On 2/13/11 12:29 PM, Dennis Jacobfeuerborn wrote: > On 02/12/2011 11:52 PM, Ric Wheeler wrote: >> On 02/12/2011 05:31 PM, Michał Piotrowski wrote: >>> Hi, >>> >>> W dniu 12 lutego 2011 23:19 użytkownik Ric Wheeler >>> <rwheeler@xxxxxxxxxx> 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 :) >>> >> >> Good to hear that it worked! >> >> Note that the barrier code makes your data safer, so you should run with it on >> by default (unless you really don't care about the file system). > > If ext3 was running fine without barriers for all these years why is this > such a problem with ext4? Does ext4 do something differently that barriers > are now required? barriers are always required for integrity if you have a volatile write cache; this is true for ext3 as well. You may not see problems on every power loss, but eventually you will. The problems are often found after the fact, with a subsequent runtime or fsck error, so the culprit may not be immediately obvious. -Eric > Regards, > Dennis -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
