Re: hello, I am confused about a question of rbd

Re: hello, I am confused about a question of rbd

[Jason Dillaman]

According to the git history, support for zero MB images for the create/resize commands was explicitly added by commit 08f47a4.  Dan Mick or Josh Durgin could probably better explain the history behind the change since it was before my time.

-- 

Jason Dillaman 
Red Hat 
dillaman@redhat.com 
http://www.redhat.com 


----- Original Message ----- 

> From: "zhengbin 08747" <zhengbin.08747@h3c.com>
> To: dillaman@redhat.com
> Sent: Thursday, July 23, 2015 7:52:16 AM
> Subject: hello, I am confused about a question of rbd

> When I create a rbd block, its size can be zero, why?I think it should not be
> zero, If it should not be zero, I will report a bug and fix it,thank you

> Like this, I create a rbd block name foo2, it can not be use

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Re: hello, I am confused about a question of rbd

[Dan Mick]

Why not zero?

If the answer is "it can't be used", then, what arbitrary minimum size
is too small?

(also, given that resize exists, it can be used for storage after a resize.)

On 07/23/2015 06:03 AM, Jason Dillaman wrote:
> According to the git history, support for zero MB images for the create/resize commands was explicitly added by commit 08f47a4.  Dan Mick or Josh Durgin could probably better explain the history behind the change since it was before my time.
> 

Re: 答复: hello, I am confused about a question of rbd

[Dan Mick]

Adding back ceph-devel

My point was, ok, ruling out 0, then we can create a block device of
size 1 byte.  Is that useful?  No, it is not.  How about 10 bytes?
1000?  1MB?

There's no good reason to rule out zero.  Is it causing a problem somehow?

On 07/23/2015 06:06 PM, zhengbin.08747@h3c.com wrote:
> If I create a block whose size is zero, it means you absolutely can not use it unless you resize it
> 
> 
> what arbitrary minimum size is too small?  -----> I do not know, If I create a block whose size is larger than zero,it may be can use.
> And why do we have to define a minimum size? we can just make sure the block size is larger than zero
> 
> -----邮件原件-----
> 发件人: Dan Mick [mailto:dmick@redhat.com]
> 发送时间: 2015年7月24日 5:25
> 收件人: Jason Dillaman; zhengbin 08747 (RD)
> 抄送: ceph-devel
> 主题: Re: hello, I am confused about a question of rbd
> 
> Why not zero?
> 
> If the answer is "it can't be used", then, what arbitrary minimum size is too small?
> 
> (also, given that resize exists, it can be used for storage after a resize.)
> 
> On 07/23/2015 06:03 AM, Jason Dillaman wrote:
>> According to the git history, support for zero MB images for the create/resize commands was explicitly added by commit 08f47a4.  Dan Mick or Josh Durgin could probably better explain the history behind the change since it was before my time.
>>
> 
> -------------------------------------------------------------------------------------------------------------------------------------
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> 的个人或群组。禁止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、复制、
> 或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并删除本
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> 

-- 
Dan Mick
Red Hat, Inc.
Ceph docs: http://ceph.com/docs
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答复: 答复: hello, I am confused about a question of rbd

[zhengbin.08747]

From now I don't find any question, Understand it, thank you

-----邮件原件-----
发件人: Dan Mick [mailto:dmick@redhat.com] 
发送时间: 2015年7月24日 9:21
收件人: zhengbin 08747 (RD); ceph-devel
主题: Re: 答复: hello, I am confused about a question of rbd

Adding back ceph-devel

My point was, ok, ruling out 0, then we can create a block device of size 1 byte.  Is that useful?  No, it is not.  How about 10 bytes?
1000?  1MB?

There's no good reason to rule out zero.  Is it causing a problem somehow?

On 07/23/2015 06:06 PM, zhengbin.08747@h3c.com wrote:
> If I create a block whose size is zero, it means you absolutely can 
> not use it unless you resize it
> 
> 
> what arbitrary minimum size is too small?  -----> I do not know, If I create a block whose size is larger than zero,it may be can use.
> And why do we have to define a minimum size? we can just make sure the 
> block size is larger than zero
> 
> -----邮件原件-----
> 发件人: Dan Mick [mailto:dmick@redhat.com]
> 发送时间: 2015年7月24日 5:25
> 收件人: Jason Dillaman; zhengbin 08747 (RD)
> 抄送: ceph-devel
> 主题: Re: hello, I am confused about a question of rbd
> 
> Why not zero?
> 
> If the answer is "it can't be used", then, what arbitrary minimum size is too small?
> 
> (also, given that resize exists, it can be used for storage after a 
> resize.)
> 
> On 07/23/2015 06:03 AM, Jason Dillaman wrote:
>> According to the git history, support for zero MB images for the create/resize commands was explicitly added by commit 08f47a4.  Dan Mick or Josh Durgin could probably better explain the history behind the change since it was before my time.
>>
> 
> ----------------------------------------------------------------------
> ---------------------------------------------------------------
> 本邮件及其附件含有杭州华三通信技术有限公司的保密信息，仅限于发送给上面地址中列出
> 的个人或群组。禁止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、复制、
> 或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并删除本
> 邮件！
> This e-mail and its attachments contain confidential information from 
> H3C, which is intended only for the person or entity whose address is 
> listed above. Any use of the information contained herein in any way 
> (including, but not limited to, total or partial disclosure, 
> reproduction, or dissemination) by persons other than the intended
> recipient(s) is prohibited. If you receive this e-mail in error, 
> please notify the sender by phone or email immediately and delete it!
> 

--
Dan Mick
Red Hat, Inc.
Ceph docs: http://ceph.com/docs