2012-01-09 18:15, John Martin пишет:
On 01/08/12 20:10, Jim Klimov wrote:

Is it true or false that: ZFS might skip the cache and
go to disks for "streaming" reads?
>>  (The more I think
>> about it, the more senseless this sentence seems, and
>> I might have just mistaken it with ZIL writes of bulk
>> data).

I don't believe this was ever suggested. Instead, if
data is not already in the file system cache and a
large read is made from disk should the file system
put this data into the cache?

Hmmm... perhaps THIS is what I could mistake it for...

Thus the correct version of the question goes like this:
is it true or false that some large reads from disk can
be deemed by ZFS as "too big and rare to cache in ARC"?
If yes, what conditions are checked to mark a read as
such? Can this behavior be disabled in order to try and
cache every read (further subject to normal eviction
due to MRU/MFU/memory pressure and other considerations)?

Thanks again,
//Jim Klimov

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