From: Zdenek Kabelac <zkabelac@redhat.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] Why LVM metadata locations are not properly aligned
Date: Thu, 21 Apr 2016 15:22:26 +0200 [thread overview]
Message-ID: <5718D412.2020303@redhat.com> (raw)
In-Reply-To: <5718A369.4060103@redhat.com>
On 21.4.2016 11:54, Zdenek Kabelac wrote:
> On 21.4.2016 06:08, Ming-Hung Tsai wrote:
>> Hi,
>>
>>
>> 1. The metadata locations (raw_locn::offset) are not properly aligned.
>> Function _aligned_io() requires the IO to be logical-block aligned,
>> but metadata locations returned by next_rlocn_offset() are 512-byte
>> aligned.
>> If a device's logical block size is greater than 512b, then LVM need to use
>> bounce buffer to do the IO.
>> How about setting raw_locn::offset to logical-block boundary?
>> (or max(logical_block_size, physical_block_size) for 512-byte logical-/4KB
>> physical-block drives?)
>
> This looks like a bug - lvm2 should start to write metadata always on physical
> block aligned position.
Hi
I've opened RFE BZ for this one - https://bugzilla.redhat.com/1329234
It's not completely trivial to fix this in a backward compatible way - but I'm
mostly 100% sure it's not cause your 10s delay unless.
Regards
Zdenek
next prev parent reply other threads:[~2016-04-21 13:22 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-21 4:08 [linux-lvm] Why LVM metadata locations are not properly aligned Ming-Hung Tsai
2016-04-21 9:54 ` Zdenek Kabelac
2016-04-21 13:22 ` Zdenek Kabelac [this message]
2016-04-22 8:43 ` Ming-Hung Tsai
2016-04-22 9:49 ` Zdenek Kabelac
2016-04-21 10:11 ` Alasdair G Kergon
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