From: Phillip Susi <psusi@ubuntu.com>
To: Hugo Mills <hugo@carfax.org.uk>,
Hans Stimer <hans.stimer@gmail.com>,
linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: Packed small files
Date: Fri, 10 Feb 2012 14:02:26 -0500 [thread overview]
Message-ID: <4F3569C2.7090809@ubuntu.com> (raw)
In-Reply-To: <20120131164610.GE5531@carfax.org.uk>
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On 1/31/2012 11:46 AM, Hugo Mills wrote:
> So you're looking at a minimum of 413 bytes of metadata overhead
> for an inline file, plus the length of the filename.
>
> Also note that the file is stored in the metadata, so by default
> it's stored with DUP or RAID-1 replication (even if data is set to
> be "single"). This means that you'll actually use up twice this
> amount of space on the disks, unless you create the FS with
> metadata set to "single".
>
> I don't know how these figures compare with other filesystems. My
> entirely uneducated guess is that they're probably comparable,
> with the exception of the DUP effect.
On ext4 you are looking at 256 bytes for the inode, name length + a
few bytes for the directory entry, another few bytes for the hashed
directory entry, and a whole 4k block to hold the data, so ~4300 bytes
( + name length ) of overhead to store a 64 byte file.
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prev parent reply other threads:[~2012-02-10 19:02 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-31 16:21 Packed small files Hans Stimer
2012-01-31 16:46 ` Hugo Mills
2012-02-10 19:02 ` Phillip Susi [this message]
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