On 10/20/2017 01:04 AM, Liwei wrote: >> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
