linux-ext4 - Re: [RFC] store RAID stride in superblock

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Message-ID: <46559E04.5060002@clusterfs.com>
Date:	Thu, 24 May 2007 19:45:32 +0530
From:	Rupesh Thakare <rupesh@...sterfs.com>
To:	Theodore Ts'o <tytso@....edu>
CC:	Andreas Dilger <adilger@...sterfs.com>, linux-ext4@...r.kernel.org
Subject: Re: [RFC] store RAID stride in superblock

Hello,
I've added "s_raid_stripe_width" parameter in superblock.
I've also incorporated "s_raid_stride" and "s_raid_stripe_width" 
parameters in tune2fs.
The new options can be specified using  '-E options' in both mke2fs and 
tune2fs.
Both the Man pages (mke2fs and tune2fs) are updated accordingly.
Patch is attached herewith.
Thanks,
Rupesh.

Andreas Dilger wrote:
> On May 22, 2007  01:22 +0530, Kalpak Shah wrote:
>   
>>         __u16   s_raid_stride;          /* RAID stride */
>> -       __u16   s_pad;                  /* Padding */
>> +       __u16   s_mmp_interval;         /* Wait for # seconds in MMP
>> checking */
>> +       __u64   s_mmp_block;            /* Block for multi-mount protection
>> */
>>     
>
> Ted, I just noticed this updated patch w.r.t. your recent s_raid_stride
> addition.  I also want to have a separate parameter for "s_raid_stripe_width"
> which is normally N * s_raid_stride, where N is the number of disks in a
> RAID 5 N+1 (or RAID 6 N+2) parity stripe.  This is for delalloc+mballoc to
> allow it to align and size new allocations so that writes do not impose
> read-modify-write overhead on the RAID stripes.
>
> My understanding from the code is that s_raid_stride is to put the bitmaps
> for different groups on different disks to avoid always having a single
> disk busy with bitmap updates.
>
>
> Cheers, Andreas
> --
> Andreas Dilger
> Principal Software Engineer
> Cluster File Systems, Inc.
>
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View attachment "e2fsprogs_stride.patch" of type "text/x-patch" (10109 bytes)