Can an unstable PC corrupt files stored on a server?

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Can an unstable PC corrupt files stored on a server?

Postposted on Thu Jan 24, 2013 9:42 pm

I'm in the process of setting up a gaming HTPC and am facing some stability issues that I believe are related to the GTX 660 graphics card. Occasionally the machine will crash and display a BSOD right in the middle of a movie. All of my files are stored on an older Celeron 430 based file server. Can the stop errors corrupt files stored on the server?
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Thu Jan 24, 2013 10:30 pm

Assuming you're just watching movies (i.e. the unstable PC is not writing to any files on the server), the odds of files on the server getting corrupted is very low. Depending on the exact nature of the instability I suppose it is theoretically *possible*, but you've probably got better odds of winning the lottery than of seeing file corruption on the server from this.

The one exception would be if the instability is actually malware-related, in which case all bets are off.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 12:35 am

Or, perhaps if the media player is in the process of updating metadata.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 2:29 am

I know for a fact that an open MS Access DB can easily be corrupted by sudden network/power outage. Even though the client is not writing to the database and just keeps it open. Potentially the same could be applied to other types of files that opened across network.

Also opportunistic locking can cause corruption if file server OS is any of the folowing: Vista, Windows 7, Windows 2008. There is a registry key that needs to be set to disable it.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
‐ add a DWORD (32‐bit) key with a value of zero
‐ Name the Key = "SMB2"
‐ Reboot the computer

Test it by disconnecting network cable during playback and see if it corrupts the file. What is the error message if you attempt to open/play a corrupt file? Did you notice any corruptions when computer did NOT crash with BSOD?
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 3:23 am

Ethyriel wrote:Or, perhaps if the media player is in the process of updating metadata.

I would hope that the player would not be touching the metadata unless you've explicitly edited it! For it to do otherwise would arguably be a bug.

michael_d wrote:I know for a fact that an open MS Access DB can easily be corrupted by sudden network/power outage. Even though the client is not writing to the database and just keeps it open. Potentially the same could be applied to other types of files that opened across network.

OP specifically mentioned playing movies from the server; I assumed that this was the use case he was worried about. Using an Access database is a very different animal from streaming a movie; since Access is entirely file-based (no server process), record/table locking is done by touching the database file(s) themselves.

michael_d wrote:Also opportunistic locking can cause corruption if file server OS is any of the folowing: Vista, Windows 7, Windows 2008. There is a registry key that needs to be set to disable it.

I was not aware of this issue; but all of the info I've been able to find in a few minutes of Googling seems to indicate that it only affects applications which modify files on the server. Do you have any evidence that it happens even if the client is not modifying the files? If so, then this is a *major* defect in the implementation of op locks!

***

To the OP: I still think the risk is tiny. If you're concerned about any of the above issues, make the share(s) used by the HTPC read-only.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 1:12 pm

The instability seems to be video related. This machine will go all day with the IGP or my HD 5570 test card. It's also stable when I disable the GTX 660's hardware decoder and let the CPU do all of the work. Going to try a few different drivers; if that doesn't work it's RMA time.

just brew it! wrote:To the OP: I still think the risk is tiny. If you're concerned about any of the above issues, make the share(s) used by the HTPC read-only.


I think I'll go ahead and do that, at least for now. Thanks for the idea.

michael_d wrote:Test it by disconnecting network cable during playback and see if it corrupts the file. What is the error message if you attempt to open/play a corrupt file? Did you notice any corruptions when computer did NOT crash with BSOD?


I'm not worried about the sudden loss of network connectivity corrupting the file so much as I'm worried about the unstable PC "accidentally" writing bad data to the server when it loses its mind and crashes. I haven't noticed any corruption yet. Was just wondering if the unstable PC had the potential to corrupt files on the server during the troubleshooting process.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 1:40 pm

What's the power supply? The GTX 660 is pulling more power than the old Radeon, most likely, since the Radeon 5570 doesn't have a 6-pin PCI-e power connector whereas the GTX 660 does. Got a spare PSU hanging around? Depending on the codec, bitrate, resolution etc. it might be more power efficient to let the CPU do the decoding (without respect to quality, where the Geforce may do much better) and therefore not as much stress overall.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 1:56 pm

setaG_lliB wrote:The instability seems to be video related. This machine will go all day with the IGP or my HD 5570 test card. It's also stable when I disable the GTX 660's hardware decoder and let the CPU do all of the work. Going to try a few different drivers; if that doesn't work it's RMA time.

michael_d wrote:Test it by disconnecting network cable during playback and see if it corrupts the file. What is the error message if you attempt to open/play a corrupt file? Did you notice any corruptions when computer did NOT crash with BSOD?


I'm not worried about the sudden loss of network connectivity corrupting the file so much as I'm worried about the unstable PC "accidentally" writing bad data to the server when it loses its mind and crashes. I haven't noticed any corruption yet. Was just wondering if the unstable PC had the potential to corrupt files on the server during the troubleshooting process.


I think there is a potential. I recall we had a client with network/server problems which led to corruption of multiple image files. Software simply would not recognize them as a valid images. There was nothing we could do to fix them. When image file corruption occurred it would alter the file size sometimes down to 1KB, sometimes it would increase image size.

just brew it! wrote:
michael_d wrote:I know for a fact that an open MS Access DB can easily be corrupted by sudden network/power outage. Even though the client is not writing to the database and just keeps it open. Potentially the same could be applied to other types of files that opened across network.

OP specifically mentioned playing movies from the server; I assumed that this was the use case he was worried about. Using an Access database is a very different animal from streaming a movie; since Access is entirely file-based (no server process), record/table locking is done by touching the database file(s) themselves.

michael_d wrote:Also opportunistic locking can cause corruption if file server OS is any of the folowing: Vista, Windows 7, Windows 2008. There is a registry key that needs to be set to disable it.

I was not aware of this issue; but all of the info I've been able to find in a few minutes of Googling seems to indicate that it only affects applications which modify files on the server. Do you have any evidence that it happens even if the client is not modifying the files? If so, then this is a *major* defect in the implementation of op locks!

***

To the OP: I still think the risk is tiny. If you're concerned about any of the above issues, make the share(s) used by the HTPC read-only.


I cannot provide a 100% proof that just keeping a file open across network could lead to corruption because I experienced this issue many times on networks with 5 to 20 computers. Difficult to say which one was the culprit. As far as op locks is concerned, I personally experienced that disabling it would prevent MS Access DB corruptions.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 2:12 pm

Access is a train wreck from the word go. Its entire data storage model is ill-suited for networked client-server databases, yet a lot of developers stupidly use it that way. I believe you when you say you've seen Access databases getting corrupted by op locks and dropped network connections; Access is fully capable of trashing a database just because you looked at it funny.

Any real database application (and especially business critical ones) should be using something like MS SQL Server or PostgreSQL, not Access.

My point was that, for the use case I believed we were dealing with here (streaming media files to an HTPC), the odds of file corruption due to the HTPC crashing should be very low.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 3:36 pm

just brew it! wrote:Access databases

You keep using those two words in the same sentence... :)
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 3:45 pm

morphine wrote:
just brew it! wrote:Access databases

You keep using those two words in the same sentence... :)

I suppose I could've put "databases" in quotes. :wink:
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 3:52 pm

A more complex solution is to setup a streaming service on the server to make the crashing machine just another dropping client.

just brew it! wrote:Access is fully capable of trashing a database just because you looked at it funny.


Haha! Yes, it is. :)

I pinned most problems on the Jet database. It's pretty disturbing the number of products, and the products, that database was/is used for. Like what goes into a hot dog disturbing.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 4:00 pm

Flatland_Spider wrote:
just brew it! wrote:Access is fully capable of trashing a database just because you looked at it funny.

Haha! Yes, it is. :)

I pinned most problems on the Jet database. It's pretty disturbing the number of products, and the products, that database was/is used for. Like what goes into a hot dog disturbing.

Suffered under poorly-written Jet/Access implementations foisted on us by Federal agencies for years in the day job. To this day I don't think there's a full and accurate compendium of error codes and their meanings.

Thankfully half of it is now SQL and the other half is promised to be by next year.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 4:27 pm

just brew it! wrote:
Ethyriel wrote:Or, perhaps if the media player is in the process of updating metadata.

I would hope that the player would not be touching the metadata unless you've explicitly edited it! For it to do otherwise would arguably be a bug.


Maybe he meant filesystem metadata not media information metadata.

The OP is asking 'if'...which is really hard to answer 100%. I've never heard of a file being corrupted by act of streaming but I suppose it's possible. I would think the server BSOD'ing would be more of a concern than the client. In any case, if you're concerned: 1) backups! 2) Until you've got the client issue solved, use a junk file or just an extra copy to test.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Fri Jan 25, 2013 4:35 pm

MadManOriginal wrote:Maybe he meant filesystem metadata not media information metadata.

In that case the meta-data update would actually be handled on the server side (by the Windows File and Printer Sharing service), and should be atomic (making it reasonably robust against the client dropping off unexpectedly).

MadManOriginal wrote:The OP is asking 'if'...which is really hard to answer 100%. I've never heard of a file being corrupted by act of streaming but I suppose it's possible. I would think the server BSOD'ing would be more of a concern than the client. In any case, if you're concerned: 1) backups! 2) Until you've got the client issue solved, use a junk file or just an extra copy to test.

I didn't rule out the possibility entirely. But IMO it would take a combination of mis-features (arguably bugs) in both the client and server side.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Sat Jan 26, 2013 1:40 am

If the client is just streaming files from the server, why not explicitly make the shares read-only? That should prevent any possibility of data corruption.
Have an upload directory where clients are allowed to write if you need one, but every once in a while move stuff out from there into their proper folders.

\\share
|---movies
| |---pr0n
| \---horse pr0n
|---music
|---photos
\---uploads
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Sat Jan 26, 2013 2:53 am

jihadjoe wrote:If the client is just streaming files from the server, why not explicitly make the shares read-only? That should prevent any possibility of data corruption.
Have an upload directory where clients are allowed to write if you need one, but every once in a while move stuff out from there into their proper folders.

This is how I have my home server set up.
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Sat Jan 26, 2013 11:36 am

jihadjoe wrote:If the client is just streaming files from the server, why not explicitly make the shares read-only? That should prevent any possibility of data corruption.

That's exactly what I suggested about a dozen posts back...
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Re: Can an unstable PC corrupt files stored on a server?

Postposted on Mon Jan 28, 2013 3:50 pm

Woah, this thread really ballooned! :P
In case anyone missed my previous post, I took JBI's (and jihadjoe's, and Waco's) advice to make the shares read only for now.

@derFunkenstein: The power supply in this box is a Corsair HX650, which should easily handle a GTX 660. Also, the machine didn't have any trouble running games. It would only crash during hardware accelerated video playback. Using different drivers and PCI slots didn't help, so I RMAed the card.

Thanks for all of the help!
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