really strange ext4 behavior
Michał Piotrowski
mkkp4x4 at gmail.com
Sat Feb 12 22:31:41 UTC 2011
Hi,
W dniu 12 lutego 2011 23:19 użytkownik Ric Wheeler
<rwheeler at redhat.com> napisał:
> On 02/12/2011 05:12 PM, Michał Piotrowski wrote:
>>
>> Hi,
>>
>> I added a disc to my box. I wanted to use ext4. I run fs_mark to test
>> speed, to my surprise I heard a really strange noises.
>>
>> It's very strange because the drive is new
>> 9 Power_On_Hours 0x0032 100 100 000 Old_age
>> Always - 12
>>
>>
>> # fs_mark -d test/
>> [..]
>> FSUse% Count Size Files/sec App Overhead
>> 0 1000 51200 22.8 54347
>>
>> I decided to create an ext3 file system on this drive and everything works
>> fine.
>>
>> # fs_mark -d test/
>> [..]
>> FSUse% Count Size Files/sec App Overhead
>> 0 1000 51200 103.7 57229
>>
>> When I mount this ext3 fs as ext4 and run fs_mark I hear strange sounds
>> again.
>>
>> I use F14 and self compiled kernel from rawhide 2.6.37-1.fc14.x86_64 +
>> e2fsprogs-1.41.14-2.fc14.x86_64.
>>
>> I mount ecryptfs on top of this file system.
>>
>> Does anyone know what might be causing this strange ext4 behavior?
>>
>
> Hi Michael,
>
> fs_mark run a fsync heavy test. What you might be hearing is the impact of
> the fsync's. ext4 defaults to using "write barriers" enabled, ext3 does not.
> Without write barriers, those fsync push data from the box to the write
> cache on the drive only. With barriers, the disk will flush that cache to
> the platter, so the platter moves and you probably hear the head, etc.
>
> You can test if this is the cause by mouting ext4 with "nobarrier" to see if
> the noise goes away.
I mounted fs with nobarrier and now it works just like ext3. Thanks! This solves
the riddle :)
>
> Drives can be noisy, but occasionally, if they are over noisy (you hear
> chattering when writing), it might just be a bad drive that has trouble
> settling the heads after a seek.
>
> You might want to check with:
>
> smartctl -a /dev/sda
>
> To look for errors that the drive reports.
I regularly test all drives that I use, this one is irreproachable
1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail
Always - 0
[..]
Num Test_Description Status Remaining
LifeTime(hours) LBA_of_first_error
# 1 Extended offline Completed without error 00% 10 -
>
> Good luck!
>
> Ric
>
>
Thanks for your help!
--
Best regards,
Michal
http://eventhorizon.pl/
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