On May 11, 2022, at 08:25, Nathan Dauchy wrote:
>
> Greetings!
Hello Nathan,
> During the helpful LUG tutorial from Rick Mohr on advanced lustre file
> layouts, it was mentioned that “lfs mirror” could be used to improve read
> performance. And the manual supports this, stating “files that
When using PFL, and using an SSD as the first extent, it seems it would
be advantageous to not have that extent's file data consume memory in
the client's system buffers. It would be similar to using O_DIRECT, but
on a per-extent basis. Is there a mechanism for that already?
Thanks,
John
No, and I'm not sure I agree with you at first glance.
Is this just generally an idea that data stored on SSD should not be in RAM?
If so, there's no mechanism for that other than using direct I/O.
-Patrick
From: lustre-discuss on behalf of
John Bauer
Sent:
Well, you could use two file descriptors, one for O_DIRECT one otherwise.
SSD is a fast medium but my instinct is the desirability of having data in RAM
is much more about I/O pattern and hard to optimize for in advance - Do you
read the data you wrote? (Or read data repeatedly?)
In any
Pat,
No, not in general. It just seems that if one is storing data on an
SSD it should be optional to have it not stored in memory ( why store in
2 fast mediums ).
O_DIRECT is not of value as that would apply to all extents, whether on
SSD on HDD. O_DIRECT on Lustre has been problematic
