From nobody Wed Feb 7 13:36:18 2024 X-Original-To: fs@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4TVLk8284hz59P9P for ; Wed, 7 Feb 2024 13:36:32 +0000 (UTC) (envelope-from andrea@brancatelli.it) Received: from mail-lf1-x12f.google.com (mail-lf1-x12f.google.com [IPv6:2a00:1450:4864:20::12f]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1D4" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4TVLk75Dclz43sr for ; Wed, 7 Feb 2024 13:36:31 +0000 (UTC) (envelope-from andrea@brancatelli.it) Authentication-Results: mx1.freebsd.org; none Received: by mail-lf1-x12f.google.com with SMTP id 2adb3069b0e04-5116588189aso1080715e87.1 for ; Wed, 07 Feb 2024 05:36:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brancatelli-it.20230601.gappssmtp.com; s=20230601; t=1707312990; x=1707917790; darn=freebsd.org; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=2ePsxSa/pYAJsd5P/NU0v+6bps8wWGq9Cw+0VNFFOb8=; b=JB2M4T2MOhsPNr5HsDFXyRrOymApWRiCdQDqu9sXST56GsYG6oUZttz43kncG5UnsL Vi0ZbqkIvltH7+zRBFRg+3J6GPD6jvcDwLVv+RfZOK/UAmqaXcsA1c03QyrOauGFPNqI Ii9XKCKKD+oWbtFaZe8d57SiKTkQsQt1fpDVWzu+05AX3PXjPnjOARAiZ9dN5QEFC3LJ 6RWmeknCTIZqKxH6nO1/X6QM8ecfc9gbg0e1QXl2tIBOlBMz9HjRkSeizIZFbr8U6xAX CljnewO2HfM3LbxMyeRUoJjZGsi8kSpeO/DXHZTfHPwK+PJKXvAIAlVobDfP1XBwhmE4 CNFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707312990; x=1707917790; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=2ePsxSa/pYAJsd5P/NU0v+6bps8wWGq9Cw+0VNFFOb8=; b=dF3GPKUknpQdOwpMPOdD5y/N9VZ9vSX/rM8yVVaz7+Wxqjf5ChDJDf+ilGB5AD4Qvm OPR07M7VMjKv8IXASe3mjiLEjvyNh/JJju6AfJjEZ5JerkU2UgVTp+Hi7yA21duj+weq oeAlvziJ29HoAg+htDS48Lwq7knWU8bVNyeogNI6nydTJ+nn3Axb0te6EVGm0zntMCWu YyKtFFGnqRQNgpDq6pyViJ9AigdHX93391G21NFsBbARPFRbsRakddVrVPUHXYKmUbJh WUj9EoU/iMbZ0k93nOk16rdl+zJb1QLaxsCztS3YD23B2OXcDmLa3VzASmfoSSR4Jh85 onwg== X-Gm-Message-State: AOJu0YxfxYEp8Lben6foyN9cIoXyzDN3ra72PhQZ938xzBNGyTeyZE1J fDwlr2aZjSHZPaxT9+iBL3YLKvAfy/89UfneKJB+LaNk1xH67XRn/jmZRCH/5/9yjw5zinYH87/ fq1X+FNT9HhWvD3hjjNZX/ouulaatN/mwDAB6YtdCv+zUpfcU X-Google-Smtp-Source: AGHT+IGv7Q5VPBfJYoMnqISjIwK0mOY9qCDRg3OxTM+voHsh2uBrOoKsp6BK51/j40bOlxouLAeuy0HdRZZnSmiGG9Q= X-Received: by 2002:ac2:593a:0:b0:511:4edb:5acb with SMTP id v26-20020ac2593a000000b005114edb5acbmr3893791lfi.64.1707312989760; Wed, 07 Feb 2024 05:36:29 -0800 (PST) List-Id: Filesystems List-Archive: https://lists.freebsd.org/archives/freebsd-fs List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-fs@freebsd.org MIME-Version: 1.0 References: In-Reply-To: From: Andrea Brancatelli Date: Wed, 7 Feb 2024 14:36:18 +0100 Message-ID: Subject: Re: ZFS on a shared iSCSI To: Ben RUBSON Cc: fs@freebsd.org Content-Type: multipart/alternative; boundary="0000000000004681040610cac869" X-Rspamd-Queue-Id: 4TVLk75Dclz43sr X-Spamd-Bar: ---- X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US] --0000000000004681040610cac869 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, Feb 7, 2024 at 12:25=E2=80=AFPM Ben RUBSON wro= te: > > On 7 Feb 2024, at 11:55, Andrea Brancatelli > 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 will > 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 fail > / zpool will be unusable. > If you have high latency, you'll have to go for ZFS send/receive. > 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. Imagine Server A having a certain LUN on the iSCSI device and Server B having another one. If a server fails, the idea would be to activate the pool "on the fly" on the other one. Otherwise I totally take iSCSI out of the picture (less is better), have local disks and zfs-snapshot stuff back and forth. --=20 *Andrea Brancatelli* --0000000000004681040610cac869 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

On Wed, Feb 7, 2024 at 12:25=E2=80=AFPM B= en RUBSON <ben.r= ubson@gmx.com> wrote:
> On 7 Feb 2024, = at 11:55, Andrea Brancatelli <andrea@brancatelli.it> wrote:
>
> Would it be "easily possible" to have some (2?) iSCSI LUN ex= posed 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 an= d iSCSI disks from server B.
When zpool is mounted on server B, mirroring is done on both local disks an= d iSCSI disks from server A.
Works flawlessly.
And you can have one of the 2 servers offline for some time, when it will b= e 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.

That sounds like an interesting setup, altho= ugh=C2=A0we have an external iSCSI "SAN" so the iSCSI approach wo= uld be totally offloaded, without any local storage.

Imagine Server A having a certain LUN on the iSCSI device and Server B h= aving another one.

If a server fails, the idea wou= ld be to activate the=C2=A0pool "on the fly" on the other one.

Otherwise I totally take iSCSI out of the picture (l= ess is better), have local disks and zfs-snapshot stuff back and forth.


=C2=A0


--
Andrea Brancatelli

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