Yes I know, 6.0.5 - we cannot upgrade. A question of politics/finance. It is not a popular option to scale up/out either.

The app has been running on Azure as a single instance on S2 really well for years. No load balancing. It's a large site but not that many users - no more than 300 users at any one time. There are many, many documents and pdfs on the site.

For the past month we have experienced frequent site outages. CPU use has been spiking wildly and the site slows to a crawl, >30s response times.

Amongst (many!) other things, we're getting macros failing because of Lucene file reading errors. My feeling is that this is related to the Azure latency as describe in Sebastiaan's article, and that we'd need to move to >7.2.8 to solve it.

Is my thinking correct? Or should I be looking more at the sheer amount of docs in the media folders?

Is there anything else we should look at/try?

Error from Umbraco log:

2017-04-28 12:05:27,034 [12] WARN  Umbraco.Web.Routing.NiceUrlProvider - [Thread 111] Couldn't find any page with nodeId=1442. This is most likely caused by the page not being published.
2017-04-28 12:05:27,190 [12] WARN  Umbraco.Web.Routing.NiceUrlProvider - [Thread 111] Couldn't find any page with nodeId=1442. This is most likely caused by the page not being published.
2017-04-28 12:05:37,784 [12] WARN  umbraco.macro - [Thread 113] Error loading Partial View (file: ~/Views/MacroPartials/UsefulLinks.cshtml). Exception: System.Threading.ThreadAbortException: Thread was being aborted.
   at Microsoft.Win32.Win32Native.CreateFile(String lpFileName, Int32 dwDesiredAccess, FileShare dwShareMode, SECURITY_ATTRIBUTES securityAttrs, FileMode dwCreationDisposition, Int32 dwFlagsAndAttributes, IntPtr hTemplateFile)
   at Microsoft.Win32.Win32Native.SafeCreateFile(String lpFileName, Int32 dwDesiredAccess, FileShare dwShareMode, SECURITY_ATTRIBUTES securityAttrs, FileMode dwCreationDisposition, Int32 dwFlagsAndAttributes, IntPtr hTemplateFile)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
   at Lucene.Net.Store.SimpleFSDirectory.OpenInput(String name, Int32 bufferSize)
   at Lucene.Net.Index.SegmentInfos.FindSegmentsFile.Run(IndexCommit commit)
   at Lucene.Net.Index.SegmentInfos.Read(Directory directory)
   at Lucene.Net.Index.SegmentInfos.ReadCurrentVersion(Directory directory)
   at Lucene.Net.Index.DirectoryReader.IsCurrent()
   at Examine.LuceneEngine.LuceneExtensions.GetReaderStatus(IndexReader reader)
   at Examine.LuceneEngine.Providers.LuceneSearcher.ValidateSearcher(Boolean forceReopen)
   at Examine.LuceneEngine.Providers.LuceneSearcher.GetSearchFields()
   at UmbracoExamine.UmbracoExamineSearcher.GetSearchFields()
   at Examine.LuceneEngine.Providers.BaseLuceneSearcher.CreateSearchCriteria(String type, BooleanOperation defaultOperation)
   at UmbracoExamine.UmbracoExamineSearcher.CreateSearchCriteria(String type, BooleanOperation defaultOperation)
   at Umbraco.Web.DefaultPublishedMediaStore.GetUmbracoMedia(Int32 id)
   at Umbraco.Web.UmbracoHelper.DocumentById(Int32 id, IPublishedStore store, Object ifNotFound)
   at Umbraco.Web.UmbracoHelper.Media(String id)
   at ASP._Page_Views_MacroPartials_UsefulLinks_cshtml.Execute() in d:\home\site\wwwroot\Views\MacroPartials\UsefulLinks.cshtml:line 22
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at Umbraco.Web.Mvc.ControllerExtensions.RenderViewResultAsString(ControllerBase controller, ViewResultBase viewResult)
   at Umbraco.Web.Macros.PartialViewMacroEngine.Execute(MacroModel macro, INode currentPage)
   at umbraco.macro.LoadPartialViewMacro(MacroModel macro)
   at umbraco.macro.renderMacro(Hashtable pageElements, Int32 pageId)