[ale] Disk IO Question

[mmillard1 at comcast.net]

Absolutely, If I can get back to the office I'll even do it tonight, otherwise it might be tomorrow. 


Thanks for your help 

----- Original Message ----- 
From: "Greg Freemyer" <greg.freemyer at gmail.com> 
To: "Atlanta Linux Enthusiasts - Yes! We run Linux!" <ale at ale.org> 
Sent: Thursday, October 29, 2009 6:34:24 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [ale] Disk IO Question 

Can you comment on / answer the rest of my post? 

> 60 GB per hour may or may not be slow. If the files are very small, I 
> find 100K files / hr to be a limiting factor in some cases. 
> 
So how many files per hour are you currently seeing? 

> I also do a lot of "dd if=/dev/sdb of=/dev/sdc bs=4k 
> conv=noerror,sync" copying of filesystems. I see speeds of 250GB/hr 
> even with just drive to drive transfers. You raid array should be 
> much faster. 

Even as a test can try this? If you don't unmap the source array, the 
dest will not be a good copy, but this would still be a good 
performance test. 

> So if you can unmount your primary drive every night, you should be 
> able to make a dd copy every night. I have one vendor that is telling 
> me they are moving data around at 1TB/hr. (I'm not sure how true that 
> is.) 

If unmounting every night is a problem, consider LVM snapshots? They 
allow you to make a "point-in-time" copy that requires hours to 
actually make. 

Greg 
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