Date: Fri, 15 Sep 2000 11:26:18 +0930 From: Greg Lehey <grog@lemis.com> To: Dan Nelson <dnelson@emsphone.com> Cc: Bruce Petro <bpetro@usa.com>, freebsd-questions <freebsd-questions@FreeBSD.ORG> Subject: Re: Compare FBSD File System Message-ID: <20000915112618.L71517@wantadilla.lemis.com> In-Reply-To: <20000914140402.A5897@dan.emsphone.com>; from dnelson@emsphone.com on Thu, Sep 14, 2000 at 02:04:02PM -0500 References: <380327008.968949972194.JavaMail.root@web302-mc.mail.com> <20000914140402.A5897@dan.emsphone.com>
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On Thursday, 14 September 2000 at 14:04:02 -0500, Dan Nelson wrote:
> In the last episode (Sep 14), Bruce Petro said:
>> Could someone shoot back a brief review of how the FBSD file system
>> compares to the old FAT system? General information is fine, but
>> please also cover:
>>
>> 1. Efficient Disk Usage - any min file size etc like fat?
>
> ffs has an 8k blocksize and a 1k fragment size. Small files and the
> ends of large files are put into fragments.
You have a choice of block and frag size. Basically,
1. Frags must be a power of 2 and at least 512 bytes long.
2. Blocks may contain 1 (I think), 2, 4 or 8 frags.
3. Theoretically blocks may be any size within the above constraints,
but in practice you'd probably run into problems with blocks of
more than 64 kB.
4. The larger the block size, the fewer inodes newfs reserves (though
you can override this choice).
In practice, you'd normally use either 4kB/512B for small files, or 8
kB/1kB for larger files.
>> 3. Any disk size limits? I believe I've seen some say there are
>> limits in the size disk you can use, but others seemed to reply
>> and say that that was old limits.
>
> There are always limits; I think the filesystem code has a 1TB
> filesystem-size limit, and you should be able to put a single 1TB
> file in that filesystem without any problems.
I think the maximum file and file system sizes depend on the block
sizes. I think the 1 TB limit is for 8kB/1kB file systems.
Greg
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