individual file system bigger than 1Tbyte anytime soon?

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individual file system bigger than 1Tbyte anytime soon?

Matthias Bertschy
Hello,

I am in the process of creating a server codenamed "terabyte server"  
which will hold some of our backups.
The setup is fairly easy: a RAID card and four 300G ATA drives which  
will make approx 1.2Tbyte.

Of course I chose OpenBSD 3.8 for it. During the installation  
process, I realised my biggest problem: OpenBSD doesn't want to make  
file systems as big as 1.2Tbyte.

In fact, I did my homework and read the FAQ 14.7 which states  
"OpenBSD supports an individual file system of up to 231-1, or  
2,147,483,647 sectors, and as each sector is 512 bytes, that's a tiny  
amount less than 1T."

Ok, well, I am not a system programmer, but would it be difficult to  
make an OpenBSD support for 2Tbyte file systems like on Linux? (for  
the moment "terabyte server" runs Linux, but I would prefer OpenBSD)

Thanks for your help!

Matthias Bertschy

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Re: individual file system bigger than 1Tbyte anytime soon?

Ted Unangst-2
On 11/8/05, Matthias Bertschy <[hidden email]> wrote:
> I am in the process of creating a server codenamed "terabyte server"
> which will hold some of our backups.
> The setup is fairly easy: a RAID card and four 300G ATA drives which
> will make approx 1.2Tbyte.
>
> Of course I chose OpenBSD 3.8 for it. During the installation
> process, I realised my biggest problem: OpenBSD doesn't want to make
> file systems as big as 1.2Tbyte.

is the filesystem you are backing up 1.2TB?

you also want to search recent archives.

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Re: individual file system bigger than 1Tbyte anytime soon?

Nick Holland
In reply to this post by Matthias Bertschy
Matthias Bertschy wrote:
> Hello,
>
> I am in the process of creating a server codenamed "terabyte server"  
> which will hold some of our backups.
> The setup is fairly easy: a RAID card and four 300G ATA drives which  
> will make approx 1.2Tbyte.

actually, by the time you get done with marketing-speak, you are closer
to 1T (OpenBSD's capacity isn't in marketing-speak).  Of completely
non-redundant, 4x failure point, new technology disk space.  Be scared.

(math: the 300G drives I've seen are about 280G.  280Gx4 = 1120G
1120G / 1024G/TB = 1.09TB.  Maybe your "300G" drives are bigger than the
ones I've seen...don't count on it)

> Of course I chose OpenBSD 3.8 for it. During the installation  
> process, I realised my biggest problem: OpenBSD doesn't want to make  
> file systems as big as 1.2Tbyte.
>
> In fact, I did my homework and read the FAQ 14.7 which states  
> "OpenBSD supports an individual file system of up to 231-1, or  
> 2,147,483,647 sectors, and as each sector is 512 bytes, that's a tiny  
> amount less than 1T."
>
> Ok, well, I am not a system programmer, but would it be difficult to  
> make an OpenBSD support for 2Tbyte file systems

VERY difficult.
Think about the consequences of even the smallest error.  Think about
how you test EVERY IMAGINABLE edge case.  Think about how long it takes
to fix things when your test 2TB disk array gets hosed.  Again.
[totally OT: ever think about how much frustration Marco and crew had to
go through to get all that cool bioctl stuff working?  "DANG, that
didn't work, time to reboot the server...AGAIN!"  Rebooting those
servers he was working with is a most unpleasant task...]

Yes, it has to be done, but it will be done when someone does it.  You
don't expect I (or anyone else) can give you a date, do you?  I can
pretty well tell you it won't be in 3.9, as such a beast would probably
have to be committed the day after unlock (long before you get your CDs)
in order to be sufficiently tested for the next release.  I can assure
you, you will know when it happens.

> like on Linux?

oh, thrash from File-system-of-the-week to file-system-of-the-week? that
might not be so difficult. (ok, cheap shot, I know, couldn't resist).

> (for
> the moment "terabyte server" runs Linux, but I would prefer OpenBSD)

A story:
Long ago, when the first 1G drives came out, they were a small hair
bigger than 1G in size.  The way MSDOS handled them, because of that
hair, they went to the largest block size (32k).  Throw away a tiny
amount of space (I think it was something like 10M or less), MSDOS would
slip to a 16k block size, and the user would end up with effectively
considerably more usable space.  However, people would see me
partitioning down their disk and would say, "I PAID FOR IT, I WANT IT
ALL!", or insist that I give them a 10M D: partition.  (Worst case I saw
was a client with a full 200M HD, lots of tiny files.  She got a new
computer, with a "huge" 1G disk, copied her old disk over and she ended
up with...200M of free space, all due to this block size issue).

The point:
Sometimes people obsess over the silliest things, and hurt themselves in
the process.

For 1.1T of disk space, either break it down to two 550M chunks, or just
throw away the 100G. (or use it as a separate "test" partition)  You
won't miss it...at least, until one of those drives fails, and you wish
you threw away an entire 280G and went with redundancy.

"But!  I want it all in one file system!"
Ok, so what do you do when the 1.1TB becomes insufficient?  You are
going to buy four new, bigger drives, and another controller and copy
everything to the new drive and throw away the old ones?  Probably not:
you will probably just add some more storage and make it two file
systems.  Just do that now. :)

Seriously, if you can't manage multiple blocks of data now, odds are you
are going to be in big trouble when that "big" system starts looking
small.  IF you really think you won't outgrow that "big" 1.1TB system
and don't have to worry about add-on storage, you can certainly throw
away 100G and run your prefered OS.

I'm really curious how you are going to back that thing up, too.  4x
failure points and relatively cutting edge disks...it better be GOOD.

Nick.

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Re: individual file system bigger than 1Tbyte anytime soon?

Matthias Bertschy-2
In reply to this post by Ted Unangst-2
 Ted Unangst wrote:

  On 11/8/05, Matthias Bertschy   <[hidden email]>   wrote:

    I am in the process of creating a server codenamed "terabyte server"
    which will hold some of our backups.
    The setup is fairly easy: a RAID card and four 300G ATA drives which
    will make approx 1.2Tbyte.
   
    Of course I chose OpenBSD 3.8 for it. During the installation
    process, I realised my biggest problem: OpenBSD doesn't want to make
    file systems as big as 1.2Tbyte.

  is the filesystem you are backing up 1.2TB?

no, but for convenience we would like to have only one file system on our
backup server

  you also want to search recent archives.

ok, I will look for answers into mailling list's archives
but so far Google didn't help me.

Thanks,

Matthias Bertschy