Steve Lord wrote:
> > So, xfs_info shows this:
> >
> > [root@sdssdp10 dp]# xfs_info /export/data/dp10.a/
> > meta-data=/export/data/dp10.a isize=512 agcount=268, agsize=1048576
> > blks
> > data = bsize=4096 blocks=280145408, imaxpct=25
> > = sunit=128 swidth=256 blks, unwritten=0
> > naming =version 2 bsize=4096
> > log =internal bsize=4096 blocks=32768
> > realtime =none extsz=1048576 blocks=0, rtextents=0
>
> This is picking up info from the software raid, it does not see any
> info from the hardware. As far as it is concerned, you have two devices
> the stripe unit (amount of data written to one device before it switches
> to the next device) is 128 file system blocks, or 512Kbytes, the stripe
> width (or amount of data before it cycles back to the first device
> again) is twice this (2 devices).
Right, I expect that - the SW RAID0 array is hiding the HW RAID5 array below
it.
> You can override the automatically selected values at mkfs time, the
> tricky part is working out what values will work for you. To quote from
> the man page:
Yeah. I read it. After mkp beat me with a stick it's starting to make
sense:
* mkp grabs his bat and looks for yocum
* yocum runs and looks quizically at mkp.
<mkp> chunk-size == stripe unit
<yocum> ok
<mkp> stripe width == disks * stripe unit
<yocum> ah hah! see, now, if there were an example in the man pages I'd
get it.
I paraphrase, of course... ;-)
> p.s. interested in testing some code to allow you to use 256 byte inodes
> on a device bigger than 1 Tbyte?
Sure - I'll have a machine free for a couple weeks - if you want access to
it, too, let me know.
Cheers,
Dan
--
Dan Yocum
Sloan Digital Sky Survey, Fermilab 630.840.6509
yocum@xxxxxxxx, http://www.sdss.org
SDSS. Mapping the Universe.
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