On 10/20/2017 01:04 AM, Liwei wrote:

quoted

Note that all of the above can be executed while using your mounted
LV.

Phil

Great! I'm done with the scrub, now waiting for the new drives to
arrive.

I anticipate there'll be quite a bit of downtime involved though.
Our chassis only has 16 cages, so we probably have to temporarily
move one or two of the 2TB drives onto the internal SATA connectors
and hang them around. Power might be an issue too, but we'll figure
it out, hopefully without frying any drives. ;)

My guess is I should probably scrub again after relocating the
drives, just to be sure they work under load.

Good insurance, yes.

Regarding the chunk size, my predecessor initially chose 512k based
on some reading about performance boost with raw video files and
4k/AF drives, not sure whether it holds water. Something along the
lines of: we're dealing with multi gigabyte files anyway, what's
wastage of half a meg here and there? Supposedly RW performance
increases with chunk size - provided they're properly aligned, but it
is a diminishing return.

We're using this NAS to ingest the raw video files from our HD and
4K cameras so they can be accessed remotely for editing, does 512k
chunk size make sense or should I go down to 16/32k?

No, your use calls for the large chunk.  That large chunk could hurt
more random tasks that involve files that aren't much larger than a
stripe.  Your stripes will be 2MB to start, then a bit bigger as you
grow the space.  Gig+ files are much bigger, so no worries.  If your
application was mostly ~10MB files or smaller, or had random access
patterns within the files, I'd reconsider.

Thank you for the assistance so far!

No problem.  I like the easy ones... (-:

Phil