Date: Mon, 4 Jul 2016 20:36:43 +0200 From: Julien Cigar <julien@perdition.city> To: Jordan Hubbard <jkh@ixsystems.com> Cc: Ben RUBSON <ben.rubson@gmail.com>, freebsd-fs@freebsd.org Subject: Re: HAST + ZFS + NFS + CARP Message-ID: <20160704183643.GI41276@mordor.lan> In-Reply-To: <61283600-A41A-4A8A-92F9-7FAFF54DD175@ixsystems.com> References: <20160630153747.GB5695@mordor.lan> <63C07474-BDD5-42AA-BF4A-85A0E04D3CC2@gmail.com> <678321AB-A9F7-4890-A8C7-E20DFDC69137@gmail.com> <20160630185701.GD5695@mordor.lan> <6035AB85-8E62-4F0A-9FA8-125B31A7A387@gmail.com> <20160703192945.GE41276@mordor.lan> <20160703214723.GF41276@mordor.lan> <65906F84-CFFC-40E9-8236-56AFB6BE2DE1@ixsystems.com> <B48FB28E-30FA-477F-810E-DF4F575F5063@gmail.com> <61283600-A41A-4A8A-92F9-7FAFF54DD175@ixsystems.com>
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[-- Attachment #1 --] On Mon, Jul 04, 2016 at 10:55:40AM -0700, Jordan Hubbard wrote: > > > On Jul 3, 2016, at 11:05 PM, Ben RUBSON <ben.rubson@gmail.com> wrote: > > > > Of course Jordan, in this topic, we (well at least me :) make the following assumption : > > one iSCSI target/disk = one real physical disk (a SAS disk, a SSD disk...), from a server having its own JBOD, no RAID adapter or whatever, just what ZFS likes ! > > I certainly wouldn’t make that assumption. Once you allow iSCSI to be the back-end in any solution, end-users will avail themselves of the flexibility to also export arbitrary or synthetic devices (like zvols / RAID devices) as “disks”. You can’t stop them from doing so, so you might as well incorporate that scenario into your design. Even if you could somehow enforce the 1:1 mapping of LUN to disk, iSCSI itself is still going to impose a serialization / performance / reporting (iSCSI LUNs don’t report SMART status) penalty that removes a lot of the advantages of having direct physical access to the media, so one might also ask what you’re gaining by imposing those restrictions. I think the discussion evolved a bit since I started this thread, the original purpose was to build a low-cost redundant storage for a small infrastructure, no more no less. The context is the following: I work in a small company, partially financed by public funds, we started small, evolved a bit to a point that some redundancy is required for $services. Unfortunately I'm alone to take care of the infrastructure (and it's only 50% of my time) and we don't have that much money :( That's why I was just thinking of two machines with a simple HBA card, 2x4To, a zpool mirror on those 4 disks (2 local, 2 iSCSI exported), a NFS share on top, and an easy failover procedure.. I understand that iSCSI hides some details, but as far as I know it's the "lowest" level that you can provide to ZFS when the disks are not local, no ? Anyway, thanks for your feedback, it's greatly appreciated! :) Julien > > - Jordan > > _______________________________________________ > freebsd-fs@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" -- Julien Cigar Belgian Biodiversity Platform (http://www.biodiversity.be) PGP fingerprint: EEF9 F697 4B68 D275 7B11 6A25 B2BB 3710 A204 23C0 No trees were killed in the creation of this message. However, many electrons were terribly inconvenienced. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCgAGBQJXeqy3AAoJELK7NxCiBCPAu6MP/Rp6+bsCOYMeyXeMTEdRaR9/ s+LGJSFv1Oh9wsOBY5NwDb7Zf5uSsGOvWig3JkGKk0OdqXwawmziyoJ7LUDRVy73 NKeb+VfZ0cCcPPCMQhsw1ReQHuaBvUO3ZOZfVfj5BCdPwGbXvcJILKsnNH0vW6vV 7PsyZ8O43ieHvJeFhTPw/0Tq+1xrgNhsWpEY1Tb53ChlVHK++ua3Gqwr9SQjM6Lz fyTM0sh2v/kxeS5Zat3aZnqsWhaEohtHzstYi7oeun9p0/A4pWkfvHfWq+DkcS9A 9Uc7H9fXy0FeJexNetFVHXWgeZtlZFO9V94kbolpn6Op7ojY0wyZvt/LOnRRNH9C 2tk2ep9/5oiEORciEcVB0mHlOcveiXV0G1d8yE3oEHkXeQhUJR9F0R0EEvbtoT3E Pl8MI22BiD8c1kEeS4NtY2vYymc4+ZgKZXx5CeZ10mfKuFAf5y6YtdnMNnP5xvft 4iLJg7xuJFEduOAutbfqE8nuV+6uY1jnHVLO8I4wbkm67JI0H86xXO2j58AEqIvE 5hX2vnhOlwhpVg4zzw5R1bEODBFpdQbCAMqasVO/0l0FCfbHw9REFaUF5LoXK3Df OuSXlzlzZRWS7KT3U1mgt65EnN5LxWElLeEI+sBm23wodoD9Up84LpU+5yjWPZ9q AYvFA5gj1nLF05HRsVMW =0oAt -----END PGP SIGNATURE-----
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