Re: mkfs.xfs, lvm, multi-terrabyte hardware array and luks

Eric thanks for the help.  It seems that you are likely correct in regard to the LUKS 2gb threshold.  I am in the process of urandoming (via dd) a large [20gb] LUKS based ext3 partition to see if the writes fail while less than 20gb... I haven't gotten the results yet... because it takes forever.  If this fails to fill the 20gb ext3 with random data then it would be fair to conclude that LUKS has a problem with large partitions [and ext3 has a problem verifying the underlying partition size], right?

In the meantime I have executed a few trial and error tests (by creating various sized lv/LUKS partitions and then mkfs.xfs on them); the results overwhelming suggest that there is a 2gb xfs limitation on LUKS partitions (probably more politically correct to say it the other way around).  Besides relying on LUKS forums are there any other resources that you know of that/who would/could provide a quick solution?

Is there anyway that lvm2 could be contributing to this problem?  Are there any mkfs.xfs commands that I must issue in this [lvm2/LUKS/Large hardware raid6 array] environment?  Are there certain properties that must remain congruent in regard to the raid array, the lvm2 environment, LUKS and/or XFS?

Again, thanks for your time and help.



Thank you for the quick response.  I have posted on a few luks forums to try to delve into this issue a little deeper; if they are aware of a resolution I'll make sure to post it.  The interesting thing is that when I mkfs.ext3 on luks partitions above 2-3gb all is fine; I wish xfs and luks would play nice.....

Eric Sandeen-3 wrote:

pgf111000 wrote:
> When I try to format partitions above 2-3gb my opteron experiences heavy io
> wait; the mkfs.xfs fails, and I receive the following....
>
>  "mkfs.xfs: libxfs_device_zero write failed: Input/output error"
>
> When I format partions below 2-3gb, there is no problem whatsoever.  I can
> mkfs.xfs on a +2-3GB non-luks formated partition without a problem... any
> thoughts?

Sounds like a LUKS problem, maybe it can't do those large offsets?  xfs
certainly can...

I bet you'll find that the 2GB size is the threshold... xfs is just
trying a write():

        if ((bytes = write(fd, z, bytes)) < 0) {
                fprintf(stderr, _("%s: %s write failed: %s\n"),
                        progname, __FUNCTION__, strerror(errno));

maybe try a simple dd write at the end of your large luks device, see
how that goes.

-Eric