[yocto] Does my build disk's filesystem make a difference?

[Darren Hart]

On 01/06/2012 04:01 PM, Joshua Lock wrote:
> On 06/01/12 15:53, Jeff Osier-Mixon wrote:
>> I am creating a Yocto Project build system. For various reasons, it is a
>> dual-boot system, win7 & linux (probably mint 12, haven't decided). I
>> have a primary boot disk with both operating systems and a large
>> secondary disk to use for build trees etc.
>>
>> Does the filesystem on the big secondary disk matter? Ideally I would

Yes, it matters a great deal. Many of the features we use to ensure data
integrity and accounting slow down performance. I use a separate ext4
RAID 0 array for builds (and only for builds and other data that can be
easily recreated). I mount it without a journal and with noatime. This
significantly reduces the overhead of the filesystem and increases
performance considerably - at the cost of higher risk of data loss in
the event of an unclean shutdown.

>> like to be able to get to the large data disk from both operating
>> systems. That would necessitate NTFS, as win7 does not speak ext4
>> reliably, but I don't want to slow my builds down.

No way. See below for details.

> 
> Erk! I'm not familiar with NTFS but the thought of this scares me, I 
> expect you'd be opening yourself up to a world of hurt as:
> 
> a) NTFS isn't a first class citizen of Linux.
> b) according to wikipedia NTFS has a 255 character filename limit - I 
> don't know for certain this is a problem but I wouldn't be surprised if 
> it is.

In kernel NTFS only has experimental write support, and only to
overwrite existing files without changing their file size.

NTFS-3G provides a userspace filesystem implementation with more
features, but I'd bet my house on the performance being abysmal for builds.

--
Darren

> 
> Will you be storing anything on the disk that isn't build related? If 
> you anticipate doing a lot of builds you really want to a) use a 
> filesystem that is Linux native and b) tweak the filesystem to reduce 
> the number of writes made.
> 
> If you just want/need to be able to look at the build system pieces 
> under WinOS then you could try:
> http://www.ext2fsd.com/
> 
> Cheers,
> Joshua

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel