[lustre-discuss] free space on ldiskfs vs. zfs

Götz Waschk goetz.waschk at gmail.com
Mon Aug 24 23:40:19 PDT 2015

Dear All,

I'm sorry, I cannot provide verbose zpool information anymore. I was a
bit in a hurry to put the file system into production and that's why I
have reformatted the servers with ldiskfs.

On Tue, Aug 25, 2015 at 5:54 AM, Alexander I Kulyavtsev <aik at fnal.gov> wrote:
> I was assuming the question was about total space as I struggled for some time to understand  why do I have 99 TB total available space per OSS, after installing zfs lustre, while ldiskfs OSTs have 120 TB on the same hardware. The 20% difference was partially (10%) accounted by different raid6 / raidz2 configuration. But I was not able to explain the other 10%.

> For question in original post, I can not make 24 TB from "available" field of df output:
> 207 KiB "available" on his zfs lustre,  198 KiB on ldiskfs lustre.
> At the same time the difference of the total space is
> 233548424256 -207693153280 = 25855270976 KiB = 24.09 TB.

> Götz, could you please tell us what did you mean by "available" ?

I was comparing the Lustre file system size from the two
configurations, the space available for user data. I expected it to be
the same, that is 218T for both file systems.

I understand that you have the same issue.

Regards, Götz Waschk

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