[CentOS] 4.4/64-bit Supermicro/ Nvidia RAID [thanks]

Tue Dec 12 07:19:01 UTC 2006
John R Pierce <pierce at hogranch.com>

Feizhou wrote:
> not so. I used to run boxes that handled 600 to 1000 smtp connections 
> each. Creating and deleting thousands of small files was the 
> environment I worked in.

and if the power failed in the middle of this, how many messages were lost?

> I must say that the 3ware cards on those boxes that had them were not 
> 955x series and therefore had no cache. Perhaps things would have been 
> different if it were 955x cards in there but at that time, the 9xxx 
> 3ware cards were not even out yet.

We typically use 15000 rpm scsi or fiberchannel storage for our 
databases, not SATA.

> Since you have clearly pointed out the performance benefit really 
> comes from the cache (if you have enough) on the board I do not see 
> why using software raid and a battery-backed RAM card like the umem or 
> even the gigabyte i-ram for the journal of the filesystem will be any 
> less slow if at all.

its not the file system journal I'm talking about, its an application 
specific journal file, which contains the indicies and state of the 
queue files, of which there's a very large number constantly being 
written.   We need to flush the queue files AND the journal files for it 
to be safe.   These run around 10GB total as I understand it (not each 
flush, but the aggregate queues can be this big).

if the server has a writeback enabled controller like a HP Smart Array 
5i/532, it all works great.  if it doesn't, it all grinds to a halt.   
quite simple, really.    We have absolutely no desire to start 
architecting around 3rd party ram/battery disks, they won't be supported 
by our production system vendors, and they will make what is currently a 
fairly simple and robust system a lot more convoluted..