Mag Gam | 10 May 2011 00:40
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Re: Using stride on non-RAID

Are stride settings needed for Hardware RAID devices?

For example, if I do a RAID 5 on a HP-P800 I get a 9.1TB filesystem.
Should I worry about stride in that case?

On Wed, Mar 16, 2011 at 2:02 PM, David Shaw <dshaw <at> jabberwocky.com> wrote:
> On Mar 15, 2011, at 6:53 PM, Eric Sandeen wrote:
>
>> On 3/15/11 5:42 PM, David Shaw wrote:
>>> Hello,
>>>
>>> I understand the need for a proper stride setting when formatting a
>>> filesystem on a RAID device.  However, is there any problem in using
>>> a stride setting when formatting a filesystem on a regular non-RAID,
>>> non-SSD, just plain-vanilla-single-disk block device?  I'm sure there
>>> isn't any benefit to it, but I'm curious if there is any harm.
>>>
>>> The reason I ask is I'm looking at some code here that can be used on
>>> either RAID or non-RAID devices.  The stride setting it has is
>>> correct for the particular RAID setup it is intended for, but it also
>>> uses those settings when formatting a non-RAID device.
>>>
>>> David
>>
>> just FWIW, recent kernels & e2fsprogs will just automatically pick
>> stride based on storage geometry - for md/lvm at least, and for
>> scsi devices that export this geometry as well.
>>
>> ext4 has a little stripe-awareness in its allocator; otherwise, stride
>> just staggers bitmap starts so they don't all end up on the same spindle; [1]
(Continue reading)

Eric Sandeen | 10 May 2011 01:03
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Re: Using stride on non-RAID

On 5/9/11 5:40 PM, Mag Gam wrote:
> Are stride settings needed for Hardware RAID devices?
> 
> For example, if I do a RAID 5 on a HP-P800 I get a 9.1TB filesystem.
> Should I worry about stride in that case?

stride is useful so that you don't end up with metadata hotspots on a single disk.  this is true whether the
disks are raided together in hardware or in software, I think.

-Eric

> 
> On Wed, Mar 16, 2011 at 2:02 PM, David Shaw <dshaw <at> jabberwocky.com> wrote:
>> On Mar 15, 2011, at 6:53 PM, Eric Sandeen wrote:
>>
>>> On 3/15/11 5:42 PM, David Shaw wrote:
>>>> Hello,
>>>>
>>>> I understand the need for a proper stride setting when formatting a
>>>> filesystem on a RAID device.  However, is there any problem in using
>>>> a stride setting when formatting a filesystem on a regular non-RAID,
>>>> non-SSD, just plain-vanilla-single-disk block device?  I'm sure there
>>>> isn't any benefit to it, but I'm curious if there is any harm.
>>>>
>>>> The reason I ask is I'm looking at some code here that can be used on
>>>> either RAID or non-RAID devices.  The stride setting it has is
>>>> correct for the particular RAID setup it is intended for, but it also
>>>> uses those settings when formatting a non-RAID device.
>>>>
>>>> David
(Continue reading)

Amey | 16 May 2011 15:12
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How to mount ext3 root partition with noatime and ro options at boot-time

Hi all,

        I was trying to mount root-partition which is ext3 partition with noatime and ro option. I included "ro" in the kernel command line  But for mounting it with "noatime" option when I searched for some solution I came across a patch 

                 http://lkml.org/lkml/2007/8/5/38
 
        But after applying this patch and including option "noatime" in kernel command line , kernel by default mounts all the partition with "noatime" option which is not my requirement. I just want to mount root partition with ro and noatime option and other partitions with atime option at boottime only. So please help me in this regard.

        Thanking you all in advance.

Cheers,
AM

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Christian Kujau | 17 May 2011 22:10
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Re: How to mount ext3 root partition with noatime and ro options at boot-time

On Mon, 16 May 2011 at 18:42, Amey wrote:
>         I was trying to mount root-partition which is ext3 partition with
> noatime and ro option. I included "ro" in the kernel command line  But for
> mounting it with "noatime" option when I searched for some solution I came

Use tune2fs(8) to set default mount options for this partition. Or use the 
"rootflags=" bootparameter, e.g. rootflags=noatime,ro for setting noatime 
& readonly for the root filesystem.

HTH,
Christian.
--

-- 
BOFH excuse #110:

The rolling stones concert down the road caused a brown out
Stephen Samuel | 18 May 2011 05:13

Re: How to mount ext3 root partition with noatime and ro options at boot-time

So, if you mount the system ro, then why do you even need noatime -- since atime can't be updated at all if you're not writing to the filesystem.

On Tue, May 17, 2011 at 1:10 PM, Christian Kujau <lists <at> nerdbynature.de> wrote:
On Mon, 16 May 2011 at 18:42, Amey wrote:
>         I was trying to mount root-partition which is ext3 partition with
> noatime and ro option. I included "ro" in the kernel command line  But for
> mounting it with "noatime" option when I searched for some solution I came

Use tune2fs(8) to set default mount options for this partition. Or use the
"rootflags=" bootparameter, e.g. rootflags=noatime,ro for setting noatime
& readonly for the root filesystem.

HTH,
Christian.
--
BOFH excuse #110:

The rolling stones concert down the road caused a brown out

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Christian Kujau | 18 May 2011 05:16
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Re: How to mount ext3 root partition with noatime and ro options at boot-time

On Tue, 17 May 2011 at 20:13, Stephen Samuel wrote:
> So, if you mount the system ro, then why do you even need noatime -- since
> atime can't be updated at all if you're not writing to the filesystem.

Hehe, good point :-)

C.
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Gmane