Thank you for your reply.
In glusterfs,Some metadata information is recorded in the file's extended attr in all
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.
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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