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From "Geir Magnusson Jr." <>
Subject Re: document insert rate
Date Sun, 04 Jan 2009 23:12:05 GMT

On Jan 4, 2009, at 5:12 PM, Alan Bell wrote:

> Geir Magnusson Jr. wrote:
>> On Jan 4, 2009, at 2:59 PM, Damien Katz wrote:
>>> What you say is possible, but doesn't seem too likely as I don't  
>>> ever recall any report of a corrupt db on Linux, but before the  
>>> F_FILESYNC change in Erlang we would see reports of corruptions on  
>>> OS X due to power loss. Since the change, we've had no reports of  
>>> corrupt databases on OS X or Linux.
>> Have you seen the correlation between the # of pirates and global  
>> warming? :)
>> There may be correlation here between the Erlang update and  
>> corruption, but I don't see the causality -  fsync() on linux  
>> should only get as far as the on-device buffering if it does write  
>> buffering, whereas if the OS X docs are truthful, the F_FILESYNC  
>> fcntl() pushs the bits to the rust on the platter.  Maybe they  
>> fixed something else in that erlang update, or maybe the universe  
>> is smiling upon CouchDB users or ....
> . . . maybe the ec2 virtual machine instance and abstracted storage  
> thingie isn't getting to the rust, even though from the point of  
> view of the inside of the VM it thinks it has. I don't know for  
> sure, but a comparitive on a real Linux box would be worthwhile. Do  
> you have some simple benchmark code to share and I will give it a go  
> on a few Linux machines. Would also be interesting to compare SSD to  
> rotating HDD.

Oh, ec2 was way faster, but I have no clue where the storage really is  
- I was going to re-install on the /mnt partition,

I'll put the code on a github project later - was just thinking about  
doing exactly that.  Thanks - I appreciate hearing how your tests go.


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