[OpenAFS] memcache or diskcache on ramdisk

[Hartmut Reuter]

EC wrote:
> Hi,
> 
> Do using memory cache for AFSD 'better' (faster, more stable, etc..) than
> disk cache over RAMDISK or TMPFS ?
> 
> EC. 

My experience with 1.3.74 is that memcache is really fast. We reach 70 MB/s
for write and 48 MB/s for read of an 8 GB file which is about 20 MB/s 
faster than
with ramdisk. This was on SuSE SLES-9 with kernel 2.6.5-7.

With the 2.6 kernel there is still a problem that the disk cache gets 
full which makes
the use of ramdisk nearly impossible.

Of course disk cache still makes sense if your network is slower than 
your local
disk. But in production environments such as blade centres the network 
typically
is much faster than the internal disk.

Hartmut


> 
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Hartmut Reuter                           e-mail reuter@rzg.mpg.de
					   phone +49-89-3299-1328
RZG (Rechenzentrum Garching)               fax   +49-89-3299-1301
Computing Center of the Max-Planck-Gesellschaft (MPG) and the
Institut fuer Plasmaphysik (IPP)
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