the system is a dual MOBO 1U from LogicSupply. 
The HDD is a single IDE drive. 
The CPU is a VIA processor and the 
OS is OpenBSD 4.2. 
erlang 12B3
yaws 1.77

There are two nodes and the data is set to replicate.

1 table is a ram_copy
the other 9 tables are disc_copies

The automatic dump_log should have worked although I have no evidence that it didn't. All I know is that the encryption keys failed their sanity checks. Which told me that the data was corrupted some how.

I'm hoping that there are some forensic tools for Mnesia DBs.


---------- Forwarded message ----------
From: Toby Thain <>
Date: Tue, Feb 17, 2009 at 10:17 PM
Subject: Re: [Erlyaws-list] yaws+mnesia+powerfailure = lossed data
To: Richard Bucker <>

On 17-Feb-09, at 6:14 AM, Richard Bucker wrote:

I have a yaws application processes 1 transaction every 10 minutes and
50% of those transactions actually results in a write to a mnesia DB.
The problem, however, is that I've been loosing data. It has happened
3 times so far. Twice when I "stopped" yaws and once when there was a
complete power failure in the datacenter.

I know that there was a failure because the application is a multi-
node encryption key server and a) keys had been passed out to the
client but appeared to be missing from the DB when the keyserver was
restarted; b) the passphrase no longer worked and I can no longer
start the keyserver.

The tables in question are of type disc_copies and everything is
always inside a transaction/1 and I never do dirty_* anything. so?

- is there a better way to shutdown a yaws node other than "yaws --stop"
- should I be using a different table type to insure ACID?
- how do I insure that the data is committed to disk?
- maybe it's time for a die_mod?

Just out of interest, can you describe your whole stack down to the hardware... including any RAID or volume manager.



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