Re: [Boost-users] [filesystem] problem: is_regular_file and deduplified files (reparse+sparse)

FYI, I followed the blog article, then once the machine was "running" I clicked Connect at the bottom. That gave me an .rdp file which in theory I could use with rdesktop, but it uses a DNS name that was only just created, so that didn't work. When you click the name of the server in the list, it shows the public IP on the right.. and the port then you can do this $ rdesktop that.ip.addr:port But only if you have the latest rdesktop AND you have set up kerberos something-something. Instead I found a windows computer and used remote desktop from there. --- Once inside, in the "Server Manager --> Dashboard" window on the screen, click "Add Roles" then go next next until "Server Roles" expand "File and Storage services" , "File and iSCSI" , and tick "Data Deduplication" Then next next etc and Install. Wait a bit... and its done. http://www.techrepublic.com/blog/data-center/configuring-windows-server-8-de... --- Continuing on that webpage... Time to enable dedup. There is a temp disk D: so lets enable there. Method 1... I did this and then went to method 2... Start PowerShell, type: "Enable-DedupVolume D:" Method 2... in that same Dashboard, hit the 4th button (File and Storage Services) Then Volumes --> Disks click Volume 1 at the top, and then right click D: at the bottom --> Configure Dedup. To try and accelerate this puppy, I set the "age to dedup" to 0 days. http://www.techrepublic.com/blog/data-center/windows-server-2012-deduplicati... --- Time to make something to dedup. We'll just duplicate the warning.txt file that exists on D: In powershell: PS> D: PS> $file = Get-Content DATALOSS_WARNING_README.txt Then, do these 2 commands a bunch of times until "big.txt" gets to say 6MB PS> Add-Content big.txt $file PS> $file = Get-Content big.txt Then use windows explorer (or other) to make a dozen copies of big.txt Copy c:\windows\explorer.exe to D: to give it something to dedup Go to D: and then copy-paste explorer.exe a dozen times. In PowerShell, type: PS> Update-DedupStatus -Volume D: PS> Start-DedupStatus -Type Optimization -Volume D: and then wait for it to finish. you can track its progress with: PS> Get-DedupJob PS> Get-DedupStatus -Volume D: --- So, once its deduped, you check. PS> FSUTIL REPARSEPOINT QUERY big.txt you should see that its a reparse point with that 0x800etc0013 code. Copy-paste big.txt to big2.txt and check it with the query, and it should tell you big2 is NOT a reparse point. NOW TO TEST ! ---- On 23 July 2015 at 13:57, Paul Harris wrote:

Hi Niall, you can use the Azure to test this sort of thing... I think. I'm trying it out now.

http://blogs.technet.com/b/tommypatterson/p/azureservertrial.aspx

On 23 July 2015 at 09:54, Niall Douglas wrote:

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On 23 Jul 2015 at 8:56, Paul Harris wrote:

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With this server comes the new "dedup" feature, that can automatically deduplify files. This happens on a schedule, eg 2am saturday. So suddenly we are getting messages of failures of software from all over the place, due to fs::is_regular_file()

Deduped files have the REPARSE and SPARSE flag set. On the command line, you can run FSUTIL REPARSEPOINT QUERY

and the "Reparse Tag Value" is 0x80000013

Which is a relatively new flag known as IO_REPARSE_TAG_DEDUP

https://msdn.microsoft.com/en-us/library/windows/desktop/aa365740%28v=vs.85%...

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These files act as normal files, you can fopen and fread them, so I

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they should be treated almost like symlink by boost... perhaps not quite a symlink because I assume the "lstat" link properties are identical to

assume the

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file's stat properties.

Typically, I iterate over directories and only process files if fs::is_regular_file(filename) is true.

I wrote some code to check what the properties were on these files, and its not any of the possible enums detected by file_status::type().

ideas?

Proposed Boost.AFIO doesn't support IO_REPARSE_TAG_DEDUP because I have no access to any system to test the support upon.

However, if AFIO were to support IO_REPARSE_TAG_DEDUP, it would treat it identically to a symlink/junction point.

I'd suggest Boost.Filesystem do the same, and treat pseudo-symlinks as symlinks. That probably means adding full symlink support for Filesystem on Windows. Here are some links to example implementation code:

Reading a symlink target: https://github.com/BoostGSoC13/boost.afio/blob/master/include/boost/af io/v2/detail/impl/afio_iocp.ipp#L511 https://github.com/BoostGSoC13/boost.afio/blob/master/include/boost/afio/v2/...

Writing a symlink: https://github.com/BoostGSoC13/boost.afio/blob/master/include/boost/af io/v2/detail/impl/afio_iocp.ipp#L848 https://github.com/BoostGSoC13/boost.afio/blob/master/include/boost/afio/v2/...

Obviously best not allow rewriting a pseudo-symlink like IO_REPARSE_TAG_DEDUP, make it read only.

Niall

-- ned Productions Limited Consulting http://www.nedproductions.biz/ http://ie.linkedin.com/in/nialldouglas/

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