[Novalug] ext4 vs. ext3 vs. ext2

Richard Ertel richard.ertel@gmail.com
Mon Sep 7 19:40:46 EDT 2009


fair enough. so is 'noatime' and 'dir_index' just options in fstab?

On Mon, Sep 7, 2009 at 18:43, James Ewing Cottrell
3rd<JECottrell3@comcast.net> wrote:
> No, go with dir_index and noatime.
>
> After struggling with systems where /mail/username has to be hashed into
> /mail/use/er/username, for large numbers of users, it's nice to be able to
> store hundreds or thousands of entries in a directory.
>
> And why do you need ANY atime updating?
>
> JIM
>
> Richard Ertel wrote:
>>
>> thanks for all the replies, everyone. based on all this info, i think
>> i'll go with ext3 with relatime, but not with dir_index, as i have all
>> my files organized into many folders, not many files per folder. and
>> i'm more familiar with ext3 than with xfs, so i think i'll stay with
>> that i know.
>>
>> On Mon, Sep 7, 2009 at 17:28, Gregory Maxwell<gmaxwell@gmail.com> wrote:
>>>
>>> On Mon, Sep 7, 2009 at 5:10 PM, Jon LaBadie<novalugml@jgcomp.com> wrote:
>>>>
>>>> On Mon, Sep 07, 2009 at 05:01:18PM -0400, Gregory Maxwell wrote:
>>>>>
>>>>> Atime can be really handy though. For example, say you're looking for
>>>>> an old file that you know you read in the last week but you do not
>>>>> know the name with atime enabled you can find it with find.  Even
>>>>> though I find atime useful the cost of reads generating disk writes is
>>>>> high enough that I disable it on my systems.
>>>>>
>>>> Does anyone know of an objective study of the value of noatime?
>>>
>>> This isn't something that really requires a lot of study:
>>>
>>> Without noatime regular reads of files result in writes to update the
>>> metadata.  If you have a read-mostly workload and your working set
>>> fits in ram your disk can sit spun-down if you enable noatime. Here
>>> it's a clear win.
>>>
>>> If you're not concerned with spinning down the disk— atime isn't
>>> updated for mmap or zero-copy which any high transaction rate app
>>> should be used for anyways. So it's not a big deal.
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