[lustre-devel] RFC: Spill device for Lustre OSD

[Jinshan Xiong]

On Tue, Nov 4, 2025 at 8:37 AM Andreas Dilger <adilger at ddn.com> wrote:

> On Nov 3, 2025, at 18:58, Oleg Drokin via lustre-devel <
> lustre-devel at lists.lustre.org> wrote:
>
>
> On Mon, 2025-11-03 at 16:33 -0800, Jinshan Xiong wrote:
>
> I guess users won't have 1PB OSTs, will they?
>
>
> There probably are already? NASA has a known 0.5P OST configuration:
>
> https://www.nas.nasa.gov/hecc/support/kb/lustre-progressive-file-layout-(pfl)-with-ssd-and-hdd-pools_680.html#:~:text=The%20available%20SSD%20space%20in%20each%20filesystem,decimal%20(far%20right)%20labels%20of%20each%20OST
>
>
In that case, they don't need to use this feature.


>
>
> In order to maximize rebuild performance for declustered parity RAID,
> there are OSTs in production with 90x20TB HDDs = 1.4 PB today,
> and requests to have even larger OSTs.  We've done a bunch of work
> to improve huge ldiskfs OST performance, including the hybrid OST
> patches like https://review.whamcloud.com/51625 ("LU-16750 ldiskfs:
> optimize metadata allocation for hybrid LUNs"), but there could still
> be further improvements in supporting such large OSTs.
>
> Cheers, Andreas
> —
> Andreas Dilger
> Lustre Principal Architect
> Whamcloud/DDN
>
>
>
>
>
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