Re: Feature support: development of metadata service xlator plugin in glusterfs.

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Thank you for your reply.
In glusterfs,Some metadata information is recorded in the file's extended attr in all
bricks,
For example EC volume, N+M mode, stat file requires N+M command,
file write, requires M+M lock, record file length, and also N+M setattr command,
Finally n+m unlock command;
if have metadataserver,All metadata related operations
only one command to metadata server;
As the old topic, MKDIR requires that all the DHT children should be executed Mkdir;
Another difficult problem, lack of centralized metadata; disk recovery performance is not able to get a massive upgrade;Such as EC N+M volume, disk reconstruction, and only bricks n+m to participate in the reconstruction;Rebuilding 1TB takes several hours;
The use of metadata, the data can be dispersed to all the disk,Disk failure, a lot of disk can be involved in the reconstruction;
How to solve these difficulties.










At 2015-06-21 05:31:58, "Vijay Bellur" <vbellur@xxxxxxxxxx> wrote: >On Friday 19 June 2015 10:43 PM, 张兵 wrote: >> Hi all >> In the use of the glusterfs ,found file system commands a lot, such >> as stat, lookup,setfattr, the very influence system performance, >> especially with EC volume. The use of glusterfs code architecture and >> add metadata server xlater and achieve similar GFS architecture; so, the >> same set of software, users can choose their own metadata server or not >> to choose the metadata server; > >How do you expect the metadata server to aide performance here? There >would be network trips to the metadata servers to set/fetch necessary >information. If the intention is to avoid the penalty of having to fetch >information from disk, we have been investigating the possibility of >loading md-cache as part of the brick process graph to avoid hitting the >disk for repetitive fetch of attributes & extended attributes. I expect >that to be mainlined soon. > >If you have other ideas on how a metadata server can improve >performance, that would be interesting to know. > >Regards, >Vijay > >


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