Date: Sat, 19 Feb 2005 18:40:48 -0600 From: Eric Anderson <anderson@centtech.com> To: ticso@cicely.de Cc: Matthew Jacob <lydianconcepts@gmail.com> Subject: Re: newfs limits? 10TB filesystem max? Message-ID: <4217DC90.5090202@centtech.com> In-Reply-To: <20050220000418.GU14312@cicely12.cicely.de> References: <20050216224825.39102.qmail@web26807.mail.ukl.yahoo.com> <4213D046.4080001@centtech.com> <7579f7fb05021715344d661662@mail.gmail.com> <421605D0.80302@centtech.com> <20050218172831.GA9944@freebie.xs4all.nl> <4217BAC5.10504@centtech.com> <20050220000418.GU14312@cicely12.cicely.de>
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Bernd Walter wrote:
> On Sat, Feb 19, 2005 at 04:16:37PM -0600, Eric Anderson wrote:
>
>>Wilko Bulte wrote:
>>
>>>On Fri, Feb 18, 2005 at 09:12:16AM -0600, Eric Anderson wrote..
>>>
>>>
>>>>Matthew Jacob wrote:
>>>>
>>>>
>>>>>BTW- be careful with very large filesystems on FreeBSD- at some point
>>>>>fsck can't check them.
>>>>>
>>>>>I built a sparse 5000TB filesystem which newfs'd and mounted okay, but
>>>>>was not possible to check with fsck.
>>>>
>>>>5000TB?!?! How did you do that?
>>>
>>>
>>>Note the word 'sparse' :)
>>
>>
>>That doesn't explain it much.. Is there a doc on how to create these sparse
>>filesystems?
>
>
> Creating sparse files, e.g. by using dd, is prety much unix basics.
> And via md(4) you can get a disk type device from a file.
Sorry - I understand how to make a file with dd, but 5000TB filesystem means to me someone has 5PB of space to put the filesystem on.. I had not heard anyone call a file a 'sparse file' with regards to dd before this, and the man page info for dd and sparse isn't all that telling.
> testdisk=/tmp/testdisk
> dd if=/dev/zero bs=512 count=1 oseek=2m of=${testdisk}
> mdev=`mdconfig -a -t vnode -f ${testdisk}`
>
> I don't know if md(4) works with such large disks, but it's very likely
> that is does.
I see that running the command gives a 1GB file, that takes very little disk space. I must have missed this option in the dd man pages, or never looked for it.
Thanks for the command line
Eric
--
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Eric Anderson Sr. Systems Administrator Centaur Technology
I have seen the future and it is just like the present, only longer.
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