From owner-freebsd-fs@freebsd.org Sat Jan 19 20:15:17 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 BFBE414931BE for ; Sat, 19 Jan 2019 20:15:17 +0000 (UTC) (envelope-from ira@wakeful.net) Received: from mail-io1-xd2e.google.com (mail-io1-xd2e.google.com [IPv6:2607:f8b0:4864:20::d2e]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id AC1686CB54 for ; Sat, 19 Jan 2019 20:15:16 +0000 (UTC) (envelope-from ira@wakeful.net) Received: by mail-io1-xd2e.google.com with SMTP id c2so13542964iom.12 for ; Sat, 19 Jan 2019 12:15:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wakeful-net.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=LkWo9cbvk5ar+SjQv7yr9itfx+u+GhEukrmbOzQeZPk=; b=iDiWNi0cJ4wXo4S5pwhUjIH40BwPWZWcVcCPOs/jq27aIK52Tvn5UsKyMtV+2p1/zw 2ogxgtrkBZPJkQnQsjsRg9M9I5dnIyLjfZp+eaAzsSVPQ7ePfxFahs5DIS2M1X7AmszN QCLZnvMBxNB5uNxmeOPnc33OSyVW8pjB1a8lE8zoMYJBJ4RPbuGA5ayO7t5SRWkrC1RF fo2CvoFyTshIcU/ITdEvLO8vB1asI5yoLIpGFRq69z7YdxHxWIWIutwR1Rd6BOL6ikEK 0y9wQxQI0Uq9LfnGMOSgtK5ZVaV/RpBFNZeZwfwQI7xevYlgf90GmxZng0hQ8WeWg48I pKNg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=LkWo9cbvk5ar+SjQv7yr9itfx+u+GhEukrmbOzQeZPk=; b=aD40xnTNyriDmR2/7/EV45ZGYOzRch5StQr6k5R4Wku1BVRlityWO8JW8BKsdjfiyn S8ClhGaifT0m7S+sBaEDywOXDMBnzX5WQaMeUs8z66kQrxbbn1UCNTSeThRZE+I2jEb/ kPoyGJAM3p9XEQJbeXtuME/JbA7bvSLtj4Y/0Z3V/9FUSJSyZqfYNSeB5KPKU5eq81Nk Fuv7NNZDZ5tHYnM+v0sjguSbnSLbSgPRmgD+PFHM1f96ftsaJ5jfX9alCghHBy/+ANr7 EkvU9uEBNNwc6FuRZ8+I93+gVidMGOIuD0MG7fmU5+gX74hVuYJQ8PMDzmg1aUSkHbql eH9w== X-Gm-Message-State: AJcUukeVr8Tmr4Ta3wzRs3vfDQoKBtq20uq8BUfR13xugMm5AKmiYfKp Y4vDRIWZSKAlNjwIfNnOvzJF26LmjcTlAAtP2agkFg== X-Google-Smtp-Source: ALg8bN54kLyv1o7DZ+BKxxn6eSEQB+gMwIaPHPExuHVIo0S3T+/BcxXLLfBwtt0iu5E+2k+GI9vg56Lbw1O12267pA0= X-Received: by 2002:a6b:e00e:: with SMTP id z14mr12366748iog.264.1547928915881; Sat, 19 Jan 2019 12:15:15 -0800 (PST) MIME-Version: 1.0 References: <1180280695.63420.1547910313494.JavaMail.zimbra@gausus.net> <92646202.63422.1547910433715.JavaMail.zimbra@gausus.net> In-Reply-To: From: Ira Cooper Date: Sat, 19 Jan 2019 15:15:05 -0500 Message-ID: Subject: Re: ZFS on Hardware RAID To: Rich Cc: Maciej Jan Broniarz , freebsd-fs X-Rspamd-Queue-Id: AC1686CB54 X-Spamd-Bar: ----- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=wakeful-net.20150623.gappssmtp.com header.s=20150623 header.b=iDiWNi0c X-Spamd-Result: default: False [-5.56 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[wakeful-net.20150623.gappssmtp.com:s=20150623]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-fs@freebsd.org]; DMARC_NA(0.00)[wakeful.net]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[wakeful-net.20150623.gappssmtp.com:+]; MX_GOOD(-0.01)[cached: ASPMX.L.GOOGLE.COM]; RCVD_IN_DNSWL_NONE(0.00)[e.2.d.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.b.8.f.7.0.6.2.list.dnswl.org : 127.0.5.0]; NEURAL_HAM_SHORT(-0.90)[-0.904,0]; R_SPF_NA(0.00)[]; FREEMAIL_TO(0.00)[gmail.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+,1:+]; RCVD_TLS_LAST(0.00)[]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; RCVD_COUNT_TWO(0.00)[2]; IP_SCORE(-2.34)[ip: (-7.43), ipnet: 2607:f8b0::/32(-2.37), asn: 15169(-1.83), country: US(-0.08)] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 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: Sat, 19 Jan 2019 20:15:18 -0000 Well put. In addition, by using a raid controller, you are likely depriving the OS and ZFS the ability to use the drive's writeback caches, and queue depth management. Cheers, -Ira On Sat, Jan 19, 2019 at 3:09 PM Rich wrote: > The two caveats I'd offer are: > - RAID controllers add an opaque complexity layer if you have problems > - e.g. if you're using single-disk RAID0s to make a RAID controller > pretend to be an HBA, if the disk starts misbehaving, you have an > additional layer of behavior (how the RAID controller interprets > drives misbehaving and shows that to the OS) to figure out whether the > drive is bad, the connection is loose, the controller is bad, ... > - abstracting the redundancy away from ZFS means that ZFS can't > recover if it knows there's a problem but the underlying RAID > controller doesn't - that is, say you made a RAID-6, and ZFS sees some > block fail checksum. There's not a way to say "hey that block was > wrong, try that read again with different disks" to the controller, so > you're just sad at data loss on your nominally "redundant" array. > > - Rich > > On Sat, Jan 19, 2019 at 11:44 AM Maciej Jan Broniarz > wrote: > > > > Hi, > > > > I want to use ZFS on a hardware-raid array. I have no option of making > it JBOD. I know it is best to use ZFS on JBOD, but > > that possible in that particular case. My question is - how bad of an > idea is it. I have read very different opinions on that subject, but none > of them seems conclusive. > > > > Any comments and especially case studies are most welcome. > > All best, > > mjb > > _______________________________________________ > > 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" > _______________________________________________ > 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" >