[lustre-discuss] What does your (next) MDT look like?

[Dilger, Andreas]

I definitely think this would be interesting.  It needs some testing, and very likely a bit of work to get inline_data to work together with Lustre, but it makes sense now that DoM is available.  With the change to 1KB inode size in ldiskfs MDTs, this should allow files up to about 700 bytes to be stored inside the inode (or larger if the inode size was increased).

Cheers, Andreas

> On Feb 23, 2018, at 07:58, Ben Evans <bevans at cray.com> wrote:
> 
> Slightly left-field question for MDTs, will we enable data on inode for
> really tiny files in ldiskfs?
> 
> -Ben
> 
> On 2/22/18, 2:02 PM, "lustre-discuss on behalf of Dilger, Andreas"
> <lustre-discuss-bounces at lists.lustre.org on behalf of
> andreas.dilger at intel.com> wrote:
> 
>> On Feb 6, 2018, at 10:32, E.S. Rosenberg <esr+lustre at mail.hebrew.edu>
>> wrote:
>>> 
>>> Hello fellow Lustre users :)
>>> 
>>> Since I didn't want to take the "size of MDT, inode count, inode size"
>>> thread too far off-topic I'm starting a new thread.
>>> 
>>> I'm curious how many people are using SSD MDTs?
>>> Also how practical is such a thing in a 2.11.x Data On MDT scenario?
>>> Is using some type of mix between HDD and SSD storage for MDTs
>>> practical?
>>> Does SSD vs HDD have an effect as far as ldiskfs vs zfs?
>> 
>> It is worthwhile to mention that using DoM is going to be a lot easier
>> with ZFS in a "fluid" usage environment than it will be with ldiskfs.
>> The ZFS MDTs do not have pre-allocated inode/data separation, so enabling
>> DoM will just mean you can put fewer inodes on the MDT if you put more
>> data there.  With ldiskfs you have to decide this ratio at format time.
>> The drawback is that ZFS is somewhat slower for metadata than ldiskfs,
>> though it has improved in 2.10 significantly.
>> 
>> Cheers, Andreas
>> --
>> Andreas Dilger
>> Lustre Principal Architect
>> Intel Corporation
>> 
>> 
>> 
>> 
>> 
>> 
>> 
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> 

Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Intel Corporation