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HOWTO: Gentoo Diskless with ATA over Ethernet (AoE)
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Abraxa
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PostPosted: Sun Mar 12, 2006 11:18 am    Post subject: Reply with quote

Why is this thread in Desktop Environments? Someone should move this to the documentation forum, I reckon.

-Soeren
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VoVaN
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PostPosted: Mon Mar 20, 2006 2:14 pm    Post subject: Reply with quote

I'm going to try more efficient initramfs instead of initrd. Does anybody have any expiriences. As a bonus, it's possible to avoid blinking with bootsplash then. ;)
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VoVaN
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PostPosted: Mon Apr 24, 2006 8:22 am    Post subject: Reply with quote

Finally, I've successfully switched to initramfs... even shorter boot time and quicker application execution! I had some troubles during early boot. That was /sbin/hotplug, so that's necessary to disable it somehow (chmod 644) for the time of loading the kernel.
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ldc
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PostPosted: Tue Sep 18, 2007 7:31 pm    Post subject: Reply with quote

Just wanted to give some back after the initial idea from this thread :)

Here you go, a generic initramfs that should work for most distributions. The only thing is that it's only premade for x86_64 so if you have something else you will have to replace the busybox.static in there. (follow the guidelines)
http://bladerunner.mine.nu/

Some things in there are specific for my system, but it should still work on most systems with a minimal extra delay. (got a network card that takes 5-10 seconds before any traffic can actually pass on it.)

Hope it's useful for someone.
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VoVaN
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PostPosted: Wed Sep 19, 2007 5:27 am    Post subject: Reply with quote

2ldc: I switched using very small ~400K initramfs with busybox as well, because tftp transfers (in case of relatively big initramfs) are much slower then NFS or FTP for instance. Now I'm using lzma instead of bzip compressed kernel (patch http://www.udpcast.linux.lu/source.html) and lzma patched squashfs tools (http://www.squashfs-lzma.org/). It makes images smaller and improves decompression speed. Since the initial post I've made even some more improvements, but it looks like it's not very popular in our days or it's wrong place for posting, so I stopped any updates of this topic :(
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ldc
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PostPosted: Wed Sep 19, 2007 7:01 am    Post subject: Reply with quote

Hi VoVaN,

Cannot see how you can think that tftp is much slower than NFS or FTP?... Have done some tests in my setup here and with tftp i have been booting initramfs-images of around 40Mb within 3-4 seconds (+ decompression of course) while nfs have been up to around 10-15 seconds, maybe down to around 5-6 seconds with a idle NFS server.. I where using gPXE for that.
Have not tried using http or ftp so far, but i suspect that those also are affected by the amount of time it takes to init the connection before connecting. Only issue when i have seen when tftp has performed badly is when using a non-compatible tftp server that causes a real slowdown.

Have not really looked into improving decompression-speed since it's still so low that i cannot notice it when the image is this small (2Mb), but thanks for the hints, might be something to use for the HTPC ramdisk later on :)

Just some observations that i have made on the setup here.. And maybe not allot of people are using this just because the documentation is so scarce, or just to complicated for the average user. I would be glad to see some basic AoE support implemented in the gentoo initramfs, and it should be quite easy to get that into the generic initramfs, maybe even on the minimal install cd to allow for a install to a AoE disk.
All that's really needed here is: check for AoE in the kernel and if we are trying to boot against a AoE target, bring up all interfaces or atleast the one specified on the kernel-cmd-line, touch the discover, wait for AoE to complete the discovery process and continue with the init.

Probably gonna do some more stuff related to this in the near future so maybe i'll be able to post a good generic patch for genkernel to include this too.

But i got to say that i'm loving booting from a AoE target... Got 3Gb ram in the soe-server and it really boosts the disk-performance. (15 second for a find / -xdev with around 400k files when everything is in the targets buffercache). And planning to implement a GFS or OCFS2 shared volume via AoE soon too, but that needs more research, and some fix to access the disk via AoE on the actual target-system. Maybe i'll write a howto for all this later on too..
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VoVaN
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PostPosted: Wed Sep 19, 2007 8:05 am    Post subject: Reply with quote

ldc wrote:
Hi VoVaN,

Cannot see how you can think that tftp is much slower than NFS or FTP?... Have done some tests in my setup here and with tftp i have been booting initramfs-images of around 40Mb within 3-4 seconds (+ decompression of course) while nfs have been up to around 10-15 seconds, maybe down to around 5-6 seconds with a idle NFS server.. I where using gPXE for that.
Have not tried using http or ftp so far, but i suspect that those also are affected by the amount of time it takes to init the connection before connecting. Only issue when i have seen when tftp has performed badly is when using a non-compatible tftp server that causes a real slowdown.


I think the keyword here is gPXE. I didn't try gPXE (jet), but using intel PXE + PXELinux (tried a lot of PCI intel cards as well as onboard NIC's) makes tftp transfers really slow. I've done some research a while ago and found some proves concerning my point. BTW, could you explain your setup with gPXE?

ldc wrote:

Have not really looked into improving decompression-speed since it's still so low that i cannot notice it when the image is this small (2Mb), but thanks for the hints, might be something to use for the HTPC ramdisk later on :)


Probably I explained incorrectly, but it's not exactly "decompression speed" of initramfs image (it indeed not really noticeable), but reading LZMA compressed squashfs image via AoE is somehow about 30-50% faster then standard squashfs. As I mentioned briefly already, in my setup I'm using lzma compressed kernel (~1.2Mb instead of ~1.8Mb with bzip) with ~400kb initramfs (busybox for setting up root on initramfs and AoE based on kernel command line parameters), the rest is read-only squashfs image via AoE as well. Using root on initramfs (/tmp, /var/tmp and /var/log on initramfs as well) makes setup more flexible and _really_ improves boot times. It's even boots faster then if I would use just local hard drive on the same PC without any initramfs/squashfs)

ldc wrote:

Just some observations that i have made on the setup here.. And maybe not allot of people are using this just because the documentation is so scarce, or just to complicated for the average user. I would be glad to see some basic AoE support implemented in the gentoo initramfs, and it should be quite easy to get that into the generic initramfs, maybe even on the minimal install cd to allow for a install to a AoE disk.
All that's really needed here is: check for AoE in the kernel and if we are trying to boot against a AoE target, bring up all interfaces or atleast the one specified on the kernel-cmd-line, touch the discover, wait for AoE to complete the discovery process and continue with the init.

Probably gonna do some more stuff related to this in the near future so maybe i'll be able to post a good generic patch for genkernel to include this too.

But i got to say that i'm loving booting from a AoE target... Got 3Gb ram in the soe-server and it really boosts the disk-performance. (15 second for a find / -xdev with around 400k files when everything is in the targets buffercache). And planning to implement a GFS or OCFS2 shared volume via AoE soon too, but that needs more research, and some fix to access the disk via AoE on the actual target-system. Maybe i'll write a howto for all this later on too..


I've been thinking about it as well, but in my case it's GFS is useless (squashfs is readonly). It probably would be interesting using GFS+AoE instead of NFS (speed improvements?). Keep us informed, i'm interesting in all these kind on researches.
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ldc
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PostPosted: Sat Sep 22, 2007 11:08 am    Post subject: Reply with quote

VoVaN wrote:

I think the keyword here is gPXE. I didn't try gPXE (jet), but using intel PXE + PXELinux (tried a lot of PCI intel cards as well as onboard NIC's) makes tftp transfers really slow. I've done some research a while ago and found some proves concerning my point. BTW, could you explain your setup with gPXE?


Yea, i have seen that behaviour too, until i switched the tftp-server.. There are alot of network cards that has a problem with specific features but at atftp seems to be working good for most cards (and have tried it with intel too)


VoVaN wrote:

I've been thinking about it as well, but in my case it's GFS is useless (squashfs is readonly). It probably would be interesting using GFS+AoE instead of NFS (speed improvements?). Keep us informed, i'm interesting in all these kind on researches.


Will do... but have run into some road bumps :P
AoE dont support access to a locally shared AoE blade, and since i'm using lvol's for the disk-shares it's a bit of a problem to get access to 'virtual' disk.
I'm currently looking into switching from qaoed to one of the kernel-based AoE servers to be able to add local block-device support for the devices. Ie, instead of going via network for accessing the AoE disk i'm looking into adding support into the AoE server to display the shared disks locally that will bypass the network completely.
Have also started looking into OCFS2 (Oracle Cluster FS) since it requires a much simpler setup and some people i have talked to have recommended it to me since i mainly have lots of large (>100MB) files and OCFS2 should have much better performance, but have had some problems with fencing here due to the need of accessing the OCFS2 filesystem on the same machine that i have the disks, and since AoE where not able to share disks locally i tried it with iSCSI. Did work great as long as the load was low, but as soon as i tried maxing out the performance the client fenced due to heartbeat timeouts. Might have been better with AoE since it we much nicer to the network stack by not using tcp/ip connections.

And yea, the performance of GFS do seem to be better than NFS. See the following link for some tests.
http://web.bii.a-star.edu.sg/~james/fs_review/
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ldc
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PostPosted: Mon Sep 24, 2007 12:34 pm    Post subject: Reply with quote

Ignore the previous post grammatic errors... was quite tired when i wrote it :)

Have been in contact with the aoeserver owner since that was the one that looked the most promising for my intended use and he seems to have dropped all development of it in favor of qaoed, so i have forked the aoeserver and created a project for it on http://code.google.com/p/aoeserver/
Quite a n00b in device-driver development so it will probably take a while before i get up to speed with this, but keep your eyes open, or maybe help out *wink*, and you might find something there soon. :)
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