[sheepdog] [PATCH v4 06/10] sheep: fetch vdi copy list after sheep joins the cluster

[levin li]

On 2012年08月20日 13:15, MORITA Kazutaka wrote:
> At Thu,  9 Aug 2012 13:27:41 +0800,
> levin li wrote:
>>
>> From: levin li <xingke.lwp at taobao.com>
>>
>> The new joined node doesn't have the vdi copy list, or have
>> incomplete vdi copy list, so we need to fetch the copy list
>> data from other nodes
> 
> It makes code complex to store the copy list in local store because
> it's difficult to keep consistency of the data.
> 
> I'd suggest gathering both vid and copy list with SD_OP_READ_VDI
> requests at the same time.  Then we can remove this patch and simplify
> 5th patch a lot.
> 
> Thanks,
> 
> Kazutaka
> 

If we try to read VDI copies by read the VDI inode with SD_OP_READ_VDI,
it maybe expensive, assume there're 1000 VDIs in the cluster, then we should
read 1000 * 4M data through the network when a new node joins.

thanks,

levin