Re: Do I have to do anything to make sure ext4lazyinit works as being advertised ?
On Wed, Feb 01, 2017 at 12:46:48AM +0530, shirish शिरीष wrote:
> Hi all,
>
> Warning - is a bit of a long read.
>
> >From what all I read and understood, ext4lazyinit simply makes you
> start using the hdd without creating all the inodes for your system.
> The only way that you know ext4lazyinit is working is when you see it
> via iotop. But when using debian-installer is there something I could
> do, umm...some switch or something to make sure that ext4lazyinit
> works in the background ?
>
> To elaborate it a bit further. Let's say I get one of those monster
> drives (which are probably insanely expensive atm)
> https://www.hgst.com/products/hard-drives/ultrastar-he12
>
> While I would go bankrupt if I got this sort of hdd today, such drives
> were probably is the reason why ext4lazyinit was invented.
>
> FWIW I would be working with a 3/4 TB HDD in the near future hence
> want to be ready before-hand.
>
> Now let's say I use the current debian-installer for stretch - say
> either the net installer or the CD version -
>
> http://cdimage.debian.org/cdimage/stretch_di_rc1/amd64/iso-cd/debian-stretch-DI-rc1-amd64-netinst.iso
>
> http://cdimage.debian.org/cdimage/stretch_di_rc1/amd64/iso-cd/debian-stretch-DI-rc1-amd64-xfce-CD-1.iso
>
> The reason to use ext4lazyinit is light at my end is pretty erratic
> and many a times a UPS is not available.
>
> Having ext4lazyinit would be great if I am able to finish the
> installation fast and let it do inode creation on future boot-ups
> while I do the rest of the configuration, setting up the machine.
> updating/upgrading packages etc.
>
> Now I have few queries -
>
> a. Are my assumptions wrong ?
About the doing the init on a future boot, yes you are wrong.
> b. I don't know how much part of this question is debian-kernel
> related and how much of it is debian-installer related hence sending
> the mail to both the lists ?
>
> AIUI ext4lazyinit is a filesystem utility created for kernel during
> the end of 2.6.32.x series, hence couple of years ago - hence it
> relates to debian-kernel the most.
2.6.37 apparently.
> Current kernel is 4.9 in Debian stretch -
>
> [$] uname -r
>
> 4.9.0-1-amd64
>
> I do not know much of debian-installer support is/was needed to make
> sure the feature works as desired - hence the need to also mail
> debian-boot.
>
> I ask as I still have memories of 2-3 years sitting all night long at
> friend's places who had access to an offline UPS to partition, format
> and then do the installation. The partitioning and formatting taking
> the most time even with the Large-File Support under ext3.
>
> Looking forward to know.
I believe it is on by default. However, the lazy init takes
place in the background on first mount (so that means during
the install), not some later boot. It apparently will use
up to 16MB/s for initializing in the background according to
https://www.thomas-krenn.com/en/wiki/Ext4_Filesystem
I suspect it is already doing the best you are going to get.
--
Len Sorensen
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