{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "eada1107-1957-4868-b9a2-326ce0663b43",
   "metadata": {},
   "source": [
    "# Accessing files in different storage locations"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "f27d9e7e-5f1b-4630-843a-3025741b690c",
   "metadata": {},
   "source": [
    "In this demo, we demonstrate how data can be accessed from different storage spaces available to a Purdue Analysis Facility user. Copies of the same ROOT file have been placed in different storage locations, in this example they are accessed via `uproot.open()`."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "76288510-3239-4606-89b2-47156171644c",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "import uproot\n",
    "import time\n",
    "\n",
    "def test_file_access(path, filename):\n",
    "    '''\n",
    "    This function opens a NanoAOD file at a given path\n",
    "    and prints the pT of the first muon found in that file,\n",
    "    as well as the time taken to access the file.\n",
    "    '''\n",
    "\n",
    "    print(f\"Accessing file at {path}{filename}\")\n",
    "    start = time.time()\n",
    "    with uproot.open(path+filename)[\"Events\"] as file:\n",
    "        pt = file[\"Muon_pt\"].array()[0][0]\n",
    "        print(\"First muon pT: \", round(pt, 2), \"GeV\")\n",
    "\n",
    "    dt = round(time.time()-start, 2)\n",
    "    print(f\"Time elapsed: {dt}s.\")\n",
    "    print()\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "865c3159-8061-4123-b80f-c5c3945f300f",
   "metadata": {
    "tags": []
   },
   "source": [
    "### 0. Local files"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "c187c93a-8479-4f77-a1ea-5c5306b79108",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Accessing file at ./data/test_nanoaod.root\n",
      "First muon pT:  82.55 GeV\n",
      "Time elapsed: 3.91s.\n",
      "\n"
     ]
    }
   ],
   "source": [
    "test_file_access(\"./data/\", \"test_nanoaod.root\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "050e19bc-955e-4a75-a4e4-c92e81a0f09c",
   "metadata": {
    "tags": []
   },
   "source": [
    "### 1. Purdue Depot\n",
    "The Purdue Depot storage is writeable for Purdue users, but read-only for external users."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "a1d9210a-18fd-4312-b7b1-38d6f6d1fe06",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Accessing file at /depot/cms/hmm/test_nanoaod_depot.root\n",
      "First muon pT:  82.55 GeV\n",
      "Time elapsed: 0.87s.\n",
      "\n",
      "Accessing file at ~/depot/hmm/test_nanoaod_depot.root\n",
      "First muon pT:  82.55 GeV\n",
      "Time elapsed: 0.71s.\n",
      "\n"
     ]
    }
   ],
   "source": [
    "# Choice of two paths - the mount point and the symlink in home directory\n",
    "# (the latter is convenient for access via the file browser).\n",
    "\n",
    "filename = \"test_nanoaod_depot.root\"\n",
    "test_file_access(\"/depot/cms/hmm/\", filename)\n",
    "test_file_access(\"~/depot/hmm/\", filename)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "7b3e85b1-65b3-490e-93cb-5e7d8be5cb12",
   "metadata": {
    "tags": []
   },
   "source": [
    "### 2. Purdue EOS\n",
    "Purdue EOS storage is mounted as read-only FS; however, Purdue users can write to their EOS directories using `gfal` commands [(see instrictions here)](https://www.physics.purdue.edu/Tier2/user-info/tutorials/dfs_commands.php)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "ac050d04-e2ad-431f-a216-1ff943fa92a0",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Accessing file at /eos/purdue/store/user/dkondrat/test_nanoaod_eos_purdue.root\n",
      "First muon pT:  82.55 GeV\n",
      "Time elapsed: 0.82s.\n",
      "\n",
      "Accessing file at ~/eos-purdue/store/user/dkondrat/test_nanoaod_eos_purdue.root\n",
      "First muon pT:  82.55 GeV\n",
      "Time elapsed: 0.79s.\n",
      "\n"
     ]
    }
   ],
   "source": [
    "# Choice of two paths - the mount point and the symlink in home directory\n",
    "# (the latter is convenient for access via the file browser).\n",
    "\n",
    "filename = \"test_nanoaod_eos_purdue.root\"\n",
    "test_file_access(\"/eos/purdue/store/user/dkondrat/\", filename)\n",
    "test_file_access(\"~/eos-purdue/store/user/dkondrat/\", filename)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "6d7241ef-7e41-45c0-8b21-c4c53f70a8e4",
   "metadata": {
    "tags": []
   },
   "source": [
    "### 3. CERN EOS (CERNBox)\n",
    "\n",
    "<div class=\"alert alert-warning\">\n",
    "Warning\n",
    "\n",
    "The following cell must be modified, since each user only gets access to their own CERNBox directory.\n",
    "To enable access to your CERNBox, run command `eos-connect` in terminal.\n",
    "</div>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "66e36f07-1881-4201-b767-93c73d41760a",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Accessing file at /eos/cern/home-d/dkondrat/test_nanoaod_eos_cern.root\n",
      "First muon pT:  82.55 GeV\n",
      "Time elapsed: 5.31s.\n",
      "\n",
      "Accessing file at ~/eos-cern/test_nanoaod_eos_cern.root\n",
      "First muon pT:  82.55 GeV\n",
      "Time elapsed: 0.77s.\n",
      "\n"
     ]
    }
   ],
   "source": [
    "# Choice of two paths - the mount point and the symlink in home directory\n",
    "# (the latter is convenient for access via the file browser).\n",
    "\n",
    "filename = \"test_nanoaod_eos_cern.root\"\n",
    "test_file_access(\"/eos/cern/home-d/dkondrat/\", filename)\n",
    "test_file_access(\"~/eos-cern/\", filename)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "1ec8737d-d9c4-4179-9328-781a789a4c7a",
   "metadata": {
    "tags": []
   },
   "source": [
    "### 4. XRootD\n",
    "Before using XRootD, initialize the VOMS proxy in terminal (`voms-proxy-init --voms cms`)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "5eca0546-a33b-44e9-9e62-315b3c5d4d7e",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Accessing file at root://eos.cms.rcac.purdue.edu//store/user/dkondrat/test_nanoaod_eos_purdue.root\n",
      "First muon pT:  82.55 GeV\n",
      "Time elapsed: 2.03s.\n",
      "\n"
     ]
    }
   ],
   "source": [
    "test_file_access(\"root://eos.cms.rcac.purdue.edu//store/user/dkondrat/\", \"test_nanoaod_eos_purdue.root\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b5c7c550-906b-479f-baa6-c7bd1312293d",
   "metadata": {
    "tags": []
   },
   "source": [
    "### 5. CVMFS"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "86e1c2f2-cd73-46aa-8b46-1fe1a643cab1",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "/cvmfs/cms.cern.ch/cmsset_default.sh\n"
     ]
    }
   ],
   "source": [
    "!ls /cvmfs/cms.cern.ch/cmsset_default.sh"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "2a98d156-382f-494a-a07c-ee3daf3706ff",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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