[synoinfo.conf will automatic change back after modifucation?]

I have a DSM1517+, it have 5 internal sata port and 2 Esata port.  Now I have install 5 harddisk and I want to add a SSD as read cache, and install the SSD on esata port.

so I want  to modify synoinfo.conf to change esata to internal sata drive.

 

Below are 2 file need to be changed.

 /etc/synoinfo.conf 

 /etc.defaults/synoinfo.conf 

 

the content is changed from:

internalportcfg="0x1f"
esataportcfg="0x60"
maxdisks="5"

 

to

internalportcfg="0x7f"
esataportcfg="0x80"
maxdisks="7"

And I have confirmed that I have login as root, configmed the file with Winscp after I did the changed the content.

but after I restart DSM, I found  the data what I have changed in /etc.defaults/synoinfo.conf are all changed back......

I redo it again, it still changed back.

So my question is who have ever met same issue and how to fix it.