2002-09-18 20:05:53

by H. J. Lu

[permalink] [raw]
Subject: PATCH: Support tera byte disk

For a 1.8TB SCSI HD, kernel reports:

SCSI device sda: -773086208 512-byte hdwr sectors (-395819 MB)

Here is a patch to fix it. BTW, I don't think it will work with > 2TB,
which requires bigger changes.


H.J.


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2002-09-18 20:29:41

by Andreas Dilger

[permalink] [raw]
Subject: Re: PATCH: Support tera byte disk

On Sep 18, 2002 13:11 -0700, H. J. Lu wrote:
> For a 1.8TB SCSI HD, kernel reports:
>
> SCSI device sda: -773086208 512-byte hdwr sectors (-395819 MB)
>
> Here is a patch to fix it. BTW, I don't think it will work with > 2TB,
> which requires bigger changes.

There's also a limit where statfs() overflows at 16TB for 4kB block
filesystems... Ask me how I noticed this ;-)

Luckily, it is easy to upshift f_blksz and downshift f_blocks, f_bfree,
and f_bavail to get the data through the statfs interface, and df does
the reverse on the other side. It makes sense to show a larger block
size anyways, so apps potentially do larger I/O requests.

Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/

2002-09-18 22:18:55

by Bryan O'Sullivan

[permalink] [raw]
Subject: Re: PATCH: Support tera byte disk

On Wed, 2002-09-18 at 13:32, Andreas Dilger wrote:

> There's also a limit where statfs() overflows at 16TB for 4kB block
> filesystems... Ask me how I noticed this ;-)

Well, the whole world goes pear-shaped on ia32 with >16TB filesystems,
so statfs is the least of your worries in that case :-(

<b

2002-09-18 22:38:34

by Andreas Dilger

[permalink] [raw]
Subject: Re: PATCH: Support tera byte disk

On Sep 18, 2002 15:23 -0700, Bryan O'Sullivan wrote:
> On Wed, 2002-09-18 at 13:32, Andreas Dilger wrote:
>
> > There's also a limit where statfs() overflows at 16TB for 4kB block
> > filesystems... Ask me how I noticed this ;-)
>
> Well, the whole world goes pear-shaped on ia32 with >16TB filesystems,
> so statfs is the least of your worries in that case :-(

Why do you say that? I've been testing with 60TB or larger filesystems
all week ;-). Note that we can use more than a single block device
and/or remote storage target to store data, so block device limits are
not applicable to us, although 16TB files are a limit we will hit soon.

Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/

2002-09-19 10:28:54

by Mike Black

[permalink] [raw]
Subject: Re: PATCH: Support tera byte disk

Ummm...could you edumacate us on how one constructs a 60TB file system on IA32???
I thought 2TB was the limit.
I'm particularly interested if this is RAID too (I'm a RAID5 fan).
I'm trying to avoid NAS for my next file system upgrade.

----- Original Message -----
From: "Andreas Dilger" <[email protected]>
To: "Bryan O'Sullivan" <[email protected]>
Cc: "H. J. Lu" <[email protected]>; "linux kernel" <[email protected]>
Sent: Wednesday, September 18, 2002 6:41 PM
Subject: Re: PATCH: Support tera byte disk


> On Sep 18, 2002 15:23 -0700, Bryan O'Sullivan wrote:
> > On Wed, 2002-09-18 at 13:32, Andreas Dilger wrote:
> >
> > > There's also a limit where statfs() overflows at 16TB for 4kB block
> > > filesystems... Ask me how I noticed this ;-)
> >
> > Well, the whole world goes pear-shaped on ia32 with >16TB filesystems,
> > so statfs is the least of your worries in that case :-(
>
> Why do you say that? I've been testing with 60TB or larger filesystems
> all week ;-). Note that we can use more than a single block device
> and/or remote storage target to store data, so block device limits are
> not applicable to us, although 16TB files are a limit we will hit soon.
>
> Cheers, Andreas
> --
> Andreas Dilger
> http://www-mddsp.enel.ucalgary.ca/People/adilger/
> http://sourceforge.net/projects/ext2resize/
>
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