From: unruh on
["Followup-To:" header set to alt.os.linux.]
On 2010-04-14, Robert Heller <heller(a)deepsoft.com> wrote:
> At Wed, 14 Apr 2010 16:11:21 GMT unruh <unruh(a)wormhole.physics.ubc.ca> wrote:
>
>>
>> On 2010-04-14, J G Miller <miller(a)yoyo.ORG> wrote:
>> > On Wed, 14 Apr 2010 15:00:17 +0000, Unruh asked:
>> >
>> >> Is there a difference between that and 83 Linux ?
>> >
>> > Yes.
>> >
>> > 83 is Linux (as in ext2/ext3/ext4) and fd is Linux raid auto.
>> >
>> > If the partition type is not correctly set, then the Linux kernel
>> > will not have the correct information about which partitions are
>> > being used for RAID, and therefore will be unable to auto-detect
>> > and automatically manage the RAID array.
>>
>> Thanks. I had not even realised that type fd existed.
>>
>>
>> >
>> > From <http://en.gentoo-wiki.COM/wiki/RAID/Software>
>> >
>> > QUOTE
>> >
>> > When you partition your disks, make sure that your partitions use fd
>> > (Linux RAID autodetect) as Partition Type instead of the default 83
>> > (Linux native) or 82 (swap).
>> >
>> > UNQUOTE
>> >
>> > Also, I hope that when you create the file system on your RAID array,
>> > you use the most suitable parameters (stride, stride_width) for
>> > the type of RAID in order to optimize performance.
>>
>> No idea what that means. I will read up on it. Thanks.
>>
>>
>> >
>> > See calculator at <http://busybox.NET/~aldot/mkfs_stride.html>
>>
>> Unfortunately I do not understand the inputs (Raid Chunck Size, number
>> of filesystem blocks)
>
> The Raid Chunck Size is an input to mdadm when you create the array. It
> is 64K by default. The number of filesystem blocks is the number of
> blocks in the file system, it is the number of bytes in the file system
> divided by the block size (mke2fs ... -b bs ...).

Except on that web page, the "default" is 4 and the question is
number of filesystem blocks (in KiB)
which makes no sensei- I suppose this must mean the block size, not the
number.



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