[Gluster-users] Gluster v 3.3 with KVM and High Availability

[Samuli Heinonen]

On 12.07.2012 11:40, Mark Nipper wrote:
> Something concerns me about those performance figures.
> If I'm reading them correctly, the normal fuse mount performance
> is about what I was seeing, 2-3MB.  And now bypassing everything,
> libglusterfs is still capping out a little under 20MB/s.

It's running tests on four files at the same time. Minb shows speed of 
slowest test, maxb is the fastest and aggrb shows all four tests 
aggregated.

> So am I kidding myself that approaching 45-50MB/s with a
> FUSE based Gluster mount and using cache=writethrough is actually
> a safe thing to do really?  I know the performance is abysmal
> without setting the cache mode, but is using writethrough really
> safe, or is it a recipe for disaster waiting to happen?

When using writethrough the data is written to cache but not marked 
finished before it has hit the disk. Data in cache can be then used to 
speed up read operations. So I would consider it pretty safe, but 
perhaps someone else can explain it better?