Date: Fri, 5 Dec 2025 13:50:16 +0000 From: void <void@f-m.fm> To: freebsd-fs@freebsd.org Subject: Re: zpool setup clarification Message-ID: <aTLjGLcInHAy5JAo@int21h> In-Reply-To: <20251203081050.1a2880af@arc.aei.uni-hannover.de> References: <aSxnG-HKDYZ0L3lQ@int21h> <b4b75e5e-071c-446f-8298-25f41a609334@app.fastmail.com> <aS8TWJKWqSGeAmo3@int21h> <CANCZdfrxz-swKF5HN_8cZO1A4qmY_x1a1Su2BxAAOQ7JLo6EtQ@mail.gmail.com> <20251203081050.1a2880af@arc.aei.uni-hannover.de>
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On Wed, Dec 03, 2025 at 08:10:50AM +0100, Gerrit Kühn wrote: >Am Tue, 2 Dec 2025 17:32:54 -0700 >schrieb Warner Losh <imp@bsdimp.com>: > >> I always 1MB align partitions, and put the first one with ZFS at a 1MB >> boundary. Though some really large NVMe drives making this 16MB might not >> be bad for performance. > >Same here: > >storage3:~ # gpart show da0 >=> 40 42970644400 da0 GPT (20T) > 40 2008 - free - (1.0M) > 2048 42970640384 1 freebsd-zfs (20T) > 42970642432 2008 - free - (1.0M) > >This is still HDD, but I set up SSDs in pretty much the same way. Usually >it is hard to get information on the internal magic (erase block size >etc.) of SSDs. In the end, we usually struggle more from write patterns we >often see here that only change a few bytes in many (several 10k) files >every few minutes, leading to heavy write amplification. > > >cu > Gerrit I didn't see the other replies (after the initial one) until after the pool was created. Still, *if* a partition needs to be created and therefore if the pool needs to be re-made, it's no problem. The disk is an external 20tb seagate. There's no partition to align right now, I hope this has sidestepped any possible write amplification issue. maybe not? zdb says it has an ashift of 12. I deleted the partitions that were there (think it was exfat32) after removing what was on there by default and then created a (stripe) pool for the disk. --
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