On 8/21/2012 9:51 AM, Miquel van Smoorenburg wrote:
> On 08/20/2012 01:34 AM, Stan Hoeppner wrote:
>> I'm glad you jumped in David. You made a critical statement of fact
>> below which clears some things up. If you had stated it early on,
>> before Miquel stole the thread and moved it to LKML
On 08/20/2012 01:34 AM, Stan Hoeppner wrote:
I'm glad you jumped in David. You made a critical statement of fact
below which clears some things up. If you had stated it early on,
before Miquel stole the thread and moved it to LKML proper, it would
have short circuited a lot of this discussion.
On 8/21/2012 9:51 AM, Miquel van Smoorenburg wrote:
On 08/20/2012 01:34 AM, Stan Hoeppner wrote:
I'm glad you jumped in David. You made a critical statement of fact
below which clears some things up. If you had stated it early on,
before Miquel stole the thread and moved it to LKML proper,
On 08/20/2012 01:34 AM, Stan Hoeppner wrote:
I'm glad you jumped in David. You made a critical statement of fact
below which clears some things up. If you had stated it early on,
before Miquel stole the thread and moved it to LKML proper, it would
have short circuited a lot of this discussion.
On 20/08/2012 02:01, NeilBrown wrote:
On Sun, 19 Aug 2012 18:34:28 -0500 Stan Hoeppner
wrote:
Since we are trying to set the record straight
md/RAID6 must read all devices in a RMW cycle.
md/RAID6 must read all data devices (i.e. not parity devices) which it is not
going to write to,
On 20/08/2012 02:01, NeilBrown wrote:
On Sun, 19 Aug 2012 18:34:28 -0500 Stan Hoeppner s...@hardwarefreak.com
wrote:
Since we are trying to set the record straight
md/RAID6 must read all devices in a RMW cycle.
md/RAID6 must read all data devices (i.e. not parity devices) which it is
On Sun, 19 Aug 2012 18:34:28 -0500 Stan Hoeppner
wrote:
> On 8/19/2012 9:01 AM, David Brown wrote:
> > I'm sort of jumping in to this thread, so my apologies if I repeat
> > things other people have said already.
>
> I'm glad you jumped in David. You made a critical statement of fact
> below
On 8/19/2012 9:01 AM, David Brown wrote:
> I'm sort of jumping in to this thread, so my apologies if I repeat
> things other people have said already.
I'm glad you jumped in David. You made a critical statement of fact
below which clears some things up. If you had stated it early on,
before
On 8/19/2012 9:01 AM, David Brown wrote:
I'm sort of jumping in to this thread, so my apologies if I repeat
things other people have said already.
I'm glad you jumped in David. You made a critical statement of fact
below which clears some things up. If you had stated it early on,
before
On Sun, 19 Aug 2012 18:34:28 -0500 Stan Hoeppner s...@hardwarefreak.com
wrote:
On 8/19/2012 9:01 AM, David Brown wrote:
I'm sort of jumping in to this thread, so my apologies if I repeat
things other people have said already.
I'm glad you jumped in David. You made a critical statement of
On 08/17/2012 09:31 AM, Stan Hoeppner wrote:
On 8/16/2012 4:50 PM, Miquel van Smoorenburg wrote:
I did a simple test:
* created a 1G partition on 3 seperate disks
* created a md raid5 array with 512K chunksize:
mdadm -C /dev/md0 -l 5 -c $((1024*512)) -n 3 /dev/sdb1 /dev/sdc1
/dev/sdd1
* ran
On 8/16/2012 4:50 PM, Miquel van Smoorenburg wrote:
> On 16-08-12 1:05 PM, Stan Hoeppner wrote:
>> On 8/15/2012 6:07 PM, Miquel van Smoorenburg wrote:
>>> Ehrm no. If you modify, say, a 4K block on a RAID5 array, you just have
>>> to read that 4K block, and the corresponding 4K block on the
>>>
On 8/16/2012 4:50 PM, Miquel van Smoorenburg wrote:
On 16-08-12 1:05 PM, Stan Hoeppner wrote:
On 8/15/2012 6:07 PM, Miquel van Smoorenburg wrote:
Ehrm no. If you modify, say, a 4K block on a RAID5 array, you just have
to read that 4K block, and the corresponding 4K block on the
parity drive,
On 08/17/2012 09:31 AM, Stan Hoeppner wrote:
On 8/16/2012 4:50 PM, Miquel van Smoorenburg wrote:
I did a simple test:
* created a 1G partition on 3 seperate disks
* created a md raid5 array with 512K chunksize:
mdadm -C /dev/md0 -l 5 -c $((1024*512)) -n 3 /dev/sdb1 /dev/sdc1
/dev/sdd1
* ran
On 16-08-12 1:05 PM, Stan Hoeppner wrote:
On 8/15/2012 6:07 PM, Miquel van Smoorenburg wrote:
Ehrm no. If you modify, say, a 4K block on a RAID5 array, you just have
to read that 4K block, and the corresponding 4K block on the
parity drive, recalculate parity, and write back 4K of data and 4K
On 8/15/2012 6:07 PM, Miquel van Smoorenburg wrote:
> In article you write:
>> It's time to blow away the array and start over. You're already
>> misaligned, and a 512KB chunk is insanely unsuitable for parity RAID,
>> but for a handful of niche all streaming workloads with little/no
>> rewrite,
On Wed, 15 Aug 2012 18:50:44 -0500
Stan Hoeppner wrote:
> TTBOMK there are two, and only two, COW filesystems in existence: ZFS and
> BTRFS.
There is also NILFS2: http://www.nilfs.org/en/
And in general, any https://en.wikipedia.org/wiki/Log-structured_file_system
is COW by design, but afaik
On Wed, 15 Aug 2012 18:50:44 -0500
Stan Hoeppner s...@hardwarefreak.com wrote:
TTBOMK there are two, and only two, COW filesystems in existence: ZFS and
BTRFS.
There is also NILFS2: http://www.nilfs.org/en/
And in general, any https://en.wikipedia.org/wiki/Log-structured_file_system
is COW
On 8/15/2012 6:07 PM, Miquel van Smoorenburg wrote:
In article xs4all.502c1c01.1040...@hardwarefreak.com you write:
It's time to blow away the array and start over. You're already
misaligned, and a 512KB chunk is insanely unsuitable for parity RAID,
but for a handful of niche all streaming
On 16-08-12 1:05 PM, Stan Hoeppner wrote:
On 8/15/2012 6:07 PM, Miquel van Smoorenburg wrote:
Ehrm no. If you modify, say, a 4K block on a RAID5 array, you just have
to read that 4K block, and the corresponding 4K block on the
parity drive, recalculate parity, and write back 4K of data and 4K
On Wed, Aug 15, 2012 at 4:50 PM, Stan Hoeppner wrote:
> On 8/15/2012 5:10 PM, Andy Lutomirski wrote:
>> On Wed, Aug 15, 2012 at 3:00 PM, Stan Hoeppner
>> wrote:
>>> On 8/15/2012 12:57 PM, Andy Lutomirski wrote:
On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
wrote:
> On 15/08/2012
On 8/15/2012 5:10 PM, Andy Lutomirski wrote:
> On Wed, Aug 15, 2012 at 3:00 PM, Stan Hoeppner wrote:
>> On 8/15/2012 12:57 PM, Andy Lutomirski wrote:
>>> On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
>>> wrote:
On 15/08/2012 01:49, Andy Lutomirski wrote:
>
> If I do:
> # dd
In article you write:
>It's time to blow away the array and start over. You're already
>misaligned, and a 512KB chunk is insanely unsuitable for parity RAID,
>but for a handful of niche all streaming workloads with little/no
>rewrite, such as video surveillance or DVR workloads.
>
>Yes, 512KB is
On Wed, Aug 15, 2012 at 3:00 PM, Stan Hoeppner wrote:
> On 8/15/2012 12:57 PM, Andy Lutomirski wrote:
>> On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
>> wrote:
>>> On 15/08/2012 01:49, Andy Lutomirski wrote:
If I do:
# dd if=/dev/zero of=/dev/md0p1 bs=8M
>>>
>>> [...]
>>>
On 8/15/2012 12:57 PM, Andy Lutomirski wrote:
> On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
> wrote:
>> On 15/08/2012 01:49, Andy Lutomirski wrote:
>>>
>>> If I do:
>>> # dd if=/dev/zero of=/dev/md0p1 bs=8M
>>
>> [...]
>>
>>> It looks like md isn't recognizing that I'm writing whole stripes
On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
wrote:
> On 15/08/2012 01:49, Andy Lutomirski wrote:
>>
>> If I do:
>> # dd if=/dev/zero of=/dev/md0p1 bs=8M
>
> [...]
>
>> It looks like md isn't recognizing that I'm writing whole stripes when
>> I'm in O_DIRECT mode.
>
>
> I see your md device is
On 15/08/2012 01:49, Andy Lutomirski wrote:
If I do:
# dd if=/dev/zero of=/dev/md0p1 bs=8M
[...]
It looks like md isn't recognizing that I'm writing whole stripes when
I'm in O_DIRECT mode.
I see your md device is partitioned. Is the partition itself stripe-aligned?
Cheers,
John.
--
To
On 15/08/2012 01:49, Andy Lutomirski wrote:
If I do:
# dd if=/dev/zero of=/dev/md0p1 bs=8M
[...]
It looks like md isn't recognizing that I'm writing whole stripes when
I'm in O_DIRECT mode.
I see your md device is partitioned. Is the partition itself stripe-aligned?
Cheers,
John.
--
To
On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
john.robin...@anonymous.org.uk wrote:
On 15/08/2012 01:49, Andy Lutomirski wrote:
If I do:
# dd if=/dev/zero of=/dev/md0p1 bs=8M
[...]
It looks like md isn't recognizing that I'm writing whole stripes when
I'm in O_DIRECT mode.
I see your
On 8/15/2012 12:57 PM, Andy Lutomirski wrote:
On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
john.robin...@anonymous.org.uk wrote:
On 15/08/2012 01:49, Andy Lutomirski wrote:
If I do:
# dd if=/dev/zero of=/dev/md0p1 bs=8M
[...]
It looks like md isn't recognizing that I'm writing whole
On Wed, Aug 15, 2012 at 3:00 PM, Stan Hoeppner s...@hardwarefreak.com wrote:
On 8/15/2012 12:57 PM, Andy Lutomirski wrote:
On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
john.robin...@anonymous.org.uk wrote:
On 15/08/2012 01:49, Andy Lutomirski wrote:
If I do:
# dd if=/dev/zero
In article xs4all.502c1c01.1040...@hardwarefreak.com you write:
It's time to blow away the array and start over. You're already
misaligned, and a 512KB chunk is insanely unsuitable for parity RAID,
but for a handful of niche all streaming workloads with little/no
rewrite, such as video
On 8/15/2012 5:10 PM, Andy Lutomirski wrote:
On Wed, Aug 15, 2012 at 3:00 PM, Stan Hoeppner s...@hardwarefreak.com wrote:
On 8/15/2012 12:57 PM, Andy Lutomirski wrote:
On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
john.robin...@anonymous.org.uk wrote:
On 15/08/2012 01:49, Andy Lutomirski
On Wed, Aug 15, 2012 at 4:50 PM, Stan Hoeppner s...@hardwarefreak.com wrote:
On 8/15/2012 5:10 PM, Andy Lutomirski wrote:
On Wed, Aug 15, 2012 at 3:00 PM, Stan Hoeppner s...@hardwarefreak.com
wrote:
On 8/15/2012 12:57 PM, Andy Lutomirski wrote:
On Wed, Aug 15, 2012 at 4:50 AM, John Robinson
On 2012-08-15 09:12 Andy Lutomirski Wrote:
>Ubuntu's 3.2.0-27-generic. I can test on a newer kernel tomorrow.
I guess maybe miss the blk_plug function.
Can you add this patch and retest.
Move unplugging for direct I/O from around ->direct_IO() down to
do_blockdev_direct_IO(). This implicitly
Ubuntu's 3.2.0-27-generic. I can test on a newer kernel tomorrow.
--Andy
On Tue, Aug 14, 2012 at 6:07 PM, kedacomkernel wrote:
> On 2012-08-15 08:49 Andy Lutomirski Wrote:
>>If I do:
>># dd if=/dev/zero of=/dev/md0p1 bs=8M
>>then iostat -m 5 says:
>>
>>avg-cpu: %user %nice %system %iowait
On 2012-08-15 08:49 Andy Lutomirski Wrote:
>If I do:
># dd if=/dev/zero of=/dev/md0p1 bs=8M
>then iostat -m 5 says:
>
>avg-cpu: %user %nice %system %iowait %steal %idle
> 0.000.00 26.88 35.270.00 37.85
>
>Device:tpsMB_read/sMB_wrtn/sMB_read
On 2012-08-15 08:49 Andy Lutomirski l...@amacapital.net Wrote:
If I do:
# dd if=/dev/zero of=/dev/md0p1 bs=8M
then iostat -m 5 says:
avg-cpu: %user %nice %system %iowait %steal %idle
0.000.00 26.88 35.270.00 37.85
Device:tpsMB_read/sMB_wrtn/s
Ubuntu's 3.2.0-27-generic. I can test on a newer kernel tomorrow.
--Andy
On Tue, Aug 14, 2012 at 6:07 PM, kedacomkernel kedacomker...@gmail.com wrote:
On 2012-08-15 08:49 Andy Lutomirski l...@amacapital.net Wrote:
If I do:
# dd if=/dev/zero of=/dev/md0p1 bs=8M
then iostat -m 5 says:
avg-cpu:
On 2012-08-15 09:12 Andy Lutomirski l...@amacapital.net Wrote:
Ubuntu's 3.2.0-27-generic. I can test on a newer kernel tomorrow.
I guess maybe miss the blk_plug function.
Can you add this patch and retest.
Move unplugging for direct I/O from around -direct_IO() down to
do_blockdev_direct_IO().
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