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2023-09-04 01:49:23 +02:00 · 2023-09-04 01:49:23 +02:00 · eb6f8ed8e9
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+---
+layout: default
+title: Setting up fresh disk for LVM
+date: 2023-08-28 22:58 +0200
+tags: disks LVM
+---
+Format, partition and create file system.
+
+* "Gentoo wiki - SSD":https://wiki.gentoo.org/wiki/SSD
+* "Archlinux wiki - SSD":https://wiki.archlinux.org/title/Solid_state_drive
+
+
+h2. System settings
+
+Disable issuing discards for SSD drives, so LVM operations will be undoable:
+
+{% highlight config caption=/etc/lvm/lvm.conf %}
+issue_discards = 0
+{% endhighlight %}
+
+
+h2. Setting logical sector size
+
+*Warning:* Changing sector size destroys all data.
+
+List current logical and physical sector sizes for block devices:
+{% highlight bash %}
+$ lsblk -dt
+NAME    ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED       RQ-SIZE  RA WSAME
+sda             0   4096      0    4096     512    1 mq-deadline       2 128    0B
+nvme0n1         0    512      0     512     512    0 none           1023 128    0B
+{% endhighlight %}
+
+* for SATA drives: set logical sector size equal to physical (if supported)
+
+{% highlight bash %}
+# hdparm -I /dev/sda | grep 'Sector size:'
+Logical  Sector size:                   512 bytes [ Supported: 512 4096 ]
+Physical Sector size:                  4096 bytes
+# hdparm --set-sector-size 4096 --please-destroy-my-drive  /dev/sda
+{% endhighlight %}
+
+* for NVMe drives: set logical sector size based on relative performance
+
+{% highlight bash %}
+# nvme id-ns -H /dev/nvme0n1 | grep 'Relative Performance'
+LBA Format  0 : Metadata Size: 0   bytes - Data Size: 512 bytes - Relative Performance: 0x2 Good (in use)
+LBA Format  1 : Metadata Size: 0   bytes - Data Size: 4096 bytes - Relative Performance: 0x1 Better
+# nvme format --lbaf=1 /dev/nvme0n1
+{% endhighlight %}
+
+Further details: "Archlinux wiki - Advanced format":https://wiki.archlinux.org/title/Advanced_Format
+
+
+h2. Partitioning and LVM setup
+
+Parition alignment on 2MiB (equal to maximum possible Erase Block Size for
+SSD/NVMe drives) equivalent to 4096 sectors 512B each/512 sectors 4KiB each.
+
+{% highlight bash %}
+# sfdisk /dev/nvme0n1
+> label: gpt
+{% endhighlight %}
+
+Leave 2MiB of space at the beginning for parition table and (optionally)
+bootloader.
+
+For system drives, reserve 1022MiB EFI partition. Firmware updates
+use EFI partition and may require >100MiB.
+
+Remaining disk space is for LVM.  For non-system drives, LVM partition starts at
+2MiB. Values given to @sfdisk@ are in *logical sectors* (as opposed to physical
+sectors, as they're not necessarily same size) and example below is using 4KiB
+logical sector size.
+
+{% highlight bash %}
+> 512, 261632, U, *
+> 262144, , V,
+> w
+> q
+
+# pvcreate --dataalignment 2M /dev/nvme0n1p2
+# pvs /dev/nvme0n1p2 -o+pe_start
+# vgcreate -s 1G vgdev /dev/nvme0n1p2
+{% endhighlight %}
+
+(verify that @pe_start@ is a multiple of alignment size).
+
+
+h2. File system setup and mouning
+
+Create LV, optionally add redundancy/integrity layer
+("details":https://blog.michalczyk.pro/2023/06/24/directly-attache-storage-with-redundancy-and-integrity-using-lvm-lvmraid.html).
+
+{% highlight bash %}
+# lvcreate -L 2T -n backup vgdev
+# lvconvert --raidintegrity y --raidintegrityblocksize 4096 --raidintegritymode bitmap /dev/vgdev/backup
+{% endhighlight %}
+
+For ext4 file systems, block sizes availavle on _x86_ architectures are from
+4KiB to 64KiB.
+
+Disable journaling.
+
+For file systems on RAID devices other thatn RAID 1 (mirror), add _-E
+stride=512,stripe_width=512,_ options. Stride size/stripe width is given in file
+system block multiplies and should be aligned same as paritions (2MiB).
+
+_-E discard_ can be omitted as it is the default.
+
+{% highlight bash %}
+# mkfs.ext4 -b 4096 -O ^has_journal /dev/vgdev/backup
+{% endhighlight %}
+
+Use following mount options in _/etc/fstab_:
+* (for external disks) @noauto@
+* @noatime,errors=remount-ro@
+* (for SSD only) @nodiscard@ - discard on weekly basis using cron (make
+sure you're using _anacron_ on desktop):
+
+{% highlight bash caption=/etc/cron.weekly/fstrim %}
+#!/bin/bash
+/usr/bin/ionice -c 3 /sbin/fstrim -a
+{% endhighlight %}
+
+
+h2. Monitoring
+
+TODO: monitoring smartd and RAID status with cron task.