From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: linan666@huaweicloud.com
Cc: <song@kernel.org>, <yukuai3@huawei.com>,
<martin.petersen@oracle.com>, <hare@suse.de>, <axboe@kernel.dk>,
<linux-raid@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<bvanassche@acm.org>, <hch@infradead.org>,
<filipe.c.maia@gmail.com>, <yangerkun@huawei.com>,
<yi.zhang@huawei.com>
Subject: Re: [PATCH v2 2/3] md: allow configuring logical_block_size
Date: Thu, 31 Jul 2025 01:36:15 -0400 [thread overview]
Message-ID: <yq1zfcleyqv.fsf@ca-mkp.ca.oracle.com> (raw)
In-Reply-To: <20250719083119.1068811-3-linan666@huaweicloud.com> (linan's message of "Sat, 19 Jul 2025 16:31:18 +0800")
> Simply restricting larger-LBS disks is inflexible. In some scenarios,
> only disks with 512 LBS are available currently, but later, disks with
> 4k LBS may be added to the array.
Having to have the foresight to preemptively configure a larger logical
block size at creation time also seems somewhat inflexible :)
In general I am not a big fan of mixing devices with different
properties. I have regretted stacking the logical block size on several
occasions.
I am also concerned about PI breaking if the logical block size facing
upwards does not match the actual logical block size of the component
devices below. In theory it should work with the PI interval exponent
but it is something that needs to be tested.
What if the MD device's configured logical block size is larger than the
physical block size of the underlying devices? Then we'll end up
reporting a logical block size larger than the physical block size. Ugh.
Oh, and what about atomics?
--
Martin K. Petersen
next prev parent reply other threads:[~2025-07-31 5:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-19 8:31 [PATCH v2 0/3] make logical_block_size configurable linan666
2025-07-19 8:31 ` [PATCH v2 1/3] md: prevent adding disks with larger logical_block_size to active arrays linan666
2025-07-31 5:01 ` Martin K. Petersen
2025-07-19 8:31 ` [PATCH v2 2/3] md: allow configuring logical_block_size linan666
2025-07-31 5:36 ` Martin K. Petersen [this message]
2025-07-31 7:02 ` Yu Kuai
2025-07-19 8:31 ` [PATCH v2 3/3] md: Fix the return value of mddev_stack_new_rdev linan666
2025-07-31 5:01 ` Martin K. Petersen
2025-08-25 1:26 ` Li Nan
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