From owner-freebsd-fs@freebsd.org Mon Jan 21 16:00:20 2019 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A1FCC14ADB13 for ; Mon, 21 Jan 2019 16:00:20 +0000 (UTC) (envelope-from gpalmer@freebsd.org) Received: from mail.in-addr.com (mail.in-addr.com [IPv6:2a01:4f8:191:61e8::2525:2525]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 129EA8F752 for ; Mon, 21 Jan 2019 16:00:20 +0000 (UTC) (envelope-from gpalmer@freebsd.org) Received: from gjp by mail.in-addr.com with local (Exim 4.91 (FreeBSD)) (envelope-from ) id 1glbzk-000B2f-Ut; Mon, 21 Jan 2019 16:00:17 +0000 Date: Mon, 21 Jan 2019 16:00:16 +0000 From: Gary Palmer To: Borja Marcos Cc: jdelisle , freebsd-fs Subject: Re: ZFS on Hardware RAID Message-ID: <20190121160016.GC45377@in-addr.com> References: <1180280695.63420.1547910313494.JavaMail.zimbra@gausus.net> <92646202.63422.1547910433715.JavaMail.zimbra@gausus.net> <1691666278.63816.1547976245836.JavaMail.zimbra@gausus.net> <92746659-4B3F-415C-BB6A-6C99837AFAF2@sarenet.es> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <92746659-4B3F-415C-BB6A-6C99837AFAF2@sarenet.es> X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: gpalmer@freebsd.org X-SA-Exim-Scanned: No (on mail.in-addr.com); SAEximRunCond expanded to false X-Rspamd-Queue-Id: 129EA8F752 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.97 / 15.00]; local_wl_from(0.00)[freebsd.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.996,0]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; NEURAL_HAM_SHORT(-0.98)[-0.976,0]; ASN(0.00)[asn:24940, ipnet:2a01:4f8::/29, country:DE] X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 21 Jan 2019 16:00:20 -0000 On Mon, Jan 21, 2019 at 03:17:08PM +0100, Borja Marcos wrote: > > > > On 20 Jan 2019, at 16:33, jdelisle wrote: > > I can say for certain that with Dell PERC 6/e RAID (SAS 8087ELP based) > > cards, when the virtual devices are entire disks each in a RAID0 > > configuration, the way the adapter writes data to them is effectively the > > same as JBOD. You can take a RAID0 drive from a PERC 6/e controller and > > use in with an HBA/ "IT Mode" JBOD controller without issue. I personally > > migrated 14x 1TB drives off PERC 6/e (all RAID0's) to a SAS 6gbps HBA, and > > my ZFS VDEV's and pools were totally fine. You can move back and forth no > > problem. I can't say this is the case for ALL RAID controllers, I've only > > done this with an old PERC 6/e. > > However a single disk RAID0 volume (what manufacturers call a JBOD) is not the same > as a disk. With the ???virtual JBOD??? you lose direct CAM access, which means that some > advanced options won???t be supported. > > For example, if you are using SSDs ZFS knows when to issue a TRIM (or, in general, > BIO_DELETE) command. Does the ???virtual JBOD??? offer that option? > > The same could be said of other functionalities available when you talk directly > to the disks. This is a pertinent point. If I remember right, no LSI RAID controller supports TRIM/UNMAP on SSDs. Spinning rust is OK in a RAID controller, but if you have SSDs attached to the LSI RAID controller and plan to use them in ZFS it is better to get a HBA instead. I don't know about other RAID controller manufacturers. Regards, Gary