. with higher priority comes. This is very common to happen. If you want to use this partition, be sure to design your job accordingly. Only CPU nodes.
67 -
68 -=== {{id name="00-HowtologintoMaxwell-AllgpuPartition"/}}Allgpu Partition ===
69 -
70 -Like all, but with GPUs
71 -
72 -=== {{id name="00-HowtologintoMaxwell-JhubPartition"/}}Jhub Partition ===
73 -
74 -For Jupyter Hub
75 -
76 76  \\
77 77  
78 -== {{id name="00-HowtologintoMaxwell-ConnectingtotheCluster"/}}Connecting to the Cluster ==
41 +**Open a Terminal**, e.g. from the icon at the bottom of your desktop. You can also open it via right click → "Open Terminal here" directly on your desktop or from any folder.
79 79  
80 -Connect to an entrance node via FastX. You will automatically be assigned to a node when you start a session via a load balancer (max-display001-003, max-nova001-002)
43 +[[image:attach:image2021-4-27_13-58-35.png||height="250"]]
81 81  
82 -[[image:attach:P5I.User Guide\: NanoCT.4\. Reconstruction Guide.00 - How to login to Maxwell.WebHome@image2021-4-27_13-55-52.png||queryString="version=1&modificationDate=1619524552546&api=v2" alt="image2021-4-27_13-55-52.png"]]
83 -
84 -Choose a graphic interface and look around.
85 -
86 86  \\
87 87  
88 -== {{id name="00-HowtologintoMaxwell-DataStorage"/}}Data Storage ==
47 +Now you can **allocate a node** for yourself, so you will have enough memory and power for your reconstruction.
89 89  
90 -The Maxwell cluster knows many storage systems. The most important are:
49 +(% class="code" %)
50 +(((
51 +salloc ~-~-partition=all ~-~-nodes=1 ~-~-time=06:00:00
52 +)))
91 91  
92 -Your User Folder: This has a hard limit of 30 GB. Be sure not to exceed this.
93 -
94 -The GPFS: here all the beamtime data are stored.
95 -
96 -=== {{id name="00-HowtologintoMaxwell-GPFS"/}}GPFS ===
97 -
98 -Usually you can find you data at: /asap3/petra3/gpfs/<beamline>/<year>/data/<beamtime_id>
99 -
100 -In there you will find a substructure:
101 -
102 -* raw: raw measurement data. Only applicant and beamtime leader can write/delete there
103 -* processed: for all processed data
104 -* scratch_cc: scratch folder w/o backup
105 -* shared: for everything else
106 -
107 -The GPFS has regular snapshots. The whole capacity of this is huge (several PB)
108 -
109 -== {{id name="00-HowtologintoMaxwell-HowtoGetaComputeNode"/}}How to Get a Compute Node ==
110 -
111 -If you want to do some processing, there are two ways to start a job in SLURM:
112 -
113 -1. Interactive
114 -1. Batch
115 -
116 -In both cases you are the only person working on the node, so use it as much as you like.
117 -
118 -=== {{id name="00-HowtologintoMaxwell-StartinganInteractiveJob"/}}Starting an Interactive Job ===
119 -
120 -To get a node you have to allocate one via SLURM e.g. use:
121 -
122 -{{code}}
123 -salloc -N 1 -p psx -t 1-05:00:00
124 -{{/code}}
125 -
126 -Looking at the individual options:
127 -
128 -* salloc: specifies you want a live allocation
129 -* -N 1: for one node
130 -* -p psx: on the psx partition. You can also add multiple separated with a comma: -p psx,all
131 -* -t 1-05:00:00: for the duration of 1 day and 5h
132 -* Other options could be: ~-~-mem=500GB with at least 500GB of memory
133 -* ... see the SLURM documentation for more options
134 -
135 -If your job is scheduled you see your assigned node and can connect via ssh to it. (in the rare case where you do not see anything use my-jobs to find out the host name).
136 -
137 -=== {{id name="00-HowtologintoMaxwell-Startingabatchjob"/}}Starting a batch job ===
138 -
139 -For a batch job you need a small shell script describing what you want to do. You do not see the job directly, but the output is written to a log file (and results can be stored on disk)
140 -
141 -With a batch job, you can also start an array job, where the same task is executed on multiple servers in parallel.
142 -
143 -An example for such a script:
144 -
145 -{{code}}
146 -#!/bin/bash
147 -#SBATCH --time 0-01:00:00
148 -#SBATCH --nodes 1
149 -#SBATCH --partition all,ps
150 -#SBATCH --array 1-80
151 -#SBATCH --mem 250GB
152 -#SBATCH --job-name ExampleScript
153 -
154 -
155 -source /etc/profile.d/modules.sh
156 -echo "SLURM_JOB_ID $SLURM_JOB_ID"
157 -echo "SLURM_ARRAY_JOB_ID $SLURM_ARRAY_JOB_ID"
158 -echo "SLURM_ARRAY_TASK_ID $SLURM_ARRAY_TASK_ID"
159 -echo "SLURM_ARRAY_TASK_COUNT $SLURM_ARRAY_TASK_COUNT"
160 -echo "SLURM_ARRAY_TASK_MAX $SLURM_ARRAY_TASK_MAX"
161 -echo "SLURM_ARRAY_TASK_MIN $SLURM_ARRAY_TASK_MIN"
162 -
163 -module load maxwell gcc/8.2
164 -
165 -.local/bin/ipython3 --pylab=qt5 PathToYourScript/Script.py $SLURM_ARRAY_TASK_ID
166 -
167 -exit
168 -
169 -
170 -{{/code}}
171 -
172 172  \\
173 173  
174 -To run this use
56 +You will get a node for 6 hours, you can also choose longer or shorter times.
175 175  
176 -{{code}}
177 -sbatch ./your_script.sh
178 -{{/code}}
58 +It can take some time before you get a node, then it will tell you which node is reserved for you. (Example: max-exfl069)
179 179  
180 180  \\
181 181  
182 -=== {{id name="00-HowtologintoMaxwell-Viewingyouallocations"/}}Viewing you allocations ===
62 +Now you can  **login via ssh** on this node:
183 183  
184 -To view your pending or running allocations you can use:
64 +(% class="code" %)
65 +(((
66 +ssh max-exfl069
67 +)))
185 185  
186 -{{code}}
187 -squeue -u <username>
69 +Enter your password.
188 188  
189 -or
190 -
191 -my-jobs
192 -{{/code}}
193 -
194 194  \\
195 195  
196 -=== {{id name="00-HowtologintoMaxwell-Whatisrealisticintermsofresources"/}}What is realistic in terms of resources ===
73 +EXAMPLE:
197 197  
198 -To be fair, you will not get 100 nodes every time you want them. Especially during a user run, the machines are often quite busy. But if you design your scripts to be tolerant to sudden cancellation, it is still worth trying if you profit from massive parallelization.
75 +[[image:attach:image2021-4-27_13-52-11.png||height="125"]]
199 199  
200 -If you want to do some small processing, use one of the psx nodes. This should work most of the time.
77 +\\
201 201  
202 202  \\
203 203  
204 -== {{id name="00-HowtologintoMaxwell-GrantingDataAccesstootherBeamtimes"/}}Granting Data Access to other Beamtimes ==
81 +Now you are on a different node 🙂️.
205 205  
206 -If you have to add other users to a past beamtime, this can be done via the gamma-portal. After adding the accounts, these people have to make sure to log off from **all **FastX sessions, etc. to update the permissions.
83 +You can also start another terminal e.g. if you want to 
207 207  
208 -\\
85 +And
209 209  
210 -\\
87 +[[image:attach:image2021-4-27_13-53-35.png||height="71"]]
211 211  
212 212  \\
90 +
91 +1. [[image:attach:image2021-4-27_13-51-12.png||thumbnail="true" height="250"]]
Confluence.Code.ConfluencePageClass[0]
Id
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1 -305838808
1 +204941686
Title
... ... @@ -1,1 +1,1 @@
1 -00 - How to login to Maxwell
1 +Reconstruction Guideline
URL
... ... @@ -1,1 +1,1 @@
1 -https://confluence.desy.de/spaces/P5I/pages/305838808/00 - How to login to Maxwell
1 +https://confluence.desy.de/spaces/P5I/pages/204941686/Reconstruction Guideline