topic Re: Smart Array 5i Plus Controller and Battery Backed Write Cache Enabler in ProLiant Servers (ML,DL,SL)

Smart Array 5i Plus Controller and Battery Backed Write Cache Enabler

Steven Hellyer — Thu, 06 Mar 2003 21:20:04 GMT

Does anyone know if the Smart Array 5i Plus Controller is specifically designed for use with databases?

According to Microsoft you run the risk of database corruption if you use a write-caching disk controller that is not designed for databases.

This is because SQL Server relies on the Windows OS to notify it when an I/O operation has completed. If anyone has any insight on this I would be very grateful.

Thanks,

Steven

Re: Smart Array 5i Plus Controller and Battery Backed Write Cache Enabler

Bob Bell_1 — Thu, 06 Mar 2003 21:58:36 GMT

Although I do not know if this specific controller is "designed" for specific db use, Most descent controllers will allow you to set the write-through and write-back cache policies to suite your needs and comfort levels. I am fairly certain this is true about the SA 5i controller too..

Re: Smart Array 5i Plus Controller and Battery Backed Write Cache Enabler

Bob Bell_1 — Thu, 06 Mar 2003 22:05:35 GMT

Just a note: it would be that the controller signals as a successful (i/o completion) "write" to the cache or the disk that is difference in the write-back (cache) and write-through (disk)..

Re: Smart Array 5i Plus Controller and Battery Backed Write Cache Enabler

Glenn Weavind_1 — Mon, 10 Mar 2003 08:52:27 GMT

I think you'll find that all of the HP/Compaq write-cacheing array controllers meet your requirements. The only possible issue is that one thread of your DB writes to the DB - and the array controller caches it: if another thread now attempts to read the same record information, a well designed array controller will fulfill the request from the recently updated cache (which give the DB thread the latest, correct informtion). A poorly designed array controller would supply information from HDD, and supply out-of-date information. Such an array controller would rapidly become notorious, and stop selling.
I think you'll find that the Microsoft 'advice' is teaching granny to suck eggs.