Unsolved
This post is more than 5 years old
4 Posts
0
1012
WT cache for vplex loacl mirror
Anyone has known why cache was set to be WT (Write Thought) for vlpex local mirror configuration? Cache was known as speedup, especially when one mirror leg with low-grade performance.
hello_3k
4 Posts
0
July 29th, 2012 23:00
Thanks for you answer, but this is not what I want.
As you know, local mirror is used for local HA, In cache WT module, system will not ack to host untill all mirror leg writing back,so the slower mirror leg will cause latence.It is bad if one of the BE array was in degrade status.
zhouzengchao
2 Intern
2 Intern
•
1.4K Posts
0
July 29th, 2012 23:00
the design is for data consistency between Sync distance. Generally, Sync distance could provide <5ms latency which is accpetable to most applications. Although the performance is lower than write-back cache mode, but you or applicatoin won't feel difference from performance perspective under most of the cases.
zhouzengchao
2 Intern
2 Intern
•
1.4K Posts
0
July 30th, 2012 04:00
It is not a product design issue, it is the i/o pattern by nature. of course you can choose write-back mode provided by Geo, but you should be able to afford non-zero RPO. It depends on your environment.