* question about raid10 near copy info in man mdadm.
@ 2012-04-16 5:28 kedacomkernel
2012-04-16 5:41 ` NeilBrown
0 siblings, 1 reply; 6+ messages in thread
From: kedacomkernel @ 2012-04-16 5:28 UTC (permalink / raw)
To: Neil Brown; +Cc: linux-raid
Hi:
I readed the information about raid10 near copy in man mdadm.
It is:
'n' signals 'near' copies. Multiple copies of one data block are at similar offsets in different
devices.
But I think this wrong.
If raid10 had five disks and near copy is equal three.
The layout like:
5 disks
--------------------
A1 A1 A1 A2 A2
A2 A3 A3 A3 A4
But the copies of datablock A2 are not at similar offset in different device.
--------------
kedacomkernel
2012-04-16
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: question about raid10 near copy info in man mdadm.
2012-04-16 5:28 question about raid10 near copy info in man mdadm kedacomkernel
@ 2012-04-16 5:41 ` NeilBrown
2012-04-16 5:46 ` kedacomkernel
0 siblings, 1 reply; 6+ messages in thread
From: NeilBrown @ 2012-04-16 5:41 UTC (permalink / raw)
To: kedacomkernel; +Cc: linux-raid
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On Mon, 16 Apr 2012 13:28:14 +0800 "kedacomkernel" <kedacomkernel@gmail.com>
wrote:
> Hi:
> I readed the information about raid10 near copy in man mdadm.
> It is:
> 'n' signals 'near' copies. Multiple copies of one data block are at similar offsets in different
> devices.
> But I think this wrong.
> If raid10 had five disks and near copy is equal three.
> The layout like:
> 5 disks
> --------------------
> A1 A1 A1 A2 A2
> A2 A3 A3 A3 A4
>
> But the copies of datablock A2 are not at similar offset in different device.
>
They are certainly on different devices so I guess you are questioning the
use of the word "similar".
What do you understand "similar" to mean?
How would you describe offsets which might be the same, or might differ by
one chunk-size?
I'm happy to change the text if it is confusing, but only if the result is
undoubtedly less confusing.
NeilBrown
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Re: question about raid10 near copy info in man mdadm.
2012-04-16 5:41 ` NeilBrown
@ 2012-04-16 5:46 ` kedacomkernel
2012-04-16 6:01 ` NeilBrown
2012-04-16 6:10 ` kedacomkernel
0 siblings, 2 replies; 6+ messages in thread
From: kedacomkernel @ 2012-04-16 5:46 UTC (permalink / raw)
To: NeilBrown; +Cc: linux-raid
This is the man md about:
When 'near' replicas are chosen, the multiple copies of a given chunk are laid out consecutively across
the stripes of the array, so the two copies of a datablock will likely be at the same offset on two
adjacent devices.
I think the word "similar" is the same.
------------------
kedacomkernel
2012-04-16
-------------------------------------------------------------
发件人：NeilBrown
发送日期：2012-04-16 13:41:33
收件人：kedacomkernel
抄送：linux-raid
主题：Re: question about raid10 near copy info in man mdadm.
On Mon, 16 Apr 2012 13:28:14 +0800 "kedacomkernel" <kedacomkernel@gmail.com>
wrote:
> Hi:
> I readed the information about raid10 near copy in man mdadm.
> It is:
> 'n' signals 'near' copies. Multiple copies of one data block are at similar offsets in different
> devices.
> But I think this wrong.
> If raid10 had five disks and near copy is equal three.
> The layout like:
> 5 disks
> --------------------
> A1 A1 A1 A2 A2
> A2 A3 A3 A3 A4
>
> But the copies of datablock A2 are not at similar offset in different device.
>
They are certainly on different devices so I guess you are questioning the
use of the word "similar".
What do you understand "similar" to mean?
How would you describe offsets which might be the same, or might differ by
one chunk-size?
I'm happy to change the text if it is confusing, but only if the result is
undoubtedly less confusing.
NeilBrown
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: question about raid10 near copy info in man mdadm.
2012-04-16 5:46 ` kedacomkernel
@ 2012-04-16 6:01 ` NeilBrown
2012-04-16 6:10 ` kedacomkernel
1 sibling, 0 replies; 6+ messages in thread
From: NeilBrown @ 2012-04-16 6:01 UTC (permalink / raw)
To: kedacomkernel; +Cc: linux-raid
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On Mon, 16 Apr 2012 13:46:46 +0800 "kedacomkernel" <kedacomkernel@gmail.com>
wrote:
> This is the man md about:
> When 'near' replicas are chosen, the multiple copies of a given chunk are laid out consecutively across
> the stripes of the array, so the two copies of a datablock will likely be at the same offset on two
> adjacent devices.
"likely" is different from "certainly". In most cases they are the same
offset. In some cases they are different offsets. I think "likely"
describes that well enough.
>
> I think the word "similar" is the same.
"similar" is not the same as "same", though it is similar .....
"same" means there is no difference.
"similar" means there might be a difference, but it is not a big difference.
Does that clear it up?
NeilBrown
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: Re: question about raid10 near copy info in man mdadm.
2012-04-16 5:46 ` kedacomkernel
2012-04-16 6:01 ` NeilBrown
@ 2012-04-16 6:10 ` kedacomkernel
2012-04-16 6:20 ` NeilBrown
1 sibling, 1 reply; 6+ messages in thread
From: kedacomkernel @ 2012-04-16 6:10 UTC (permalink / raw)
To: NeilBrown; +Cc: linux-raid
Why not use md's description instead of mdadm' content?
I think this may be better,especially for people who's native language is not English.
------------------
kedacomkernel
2012-04-16
-------------------------------------------------------------
发件人：NeilBrown
发送日期：2012-04-16 14:01:18
收件人：kedacomkernel
抄送：linux-raid
主题：Re: question about raid10 near copy info in man mdadm.
On Mon, 16 Apr 2012 13:46:46 +0800 "kedacomkernel" <kedacomkernel@gmail.com>
wrote:
> This is the man md about:
> When 'near' replicas are chosen, the multiple copies of a given chunk are laid out consecutively across
> the stripes of the array, so the two copies of a datablock will likely be at the same offset on two
> adjacent devices.
"likely" is different from "certainly". In most cases they are the same
offset. In some cases they are different offsets. I think "likely"
describes that well enough.
>
> I think the word "similar" is the same.
"similar" is not the same as "same", though it is similar .....
"same" means there is no difference.
"similar" means there might be a difference, but it is not a big difference.
Does that clear it up?
NeilBrown
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: question about raid10 near copy info in man mdadm.
2012-04-16 6:10 ` kedacomkernel
@ 2012-04-16 6:20 ` NeilBrown
0 siblings, 0 replies; 6+ messages in thread
From: NeilBrown @ 2012-04-16 6:20 UTC (permalink / raw)
To: kedacomkernel; +Cc: linux-raid
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On Mon, 16 Apr 2012 14:10:28 +0800 "kedacomkernel" <kedacomkernel@gmail.com>
wrote:
> Why not use md's description instead of mdadm' content?
> I think this may be better,especially for people who's native language is not English.
>
Send me a patch which you think is an improvement.
If I agree, I'll apply it.
Thanks,
NeilBrown
> ------------------
> kedacomkernel
> 2012-04-16
>
> -------------------------------------------------------------
> 发件人：NeilBrown
> 发送日期：2012-04-16 14:01:18
> 收件人：kedacomkernel
> 抄送：linux-raid
> 主题：Re: question about raid10 near copy info in man mdadm.
>
> On Mon, 16 Apr 2012 13:46:46 +0800 "kedacomkernel" <kedacomkernel@gmail.com>
> wrote:
>
> > This is the man md about:
> > When 'near' replicas are chosen, the multiple copies of a given chunk are laid out consecutively across
> > the stripes of the array, so the two copies of a datablock will likely be at the same offset on two
> > adjacent devices.
>
> "likely" is different from "certainly". In most cases they are the same
> offset. In some cases they are different offsets. I think "likely"
> describes that well enough.
>
> >
> > I think the word "similar" is the same.
>
> "similar" is not the same as "same", though it is similar .....
>
> "same" means there is no difference.
> "similar" means there might be a difference, but it is not a big difference.
>
> Does that clear it up?
>
> NeilBrown
>
>
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2012-04-16 5:28 question about raid10 near copy info in man mdadm kedacomkernel
2012-04-16 5:41 ` NeilBrown
2012-04-16 5:46 ` kedacomkernel
2012-04-16 6:01 ` NeilBrown
2012-04-16 6:10 ` kedacomkernel
2012-04-16 6:20 ` NeilBrown
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