Re: ext4 in CentOS 5.6?

[Les Mikesell <lesmikesell@xxxxxxxxx>]

On 7/5/2011 1:30 PM, Rudi Ahlers wrote:
> On Tue, Jul 5, 2011 at 8:20 PM, Les Mikesell<lesmikesell@xxxxxxxxx>  wrote:
>>
>> How much can that matter?  Reads are going to be cached in main RAM
>> anyway - which is pretty cheap these days.
>>
>
>
> Yes, but I suppose it all depends on the needs of the server in question :)
>
> In our case, with web servers, reads (i.e. opening websites,
> downloading content) far outweighs writes (which are basically logs,
> file uploads, and sessions being written to disk.
>
> In case of forums (we have many clients with forums) reads&  writes
> are sometimes equal, but even then reads are still more common in our
> case than writes.

But it doesn't matter if you lose the read cache in RAM - and the OS is 
going to keep a copy there as long as it can anyway.  The point of SSD 
caching of journals/writes is that it survives a reboot.  If you have a 
lot more SSD than spare RAM it might save a few seeks as a side effect 
but why not just add RAM if that matters?

-- 
   Les Mikesell
    lesmikesell@xxxxxxxxx


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