[ale] Disk IO Question

[Greg Freemyer]

Don't go back to the office over it.  I just thought you had missed
half of my original post.

On Thu, Oct 29, 2009 at 6:44 PM,  <mmillard1 at comcast.net> wrote:
> 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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Greg Freemyer
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