[Lustre-discuss] MDT overloaded when writting small files in large number

[Balagopal Pillai]

"OST  - 13 ( also act as nfsserver)"

              Then I am assuming that your OSS is also a Lustre client. 
It might be useful to search through this
list to find out the potential pitfalls of mounting Lustre volumes on OSS. 



siva murugan wrote:
> We are trying to uptake Lustre in one of our heavy read/write 
> intensive infrastructure(daily writes - 8million files, 1TB ). Average 
> size of files written is 1KB ( I know , Lustre can't scale well for 
> small size files, but just wanted to analyze the possibility of 
> uptaking )
>  
> Following are some of the tests conducted  to see the difference in 
> large and small file size writting,
>  
> MDT - 1
> OST  - 13 ( also act as nfsserver)
> Clients access lustrefs via NFS ( not patchless clients)
>  
> Test 1 :
>
> Number of clients  - 10
> Dataset size read/written - 971M (per client)
> Number of files in the dataset- 14000
> Total data written - 10gb
> Time taken - 1390s
>
> Test2 :
>
> Number of clients  - 10
> Dataset size read/written -1001M (per client)
> Number of files in the dataset - 4
> Total data written - 10gb
>
> Time taken - 215s
>
>
> Test3 :
>
> Number of clients  - 10
> Dataset size read.written- 53MB (per client)
> Number of files in the dataset- 14000
> Total data written - 530MB
> Time taken - 1027s
> MDT was heavily loaded during  Test3 ( Load average > 25 ). Since the 
> file size in Test 3 is small(1kb) and number of files written is too 
> large(14000 x 10 clients ), obvisouly mdt gets loaded in allocating 
> inodes, total data written in test3 is only 530MB.
>  
> Question  : Is there any parameter that I can tune in MDT to increase 
> the performance when writting large number of small files ?
>
> Please help
>  
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