Re: [Zope] Lost Objects after System Crash (Zope 2.1.5 on Win32)
I upgraded to Zope 2.1.5 (Win 32) Saturday and carried out changes in the database (eg. created new ZClasses, added ZClass instances, etc.)
I had a nasty system crash (Win 95) around midnight Saturday. When I reopened Zope I realised the database was back to its 16:22 status: - All new objects had vanished. - The last transaction logged in the Undo list is dated about 16:22. - The very Data.fs in the filesystem is stamped 16:22 if you can believe it.
I checked the Z2.log and it shows these missing changes. So I didn't dreamt doing them.
I suppose these changes are lost?
I had the same experience a few days ago with a 2.1.4 installation running under Win98. I have a couple of different Zope instances running on Linux and Windows, but that was the first data loss. It seemed to me as if the session had been running in "demo" mode so that changes would not be really persistent. As in Alexandre's case, I first thought I was dreaming because there was no hint of my data except for the log files. I suggest some further investigation into that. If Zope really lost things that easily, I'd consider not using ZODB for production sites ... BTW: In my case it also was a Windows system crash that caused the data loss. Joachim Werner. -------------------------------------------------------
On Tue, Mar 21, 2000 at 09:59:40AM +0100, Joachim Werner wrote:
I upgraded to Zope 2.1.5 (Win 32) Saturday and carried out changes in the database (eg. created new ZClasses, added ZClass instances, etc.)
I had a nasty system crash (Win 95) around midnight Saturday. When I reopened Zope I realised the database was back to its 16:22 status: - All new objects had vanished. - The last transaction logged in the Undo list is dated about 16:22. - The very Data.fs in the filesystem is stamped 16:22 if you can believe it.
I checked the Z2.log and it shows these missing changes. So I didn't dreamt doing them.
I suppose these changes are lost?
I had the same experience a few days ago with a 2.1.4 installation running under Win98. I have a couple of different Zope instances running on Linux and Windows, but that was the first data loss. It seemed to me as if the session had been running in "demo" mode so that changes would not be really persistent. As in Alexandre's case, I first thought I was dreaming because there was no hint of my data except for the log files.
I suggest some further investigation into that. If Zope really lost things that easily, I'd consider not using ZODB for production sites ...
BTW: In my case it also was a Windows system crash that caused the data loss.
This sounds like Win98 is using a write-cache that didn't get flushed to disk because of the crah. IIRC, Zope forces write cache flushes, but it could well be that Win98, being a client-patform, ignores that for performance reasons. Then again, who'd use Win98 for production sites? -- Martijn Pieters | Software Engineer mailto:mj@digicool.com | Digital Creations http://www.digicool.com/ | Creators of Zope http://www.zope.org/ | The Open Source Web Application Server ---------------------------------------------
Martijn, you're right. Nobody would use Win98 on production systems. But quite a few people use it on their notebooks or home PCs for development, I guess. At least that is what I do. If your assumption that a Windows cache problem is the reason for the data loss, is right, that would mean that Win98 must be holding the whole DATA.FS in memory/virtual memory without saving for hours! In that case it might be a good idea to warn everybody to shutdown and restart Zope under Windows 9x after major changes. BTW: So far, I've never lost data when I just "killed" the Zope process. So Windows seems to save data at least in that case ... Joachim.
This sounds like Win98 is using a write-cache that didn't get flushed to disk because of the crah. IIRC, Zope forces write cache flushes, but it could well be that Win98, being a client-patform, ignores that for performance reasons.
Then again, who'd use Win98 for production sites?
participants (2)
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Joachim Werner -
Martijn Pieters