143 lines
4.4 KiB
Plaintext
143 lines
4.4 KiB
Plaintext
---
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layout: default
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title: Setting up fresh disk for LVM
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date: 2023-08-28 22:58 +0200
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tags: disks LVM
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---
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Format, partition and create file system.
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* "SSD - Gentoo wiki":https://wiki.gentoo.org/wiki/SSD
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* "SSD - Archlinux wiki":https://wiki.archlinux.org/title/Solid_state_drive
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h2. System settings
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Disable issuing discards for SSD drives, so LVM operations will be undoable:
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{% highlight config caption=/etc/lvm/lvm.conf %}
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issue_discards = 0
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{% endhighlight %}
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h2. Setting logical sector size
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*Warning:* Changing sector size destroys all data.
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List current logical and physical sector sizes for block devices:
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{% highlight bash %}
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$ lsblk -dt
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NAME ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED RQ-SIZE RA WSAME
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sda 0 4096 0 4096 512 1 mq-deadline 2 128 0B
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nvme0n1 0 512 0 512 512 0 none 1023 128 0B
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{% endhighlight %}
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* for SATA drives: set logical sector size equal to physical (if supported)
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{% highlight bash %}
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# hdparm -I /dev/sda | grep 'Sector size:'
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Logical Sector size: 512 bytes [ Supported: 512 4096 ]
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Physical Sector size: 4096 bytes
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# hdparm --set-sector-size 4096 --please-destroy-my-drive /dev/sda
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{% endhighlight %}
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* for NVMe drives: set logical sector size based on relative performance
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{% highlight bash %}
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# nvme id-ns -H /dev/nvme0n1 | grep 'Relative Performance'
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LBA Format 0 : Metadata Size: 0 bytes - Data Size: 512 bytes - Relative Performance: 0x2 Good (in use)
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LBA Format 1 : Metadata Size: 0 bytes - Data Size: 4096 bytes - Relative Performance: 0x1 Better
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# nvme format --lbaf=1 /dev/nvme0n1
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{% endhighlight %}
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Further details: "Advanced format - Archlinux wiki":https://wiki.archlinux.org/title/Advanced_Format
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h2. Partitioning and LVM setup
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Parition alignment on 2MiB (equal to maximum possible Erase Block Size for
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SSD/NVMe drives) equivalent to 4096 sectors 512B each/512 sectors 4KiB each.
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{% highlight bash %}
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# sfdisk /dev/nvme0n1
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> label: gpt
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{% endhighlight %}
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Leave 2MiB of space at the beginning for parition table and (optionally)
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bootloader.
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For system drives, reserve 1022MiB EFI partition. Firmware updates
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use EFI partition and may require >100MiB.
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Remaining disk space is for LVM. For non-system drives, LVM partition starts at
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2MiB. Values given to @sfdisk@ are in *logical sectors* (as opposed to physical
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sectors, as they're not necessarily same size) and example below is using 4KiB
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logical sector size.
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{% highlight bash %}
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> 512, 261632, U, *
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> 262144, , V,
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> w
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> q
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# pvcreate --dataalignment 2M /dev/nvme0n1p2
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# pvs /dev/nvme0n1p2 -o+pe_start
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# vgcreate -s 1G vgdev /dev/nvme0n1p2
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{% endhighlight %}
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(verify that @pe_start@ is a multiple of alignment size).
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If you want to extend existing VG, see "here":{% post_url
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/sysadm/2023-09-15-lvm-cheat-sheet %}#convert-lv-to-raid1.
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h2. File system setup and mouning
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Create LV, optionally add redundancy/integrity layer ("details":{% post_url
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/sysadm/2023-06-24-directly-attache-storage-with-redundancy-and-integrity-using-lvm-lvmraid
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%}).
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{% highlight bash %}
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# lvcreate -L 2T -n backup --type raid1 --mirrors 1 vgdev
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# lvconvert --raidintegrity y --raidintegrityblocksize 4096 --raidintegritymode bitmap /dev/vgdev/backup
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{% endhighlight %}
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For ext4 file systems, block sizes availavle on _x86_ architectures are from
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4KiB to 64KiB.
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Disable journaling.
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For file systems on RAID devices other thatn RAID 1 (mirror), add _-E
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stride=512,stripe_width=512,_ options. Stride size/stripe width is given in file
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system block multiplies and should be aligned same as paritions (2MiB).
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_-E discard_ can be omitted as it is the default.
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{% highlight bash %}
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# mkfs.ext4 -b 4096 -O ^has_journal /dev/vgdev/backup
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{% endhighlight %}
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Use following mount options in _/etc/fstab_:
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* (for external disks) @noauto@
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* @noatime,errors=remount-ro@
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* (for SSD only) @nodiscard@ - discard on weekly basis using cron (make
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sure you're using _anacron_ on desktop):
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{% highlight bash caption=/etc/cron.weekly/fstrim %}
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#!/bin/bash
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/usr/bin/ionice -c 3 /sbin/fstrim -v -a
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{% endhighlight %}
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h2. Monitoring
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h3. LV RAID health status
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Make sure that cron messages are received, e.g. sent to proper e-mail address.
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{% highlight bash caption=/etc/cron.hourly/lv-health-status %}
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#!/bin/sh
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lvs -o full_name,lv_health_status --separator ':' | tail -n+2 | egrep -v ':[[:space:]]*$'
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{% endhighlight %}
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TODO: monitoring smartd with cron task.
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