help needed - tuning a filesystem for rm and cp ? (MORE)

[Eric Anderson]

Gore Jarold wrote:
> On Fri, 13 Jul 2007, Ivan Voras wrote:
> 
>> Gore Jarold wrote:
>>
>>> vfs.ufs.dirhash_maxmem: 2097152
>>> vfs.ufs.dirhash_mem: 2065716
>>>
>>>
>>> Interesting at all ?
>> Yes, you've used up all dirhash_mem. Since you have
> enough memory, try
>> increasing dirhash_maxmem by a factor of 4 or more
> and testing again. It
>> might help you with large directories (lots of
> files).
> 
> 
> Ok, you are correct - I am indeed maxing out
> vfs.ufs.dirhash_mem
> 
> I have just upped it by 2x and will continue to
> monitor it.
> 
> Here is a question for any and all out there reading
> ... what would you expect would happen to a system
> that was constantly maxing out this value, sometimes
> on a sustained basis, while the activity that caused
> it went on uninterrupted ?
> 
> I am seeing the system halt ... is it reasonable to
> think that maxing that value out on a regular,
> sustained basis would cause a system to halt ?
> 
> (6.2-release running on a 4 GB memory p4 xeon ... does
> nothing but fileserver duties)


If you have a lot of meta-data IO (which you seem to have), then it's 
possible that the system is incredibly busy doing disk accesses, and 
waiting on IO from storage.  When you say 'halt' does that mean you 
can't log in to it, and eventually it comes back alive, or does that 
mean it is locked up in a way that never recovers?

Eric