RE: Forming drives together into a cache hierarchy
> From: Paul Richards [mailto:paul.richards@gmail.com]
> Sent: Wednesday, September 02, 2009 3:30 AM
>
> Is there a way to combine a large slow drive with a fast small drive
> in such a way that the faster drive simply becomes a cache for the
> larger drive?
>
> I imagine a computer where I'd like to have a small fast SSD and a
> large but slow spinning disk. I'd like to put the two block devices
> together so that I'm presented with a single logical block device,
> where the operating system is using the SSD as a cache (either
> inclusive or exclusive, write-though or otherwise) of the spinning
> disk.
>
> Is there some magic in LVM that can do this?
>
> If there is nothing at the block device level can it be done at the
> filesystem level?
Using an SSD as a cache for a hard drive isn't a good idea, since SSD's are orders of magnitude slower in writing than hard drives are. Put your OS on an SSD, and put /home (and probably /var and /tmp) on a fast hard drive, and call it a day.
Here's a great article giving you more info than you probably ever wanted to know about the various flavors of SSDs: http://www.anandtech.com/storage/showdoc.aspx?i=3531
Hope this helps!
-- Kevin
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