Re: [PATCH mdadm v7 0/7] Write Zeroes option for Creating Arrays

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 3/1/2023 12:41 PM, Logan Gunthorpe wrote:
> Hi,
> 
> This is the next iteration of the patchset to add a zeroing option
> which bypasses the inital sync for arrays. This version of the patch
> has some minor cleanup and collected a number of review and ack tags.
> 
> This patch set adds the --write-zeroes option which will imply
> --assume-clean and write zeros to the data region in each disk before
> starting the array. This can take some time so each disk is done in
> parallel in its own fork. To make the forking code easier to
> understand this patch set also starts with some cleanup of the
> existing Create code.
> 
> We tested write-zeroes requests on a number of modern nvme drives of
> various manufacturers and found most are not as optimized as the
> discard path. A couple drives that were tested did not support
> write-zeroes at all but still performed similarly with the kernel
> falling back to writing zero pages. Typically we see it take on the
> order of one minute per 100GB of data zeroed.
> 
> One reason write-zeroes is slower than discard is that today's NVMe
> devices only allow about 2MB to be zeroed in one command where as
> the entire drive can typically be discarded in one command. Partly,
> this is a limitation of the spec as there are only 16 bits avalaible

's/avalaible/available/g'

> in the write-zeros command size but drives still don't max this out.
> Hopefully, in the future this will all be optimized a bit more
> and this work will be able to take advantage of that.
> 
> Logan
> 
> --
> 
>

Based on earlier discussion and feedback from Martin this
whole series looks good to me.

Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>

-ck






[Index of Archives]     [Linux RAID Wiki]     [ATA RAID]     [Linux SCSI Target Infrastructure]     [Linux Block]     [Linux IDE]     [Linux SCSI]     [Linux Hams]     [Device Mapper]     [Device Mapper Cryptographics]     [Kernel]     [Linux Admin]     [Linux Net]     [GFS]     [RPM]     [git]     [Yosemite Forum]


  Powered by Linux