Difference between revisions of "Partitioning Cache Data"

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(New Node Reshuffle)
(Title Distribution)
Line 270: Line 270:
 
  }
 
  }
 
}</nowiki>
 
}</nowiki>
 +
 +
A resultant table set could look like the following:
 +
 +
<nowiki>peer_id  count(*)  % burden
 +
ADAH   499   55%
 +
AUB   549   61%
 +
BPL   520   57%
 +
SHC   504   56%
 +
SHC1   490   54%
 +
TROY   492   54%
 +
UAB   532   59%
 +
UAT   852   94%
 +
UAT1   482   53%
 +
UNA   510   56%
 +
 +
905 Titles</nowiki>
 +
  
 
=== New Node Reshuffle ===
 
=== New Node Reshuffle ===
Line 295: Line 312:
 
   {
 
   {
 
     _connect.Command.Parameters.Clear();
 
     _connect.Command.Parameters.Clear();
     _connect.Command.CommandText = @"UPDATE `adpn_peer_titles` SET `peer_id` = ?
+
     _connect.Command.CommandText = @"
WHERE `peer_id` = (SELECT `peer_id` FROM `adpn_peer_titles` WHERE `au_id` = ? and `peer_id` != ? ORDER BY RAND() LIMIT 1)";
+
UPDATE `adpn_peer_titles` AS `a`,
 +
(SELECT  `b`.`peer_id`  
 +
FROM `adpn_peer_titles` AS `b`
 +
WHERE `b`.`au_id` = ? and `b`.`peer_id` != ?
 +
ORDER BY RAND() LIMIT 1) AS `b`
 +
SET `a`.`peer_id` = ?
 +
WHERE `a`.`peer_id` = `b`.`peer_id`
 +
AND `a`.`au_id` = ? ";
 +
 
 +
    _connect.Command.Parameters.AddWithValue("?", _row["au_id"].ToString());
 +
    _connect.Command.Parameters.AddWithValue("?", _row["au_pub_id"].ToString());
 
     _connect.Command.Parameters.AddWithValue("?", _peer);
 
     _connect.Command.Parameters.AddWithValue("?", _peer);
 
     _connect.Command.Parameters.AddWithValue("?", _row["au_id"].ToString());
 
     _connect.Command.Parameters.AddWithValue("?", _row["au_id"].ToString());
    _connect.Command.Parameters.AddWithValue("?", _row["au_pub_id"].ToString());
 
 
     _connect.Command.ExecuteNonQuery();
 
     _connect.Command.ExecuteNonQuery();
 
   }
 
   }
 
  }
 
  }
 
}</nowiki>
 
}</nowiki>
 +
 +
 +
Using the original distribution and reshuffling for a new node resulted in :
 +
 +
<nowiki>peer_id  count(*)  % burden
 +
ADAH   456    50%
 +
AUB   492    54%
 +
BPL   467    52%
 +
SHC   456   50%
 +
SHC1   438   48%
 +
TROY    445   49%
 +
UAB   466   51%
 +
UAT   845   93%
 +
UAT1   441   49%
 +
UNA   467   52%
 +
BPL1   457   50%
 +
 +
905 titles
 +
</nowiki>
  
 
=== Dead Node Reshuffle ===
 
=== Dead Node Reshuffle ===

Revision as of 14:58, 7 August 2013

Why Partition

Partitioned Cost Reductions

Quorum in the network is 3. (This is down from the previous value of 4... find out why).

Any sort of partitioning strategy would need to be implemented at the titledb.xml level. Title AUs can be assigned to peers centrally, and each peer should receive a custom titledb.xml file. If LOCKSS is unwilling to support that then there is alternative using local parameters.

org.lockss.titleDbs = http://bpldb.bplonline.org/etc/adpn/titledb-local.xml

Implementing a 1 + 6 partitioning strategy can save 12% on average for each network node. 1 + 6 indicates AU owner + 6 additional network nodes. Adding 2 additional nodes to the network can decrease per node storage by an average of 30%. Adding 4 additional nodes and partitioning cache data can save per node storage on average of 41%. This means we could store up to 18 TB of data on 10.6 TB nodes.

Implementing a 1 + 5 which is 6 discrete nodes in the network (double quorum), base storage decrease is 25% with no additional nodes. 1 + 5 with 4 additional nodes achieves a staggering 50% on average per node storage reduction.

All nodes (default configuration)

			
au_host	AUCount	ContentSize in TB	DiskCost in TB
ADAH	778	5.11	5.13
AUB	778	5.11	5.13
BPL	778	5.11	5.13
SHC	778	5.11	5.13
TROY	778	5.11	5.13
UAB	778	5.11	5.13
UAT	778	5.11	5.13
UNA	778	5.11	5.13
		40.88	41.04

Does not include vacated publisher AUs (which is between 500 and 600 GB).

1 + 6 no additional nodes

au_host	AUCount	ContentSize	DiskCost	count	size	cost
ADAH	667	4.60	4.62		-14.27%	-9.99%	-9.97%
AUB	676	3.83	3.85		-13.11%	-25.00%	-24.94%
BPL	669	4.49	4.51		-14.01%	-12.19%	-12.15%
SHC	666	4.48	4.49		-14.40%	-12.41%	-12.41%
TROY	666	4.29	4.30		-14.40%	-16.13%	-16.09%
UAB	667	4.58	4.60		-14.27%	-10.29%	-10.26%
UAT	767	5.06	5.09		-1.41%	-0.89%	-0.86%
UNA	667	4.43	4.45		-14.27%	-13.27%	-13.23%
		35.76	35.91			-12.52%	-12.49%

1 + 6 with 2 additional nodes

au_host	AUCount	ContentSize	DiskCost	count	size	cost
ADAH	519	3.93	3.95		-33.29%	-23.00%	-22.98%
AUB	540	3.21	3.23		-30.59%	-37.15%	-37.09%
BPL	522	3.09	3.11		-32.90%	-39.49%	-39.44%
SHC	519	3.22	3.23		-33.29%	-36.97%	-36.96%
TROY	519	3.26	3.28		-33.29%	-36.15%	-36.09%
UAB	519	3.02	3.03		-33.29%	-40.93%	-40.89%
UAT	751	4.89	4.91		-3.47%	-4.40%	-4.38%
UNA	519	3.26	3.28		-33.29%	-36.15%	-36.09%
ADAH2	518	3.94	3.95				
BPL2	519	3.94	3.95				
		35.76	35.91		-12.52%	-12.49%

1 + 6 with 4 additional nodes

au_host	AUCount	ContentSize in TB	DiskCost in TB		
ADAH	503	2.60	2.61	-35.35%	-49.11%
AUB	425	3.16	3.17	-45.37%	-38.13%
BPL	405	2.47	2.48	-47.94%	-51.57%
SHC	408	2.83	2.84	-47.56%	-44.66%
TROY	401	3.34	3.35	-48.46%	-34.68%
UAB	413	2.50	2.51	-46.92%	-51.13%
UAT	740	4.79	4.81	-4.88%	-6.23%
UNA	357	2.97	2.98	-54.11%	-41.96%
ADAH2	407	2.52	2.54		
AUB2	501	3.25	3.26		
BPL2	457	2.86	2.87		
UAT2	428	2.48	2.49		
		35.76	35.91	-41.32%	-39.68%

1 + 5 with no additional nodes

							
au_host	AUCount	ContentSize in TB	DiskCost in TB				
ADAH	581	3.83	3.85	-25.32%	-24.87%		
AUB	539	3.97	3.99	-30.72%	-22.12%		
BPL	537	3.72	3.73	-30.98%	-27.13%		
SHC	590	3.36	3.38	-24.16%	-34.07%		
TROY	555	3.79	3.81	-28.66%	-25.71%		
UAB	572	3.68	3.70	-26.48%	-27.87%		
UAT	757	4.92	4.93	-2.70%	-3.68%		
UNA	536	3.34	3.35	-31.11%	-34.56%		
		30.65	30.78	-25.02%	-25.00%

1 + 5 with 4 additional nodes

au_host	AUCount	ContentSize in TB	DiskCost in TB		
ADAH	395	1.95	1.96	-49.23%	-61.80%
AUB	349	2.90	2.91	-55.14%	-43.30%
BPL	463	2.77	2.78	-40.49%	-45.74%
SHC	350	2.94	2.95	-55.01%	-42.46%
TROY	327	1.83	1.84	-57.97%	-64.18%
UAB	331	2.10	2.11	-57.46%	-58.88%
UAT	736	4.85	4.87	-5.40%	-5.02%
UNA	312	2.37	2.38	-59.90%	-53.55%
ADAH2	332	2.06	2.07		
AUB2	328	2.52	2.53		
BPL2	367	2.53	2.54		
UAT2	377	1.83	1.84		
		30.65	30.78	-47.57%	-46.87%

Distribution Algorithms

TBD...

Sample data was run using a static array of nodes, "randomized" with a Fisher-Yates shuffle, and least used node put in first array position.

string[] _nodes = { "ADAH", "AUB", "UAT", "UAB", "BPL", "UNA", "TROY", "SHC" };
Shuffle(_nodes); // Fisher-Yates Shuffle
            
//string _leastUsedNode = GetLeastUsedNodeByAUCount();
//string _leastUsedNode = GetLeastUsedNodeByContentSize();
string _leastUsedNode = GetLeastUsedNodeByDiskCost();

// put at beginning of array
Swap(_nodes, _leastUsedNode);

int _counter = 0;
// insert 6 5
foreach (string _node in _nodes)
{
 if (_counter == 5) break;
 if (_node.Equals(_row["au_owner"].ToString()))  continue; 

 // process
 counter++;
}

Storage Calculator

http://www.ibeast.com/content/tools/RaidCalc/RaidCalc.asp RAID Calculator

8 Disks * 3072 GB + RAID 5 = 20027.16 GB

Partition Implementation

Title List

The title list is the most crucial component for any partitioning. With close to 1000 AUs management of partition responsibilities would be cumbersome at the node level.

<lockss-config>
 <property name="org.lockss.titleSet">
  <property name="Birmingham Public Library">
   <property name="name" value="All Birmingham Public Library AUs" />
   <property name="class" value="xpath" />
   <property name="xpath" value="[attributes/publisher='Birmingham Public Library']" />
  </property>
 </property> 
 <property name="org.lockss.title">
  <property name="BirminghamPublicLibraryBasePluginBirminghamPublicLibraryCartographyCollectionMaps000400000599">
   <property name="attributes.publisher" value="Birmingham Public Library" />
   <property name="journalTitle" value="Birmingham Public Library Cartography Collection" />
   <property name="type" value="journal" />
   <property name="title" value="Birmingham Public Library Cartography Collection: Maps (000400-000599)" />
   <property name="plugin" value="org.bplonline.adpn.BirminghamPublicLibraryBasePlugin" />
   <property name="param.1">
    <property name="key" value="base_url" />
    <property name="value" value="http://bpldb.bplonline.org/adpn/load/" />
   </property>
   <property name="param.2">
    <property name="key" value="group" />
    <property name="value" value="Cartography" />
   </property>
   <property name="param.3">
    <property name="key" value="collection" />
    <property name="value" value="000400-000599" />
   </property>
  </property>
 </property>
</lockss-config>


Comprehending LOCKSS Title List

Nested same name elements with different levels of nesting depth causes some difficulty in comprehension using standard tools. Standard deserialization techniques won't work because group 1 property element collection (org.lockss.titleSet) has different depth than group 2 property element collection (org.lockss.title).

protected void DeserializeXml() {
 using (FileStream _f = new FileStream(Server.MapPath(@"titledb.xml"), FileMode.Open, FileAccess.Read))
 {
  XmlReaderSettings _sets = new XmlReaderSettings();
  _sets.IgnoreWhitespace = true;
  _sets.ProhibitDtd = false;

  XmlReader _xml = XmlReader.Create(_f, _sets);
  XmlSerializer _xs = new XmlSerializer(typeof(LockssTitleDb));
  LockssTitleDb _titles = (LockssTitleDb)_xs.Deserialize(_xml);
 
  for (int i = 0; i < _titles.LockssTitleSet.Length; i++)
  {
    if (i % 2 == 0)
    {
      // first group property (has attribute name=org.lockss.titleSet)
      // titleSet displays publisher detail
      // this assumes group of 2 for each publisher and AU list
    } 
    else 
    {
      // second group property (has attribute name=org.lockss.title)
      // each iteration is a new AU for group 1 publisher
      for (int j = 0; j < _titles.LockssTitleSet[i].ChildNodes.Count; j++)
      {
        // property  name = normalized AU string
        // outer AU definition
        foreach (XmlNode _node in _titles.LockssTitleSet[i].ChildNodes[j].ChildNodes)
        {
          // loop through property tags          
        }
      }
    }
  }
  _f.close();
 }
...
[XmlRoot("lockss-config")]
public class LockssTitleDb 
{
    // cannot create a single interface for all nesting depths with a single name
    [XmlAnyElement()]
    public XmlElement[] LockssTitleSet;
}

Local Data Store

http://bpldb.bplonline.org/images/adpn/datastore.png

XML Generation

ExpertConfig option org.lockss.titlesDb does not examine content type. It only looks at the URL ending and string matches .xml, else it assumes it is a .txt configuration file. See BaseConfigFile.java constructor.

Title Distribution

Base Distribution

Using the local data store, au_ids are auto-incremented. After the initial distribution, new AU releases can be isolated by selecting from last known Id. Row timestamp could also be used.

string[] _peers = GetPeerArray();
foreach (DataRow _row in _titles.Rows)
{
 Shuffle(_peers);

 int _counter = 0;
 bool _isPeer = IsPeer(_row["au_pub_id"].ToString());
 int _maxCount = _isPeer ? 5 : 6; 
 // not every publisher is a peer

 // insert 6 5
 foreach (string _peer in _peers)
 {
  if (_counter == _maxCount) break;
  if (_peer.Equals(_row["au_pub_id"].ToString())) continue;

  _connect.Command.Parameters.Clear();
  _connect.Command.CommandText = "INSERT INTO `adpn_peer_titles` (`peer_id`, `au_id`) VALUES (?,?)";
  _connect.Command.Parameters.AddWithValue("?", _peer);
  _connect.Command.Parameters.AddWithValue("?", _row["au_id"].ToString());
  _connect.Command.ExecuteNonQuery();
  _counter++;
 }

 if (_isPeer)
 {
  // insert 1
  _connect.Command.Parameters.Clear();
  _connect.Command.CommandText = "INSERT INTO `adpn_peer_titles` (`peer_id`, `au_id`) VALUES (?,?)";
  _connect.Command.Parameters.AddWithValue("?", _row["au_pub_id"].ToString());
  _connect.Command.Parameters.AddWithValue("?", _row["au_id"].ToString());
  _connect.Command.ExecuteNonQuery();
 }
}

A resultant table set could look like the following:

peer_id  count(*)  % burden
ADAH	  499	  55%
AUB	  549	  61%
BPL	  520	  57%
SHC	  504	  56%
SHC1	  490	  54%
TROY	  492	  54%
UAB	  532	  59%
UAT	  852	  94%
UAT1	  482	  53%
UNA	  510	  56%
		
905	Titles	


New Node Reshuffle

The original distribution algorithm can be used with a slight modification, only update rows in the adpn_peer_titles table when new node is up after shuffle. Assuming the new node is not considered a AU owner for existing AUs. Will reduce current AU burden on non-owner peers by maintaining a consistent node count per AU but replacing extant with new node.

string[] _peers = GetPeerArray();
foreach (DataRow _row in _titles.Rows)
{
 Shuffle(_peers);

 int _counter = 0;
 bool _isPeer = IsPeer(_row["au_pub_id"].ToString());
 int _maxCount = _isPeer ? 5 : 6; 
 // not every publisher is a peer

 // insert 6 5
 foreach (string _peer in _peers)
 {
  if (_counter == _maxCount) break;
  if (_peer.Equals(_row["au_pub_id"].ToString())) continue;

  // ONLY modify existing AU map when new node is up 
  if (_peer.Equals(newNodePeerId))
  {
    _connect.Command.Parameters.Clear();
    _connect.Command.CommandText = @"
UPDATE `adpn_peer_titles` AS `a`, 
 (SELECT  `b`.`peer_id` 
 FROM `adpn_peer_titles` AS `b` 
 WHERE  `b`.`au_id` = ? and  `b`.`peer_id` != ?
 ORDER BY RAND() LIMIT 1) AS `b` 
SET `a`.`peer_id` = ?
WHERE `a`.`peer_id` = `b`.`peer_id`
AND `a`.`au_id` = ? ";

    _connect.Command.Parameters.AddWithValue("?", _row["au_id"].ToString());
    _connect.Command.Parameters.AddWithValue("?", _row["au_pub_id"].ToString());
    _connect.Command.Parameters.AddWithValue("?", _peer);
    _connect.Command.Parameters.AddWithValue("?", _row["au_id"].ToString());
    _connect.Command.ExecuteNonQuery();
  }
 }
}


Using the original distribution and reshuffling for a new node resulted in :

peer_id  count(*)  % burden
ADAH	  456     50%
AUB	  492  	  54%
BPL	  467     52%
SHC	  456	  50%
SHC1	  438	  48%
TROY  	  445	  49%
UAB	  466	  51%
UAT	  845	  93%
UAT1	  441	  49%
UNA	  467	  52%
BPL1	  457	  50%

905 titles 

Dead Node Reshuffle

When a node is no longer a part of the network:

  1. Delete peer_id from apdn_peer_titles
  2. Select a list of peer_ids and au_ids where count is less than maxcount
  3. Insert a shuffled peer id where not in peer_ids select list