[ale] Disk IO Question

[mmillard1 at comcast.net]

Right now we're using the cpio to copy the data. If there is a faster option I'm open to at least try it. 


Thanks to everyone for your suggestions, I'll take any advice I can get. 

----- 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 5:45:49 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [ale] Disk IO Question 

On Thu, Oct 29, 2009 at 4:49 PM, <mmillard1 at comcast.net> wrote: 
> I have a Suse OES server running on an IBM 346with 2 gig of RAM. I've 
> installed two Addonics Multilane SATA cards connect with Multilane cables 
> to external SATA enclosures housing 4 WD Caviar Green 1.5 TB Drives. 
> 
> 
> 
> I have about 1.8 TB of Data on one Enclosure which changes daily. My plan 
> was to copy the 1.8 TB to the second enclosure daily and send the drives in 
> that unit off site. 

How are you copying? dd, rsync, cp --archive, etc. 

> My expectation was that by having 4 independant SATA paths per unit 
> would give me substantial performance when moving data between these units. 

I agree. 

> I'm seeing a constant speed of about 60 gig per hour. This is much slower 
> than I expected. Have any of you done anything like this? Is this the kind 
> of performance I should expect? Hopefull some of you bright people can 
> share some wisdom with me. 

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. 

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. 

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.) 

Greg 

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