[lustre-discuss] patchless server vs. patched server

Andreas Dilger adilger at whamcloud.com
Fri Jun 5 06:28:46 PDT 2020

Thanks for taking the time to update the wiki, every contribution helps.

Note that the need for patches kernels for project quotas will also go
away with newer kernels, but Red Hat just couldn't make that feature work
with the RHEL7 kernel without breaking the ABI.

Cheers, Andreas

On Jun 2, 2020, at 06:51, Pascal Suter <pascal.suter at dalco.ch> wrote:

Hi George

that used to be the case until before 2.10.1, but since 2.10.1 even ldiskfs does not require a patch anymore. I have actually updated from a patched 2.10.3 to 2.12.4 patchless and i am using ldiskfs for my MDTs  and ZFS for the OSTs

but i think i just found out why there are still both versions being packed.. while i was looking for a link to quote regarding ldiskfs now working without a patch, i actually found the announcement of 2.10.1  at http://lustre.org/lustre-2-10-1-released/ which states

   "Patchless server build for ldiskfs is now routinely provided. Note that the patched kernel version must still be used to make use of project quotas"

And here is the document that my question was based upon:


it states:

"Note: With the release of Lustre version 2.10.1, it is possible to use patchless kernels for Lustre servers running LDISKFS. The patchless LDISKFS server distribution does not include a Linux kernel. Instead, patchless servers will use the kernel distributed with the operating system."

and here is a LUDOC issue regarding documenting this in the official lustre documentation:


(amazing what you can find once you know what to look for ;))

i have applied for a lustre.org wiki account to add this missing piece of information which should help people to choose better if they want to use the patched or patchless kernel. luckily i'm not using the project quota feature ;)



On 6/2/20 1:50 PM, George Melikov wrote:
IIRC "patchless server" can only serve ZFS based backends.
So, it you really need ldiskfs - you're stuck with patched kernel for now.

27.05.2020, 18:41, "Pascal Suter" <pascal.suter at dalco.ch><mailto:pascal.suter at dalco.ch>:

Hi all

i am currently upgrading a lustre 2.10.3 to 2.12.4 on CentOS 7.7 and I
am unsure if I should use the patchless or patched server version. what
is the advantage of still using the patched server version over using
the patchless variant? From an linux sysadmin point of view I prefer to
use an unpatched kernel and it would seem unnecessary to still maintain
a patched variant if they both worked the same in the end.



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George Melikov

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