Date: Mon, 17 Dec 2012 15:06:55 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: iSCSI vs. SMB with ZFS. Message-ID: <kan8tu$f76$1@ger.gmane.org> In-Reply-To: <CACpH0Md5H2C0a4Cc8iwFa5M6v3oGFXmydbvHPs_MOY53CXiYfA@mail.gmail.com> References: <CACpH0Md5H2C0a4Cc8iwFa5M6v3oGFXmydbvHPs_MOY53CXiYfA@mail.gmail.com>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig62AD3874C4FF67C726A81368 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 12/12/2012 17:57, Zaphod Beeblebrox wrote: > The performance of the iSCSI disk is > about the same as the local disk for some operations --- faster for > some, slower for others. The workstation has 12G of memory and it's > my perception that iSCSI is heavily cached and that this enhances it's > performance. The second launch of a game ... or the second switch > into an area (ie: loading a specific piece of geometry again) is very > fast. > The performance on the SMB share is abysmal compared to the > performance on the iSCSI share. At the very least, there seems to be > little benifit to launching the same application twice --- which is > most likely windows fault. Think about what you have there: With iSCSI you have a block device, which is seen on your workstation as a disk drive, on which it creates a "local" file system (NTFS), and does *everything* like it is using a local disk drive. This includes caching, access permission calculations, file locking, etc. With a network file system (either SMB or NFS, it doesn't matter), you need to ask the server for *each* of the following situations: * to ask the server if a file has been changed so the client can use cached data (if the protocol supports it) * to ask the server if a file (or a portion of a file) has been locked by another client This basically means that for almost every single IO, you need to ask the server for something, which involves network traffic and round-trip delays. (there are smarter network protocols, and even extensions to SMB and NFS, but they are not widely used) --------------enig62AD3874C4FF67C726A81368 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAlDPJwAACgkQ/QjVBj3/HSwYPwCfQDo/0dNhAEO80b1FxsXf6ymb D80Ani4IzL/emewWeNCFV0u4etX2G8G0 =K/Pd -----END PGP SIGNATURE----- --------------enig62AD3874C4FF67C726A81368--
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