Date: Wed, 7 Feb 2024 14:52:40 +0100 From: Julien Cigar <julien@perdition.city> To: Andrea Brancatelli <andrea@brancatelli.it> Cc: Ben RUBSON <ben.rubson@gmx.com>, fs@freebsd.org Subject: Re: Re: ZFS on a shared iSCSI Message-ID: <z7ktkxbiqcmxb247rowqgjjqqpwnvu7xw4dmz2ypk7ebmss2ur@dbh55hhd4isr> In-Reply-To: <CAGqQmRMJp8Rs6ZChkrqRm1sDpjKjj%2B2n=hT2nUk1Nsq6pfOQnw@mail.gmail.com> References: <CAGqQmRPssfrb9S6r0H4SaQLEfOTp5Qx7-HSvHtYkxMnpeqKWjQ@mail.gmail.com> <FADEDED8-7C34-4C14-A251-00F4EFBEE6ED@gmx.com> <CAGqQmRMJp8Rs6ZChkrqRm1sDpjKjj%2B2n=hT2nUk1Nsq6pfOQnw@mail.gmail.com>
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--3h47p2q2wl5agv2k Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 07, 2024 at 02:36:18PM +0100, Andrea Brancatelli wrote: > On Wed, Feb 7, 2024 at 12:25=E2=80=AFPM Ben RUBSON <ben.rubson@gmx.com> w= rote: >=20 > > > On 7 Feb 2024, at 11:55, Andrea Brancatelli <andrea@brancatelli.it> > > wrote: > > > > > > Would it be "easily possible" to have some (2?) iSCSI LUN exposed to > > both servers and then activate the pool on one or the other server? > > > > Hi Andrea, > > > > Yes, I have such configurations : > > 2 servers with same JBODs configuration. > > When zpool is mounted on server A, mirroring is done on both local disks > > and iSCSI disks from server B. > > When zpool is mounted on server B, mirroring is done on both local disks > > and iSCSI disks from server A. > > Works flawlessly. > > And you can have one of the 2 servers offline for some time, when it wi= ll > > be back online, sync will restart. > > What you can't have is zpool online on both servers at the same time. > > > > So you can do the same with iSCSI disks only. > > Disks will have to be mounted on one server at a time only. > > > > You'll have to have a rather low network / iSCSI latency, or it will fa= il > > / zpool will be unusable. > > If you have high latency, you'll have to go for ZFS send/receive. > > >=20 > That sounds like an interesting setup, although we have an external iSCSI > "SAN" so the iSCSI approach would be totally offloaded, without any local > storage. >=20 > Imagine Server A having a certain LUN on the iSCSI device and Server B > having another one. >=20 > If a server fails, the idea would be to activate the pool "on the fly" on > the other one. >=20 > Otherwise I totally take iSCSI out of the picture (less is better), have > local disks and zfs-snapshot stuff back and forth. If you can afford to lose x minutes of data then this is the way. FYI we use zrepl here, with snapshots taken every 5 minutes (sent both locally to another bare metal server, an offsite to a remote Hetzner instance over a wireguard link) >=20 >=20 >=20 >=20 >=20 > --=20 > *Andrea Brancatelli* --=20 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. --3h47p2q2wl5agv2k Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEnF27CBNtOraRNmgqCLYqJMpBHmkFAmXDiygACgkQCLYqJMpB HmnWqA//c+1mrGmfxzd9TQ/RsClPGkfH/l/zSnjqOEn1gJEpUslcf6tTYGV69Ewn zHay7ZrDtWZA4xMru9pmZOBpEMMeN14b0i5Pt9WDHxKlC0RwiIuZpdeFvIDbGUQN 5O1EJLUz5ypp7NAaXoJR/bCsMv/cgqgxTnJy18bVTLcp5MmNkdmtAZHM9EVHhLpH HQxYTAQFyozMRkvB8uBkCWcAY3vKv/kkS/ACzXyfX20lbK3rhU2chvQnMob4xz6o Chjp9rClXvLU5LLOT4Sl2qNuRaTaJBqJuCu9Iqo10HBxUraqJFPgZ1lB3KWRb68P R7rykr5BO+9DdRG4VW03u4zsv7MaWilNvGIdii9qXi1RDuxsrdzva9SU0JWTDg9Q noZEwwpGiBGOSlqhkpO1L75Q2jJl45agcyGtRMbOkSLlIvh/3qjNHQGkBQnm5d/N k3fjtgW+A6DgqpkD4ZVJvfR3uEvS+9vH3q9qviIyt1OT2Hg8yFRIuQr6E7YHTiUQ kT5YrIBWXHZmhw5FhWzgvLC1Of1JG6Wbhrg55ALYFQXXfULHcYNe8TsmMtPSEFuw 090T7cs4Pq99SOABgFwAaAFATbo52O1mT2fKWEB9ktTB2jxiT/mJ3hK/rcZx4tvP tr3b0l3YkPHBg67NP9YiZwbaADIeWIMxg3ZKmPvy3Cm6Dh7k2jA= =M148 -----END PGP SIGNATURE----- --3h47p2q2wl5agv2k--
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