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[5.90.149.163]) by smtp.gmail.com with ESMTPSA id k8-20020a5d5248000000b00313f9a0c521sm11035799wrc.107.2023.07.10.01.22.56 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 10 Jul 2023 01:22:56 -0700 (PDT) In-Reply-To: References: X-Referenced-Uid: 73051 Thread-Topic: [linux-lvm] Documentation about allowing >2 disk failures? X-Is-Generated-Message-Id: true X-Blue-Identity: !l=251&o=43&fo=1625&pl=138&po=0&qs=PREFIX&f=HTML&n=Roberto%20Fastec&e=roberto.fastec%40gmail.com&m=!%3ANjc1YWQ4YzEtOTRkNS00ZmZmLWE0YjEtYTEzYWRhYTNmYmVi%3ASU5CT1g%3D%3ANzMwNTE%3D%3AANSWERED&p=105&q=SHOW User-Agent: Android MIME-Version: 1.0 X-Local-Message-Id: <0d6ce898-371d-4dba-b07e-09ca5a101752@gmail.com> From: Roberto Fastec Date: Mon, 10 Jul 2023 10:22:56 +0200 To: LVM general discussion and development Message-ID: <0d6ce898-371d-4dba-b07e-09ca5a101752@gmail.com> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Mailman-Approved-At: Tue, 11 Jul 2023 06:32:29 +0000 Subject: Re: [linux-lvm] Documentation about allowing >2 disk failures? X-BeenThere: linux-lvm@redhat.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: LVM general discussion and development Errors-To: linux-lvm-bounces@redhat.com Sender: "linux-lvm" X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: gmail.com Content-Type: multipart/mixed; boundary="===============3588157545266290745==" --===============3588157545266290745== Content-Type: multipart/alternative; boundary="----Y9FYIY5QCBN53AQX6ETASQVLJCFK6Q" ------Y9FYIY5QCBN53AQX6ETASQVLJCFK6Q Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Hello Tim LVM is a sort of layer and it can reside on any substrate So go for raid 60 and avoid using too many drives for each RAID 6=20 Ideally I would use maximum=C2=A0 6x drives for each RAID 6 to next be stac= k on RAID 10 with the others bear in=C2=A0 mind that there is a calculation about guaranteed failure of = given RAID rebuild process when you exceed a certain amount of terabytes ca= pacity to rebuild That is why enterprise storages with lot of terabytes are always subdivided= in the needed amount of RAID 5 or RAID 6 blocks to be next stack on RAID 5= 0 or RAID 60 At recuperodatiraidfastec.it we have seen so many cases of failed rebuilds = due to leak of calculation before implementation Kind regards Roberto Gini CTO @ https://www RecuperoDatiRAIDFAsTec.it =E2=81=A3Ottieni BlueMail per Android =E2=80=8B Il giorno 10 lug 2023, 08:47, alle ore 08:47, Tim 'mithro' Ansell ha scritto: >Hello! > >RAID5 survives 1 disk failure and RAID6 survives 2 disk failures. What >about going beyond 2 disk failures? Does anyone know where I can find >information on what good options might be? > >I was looking at RAID10, but every extra mirror added only increases >failure tolerance by 1 disk. I am also not seeing any inbuilt support >in >LVM for RAID50 or RAID60 but it seems like if I manually build the >sub-volumes, things should still be fine? > >My system has 25 disks and I'd like to tolerate up to ~1/3rd of the >disks >failing so I was thinking that a RAID1 with 3 mirrors built out of >RAID6 >with 8 disks each (and 1 hot spare) would be a potentially good option? > >Thank you for your help! > >Tim 'mithro' Ansell > > >------------------------------------------------------------------------ > >_______________________________________________ >linux-lvm mailing list >linux-lvm@redhat.com >https://listman.redhat.com/mailman/listinfo/linux-lvm >read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ ------Y9FYIY5QCBN53AQX6ETASQVLJCFK6Q Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Hello Tim
LVM is a sort of layer and it can reside on any substrate=

So go for raid 60 and avoid using too many drives for eac= h RAID 6
Ideally I would use maximum=C2=A0 6x drives for each RAID= 6 to next be stack on RAID 10 with the others

bear in=C2=A0 mind that there is a calculation about guar= anteed failure of given RAID rebuild process when you exceed a certain amou= nt of terabytes capacity to rebuild

That is why enterprise storages with lot of terabytes are= always subdivided in the needed amount of RAID 5 or RAID 6 blocks to be ne= xt stack on RAID 50 or RAID 60

At recuperod= atiraidfastec.it we have seen so many cases of failed rebuilds due to l= eak of calculation before implementation

Kind regards

Roberto Gini
CTO @ https://www
Il giorno 10 lug 2023, alle ore 08:47, Tim 'mit= hro' Ansell <me@mith.ro<= /a>> ha scritto:
Hello!

RAID5 survives 1 disk failure an= d RAID6 survives 2 disk failures. What about going beyond 2 disk failures? = Does anyone know where I can find information on what good options might be= ?

I was looking at RAID10, but every extra mirror = added only increases failure tolerance by 1 disk. I am also not seeing any = inbuilt support in LVM for RAID50 or RAID60 but it seems like if I manually= build the sub-volumes, things should still be fine?

My system has 25 disks and I'd like to tolerate up to ~1/3rd of the disk= s failing so I was thinking that a RAID1 with 3 mirrors built out of RAID6 = with 8 disks each (and 1 hot spare) would be a potentially good option?

Thank you for your help!

Tim= 'mithro' Ansell




linux-lvm mailing list
linux-lvm@redhat.com<=
br>https:=
//listman.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO =
at http://tldp.org/HOWTO/LVM-HO=
WTO/
------Y9FYIY5QCBN53AQX6ETASQVLJCFK6Q-- --===============3588157545266290745== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ --===============3588157545266290745==--