[sheepdog-users] sheepdog object cache

[Hitoshi Mitake]

I think the problem is already fixed in qemu v2.3.0 or later. The commit:
https://github.com/codyprime/qemu-kvm-jtc/commit/498f21405a286f718a0767c791b7d2db19f4e5bd
would solve the problem. Could you try it?

Thanks,
Hitoshi

On Thu, Apr 7, 2016 at 12:27 PM, 郑晓川 <zhengxiaochuan at jd.com> wrote:

> I had tested sheepdog  on ubuntu server 14.04 (the default qemu is 2.0.0)
>
> The sheepdog  cluster  info :   2 nodes , 2 copies
>
> I started 2 VM by openstack-nova ,and mount sheepdog vdies .
>
> I tested with iozone and fio . the md5sum of vdi obj  became diff from two
> sheepdog node as time goes by .
>
> At the end , I umount the vdi ,  and  check it with  "dog vdi check "  ,
> got :
>
>
>
> after some talk and test Liuy ( you should know him)  told me ,this
> commit may help to resolve the problem. And indeed it works for me .
>
> ----------------------------
> commit 77135d4317ff4e66777f0df760ed254be3d20df5
> Author: Liu Yuan <liuyuan at cmss.chinamobile.com>
> Date:   Wed Jul 29 12:02:35 2015 +0800
>
>     sheepdog: fix overlapping metadata update
>
>
>     Current sheepdog driver use a range update_inode(min_idx, max_idx) for batching
>
>     the updates. But there is subtle problem by determining min_idx and max_idx:
>
>
>     for a single create request, min_idx == max_idx, so actually we just update one
>     one bit as expected.
>
>
>     Suppose we have 2 create request, create(10) and create(20), then min == 10,
>
>     max==20 even though we just need to update index 10 and index 20, update_inode(10,20)
>
>     will actually update range from 10 to 20. This would work if all the update_inode()
>
>     requests won't overlap. But unfortunately, this is not true for some corner case.
>     So the problem arise as following:
>
>     req 1: update_inode(10,20)
>     req 2: update_inode(15,22)
>
>
>     req 1 and req 2 might have different value between [15,20] and cause problems
>
>     and can be illustrated as following by adding a printf in sd_write_done:
>
>
>     @@ -1976,6 +1976,7 @@ static void coroutine_fn sd_write_done(SheepdogAIOCB *acb)
>
>          mn = s->min_dirty_data_idx;
>          mx = s->max_dirty_data_idx;
>     +    printf("min %u, max %u\n", mn, mx);
>          if (mn <= mx) {
>              /* we need to update the vdi object. */
>              offset = sizeof(s->inode) - sizeof(s->inode.data_vdi_id) +
>
>     ...
>     min 4294967295, max 0
>     min 9221, max 9222
>
>
> ------------------------------
> 郑晓川
>
>
> *From:* Hitoshi Mitake <mitake.hitoshi at gmail.com>
> *Date:* 2016-04-07 10:49
> *To:* 郑晓川 <zhengxiaochuan at jd.com>
> *CC:* sheepdog-users <sheepdog-users at lists.wpkg.org>; 江凌生
> <jianglingsheng at jd.com>
> *Subject:* Re: Re: [sheepdog-users] sheepdog object cache
>
>
> On Thu, Apr 7, 2016 at 10:45 AM, 郑晓川 <zhengxiaochuan at jd.com> wrote:
>
>> As i know , there are some bugs on the early version of qemu ( sheepdog
>> driver ) , for example 2.0.0 ,which has "vdi obj inconsistent" 、“discard
>> delete error” bugs 。
>>
>> Which version of qemu and libvirt  is recommend for sheepdog usage。
>>
>
> AFAIK, the bug related to discard is fixed in v2.3.0 or later. And the
> latest libvirt would work fine.
> Could you share the detail of the vdi object inconsistent problem? I'm not
> sure about the problem.
>
> Thanks,
> Hitoshi
>
>
>>
>> Thanks a lot .
>>
>> ------------------------------
>> 郑晓川
>>
>>
>> *From:* Hitoshi Mitake <mitake.hitoshi at gmail.com>
>> *Date:* 2016-04-01 12:33
>> *To:* 郑晓川 <zhengxiaochuan at jd.com>
>> *CC:* sheepdog-users <sheepdog-users at lists.wpkg.org>; 江凌生
>> <jianglingsheng at jd.com>
>> *Subject:* Re: [sheepdog-users] sheepdog object cache
>> Hi,
>>
>> On Mon, Mar 28, 2016 at 10:34 AM, 郑晓川 <zhengxiaochuan at jd.com> wrote:
>>
>>> Hi,all
>>>
>>> what is the last released version , which  still has "object cache"
>>> feature ?
>>> and
>>> I want to kown is this version is  ready for  commercial use ？
>>>
>>
>> v.0.9.3 is the latest stable version.
>>
>>
>>>
>>>
>>> BTW , when  "Sheepdog v1.0"  will come ?
>>>
>>
>> I hope we can release v1.0 early May.
>>
>> Thanks,
>> Hitoshi
>>
>>
>>>
>>> Best regards
>>> ------------------------------
>>>
>>>
>>> --
>>> sheepdog-users mailing lists
>>> sheepdog-users at lists.wpkg.org
>>> https://lists.wpkg.org/mailman/listinfo/sheepdog-users
>>>
>>>
>>
>
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