04/04: berlin: Migrate root file system to SAN storage.

[Maxim Cournoyer]

apteryx pushed a commit to branch wip-san-migration
in repository maintenance.

commit ea4526070eb939da84d0a37e3b23e0a2d1b86b1f
Author: Maxim Cournoyer <maxim.cournoyer@gmail.com>
AuthorDate: Fri Jul 29 15:19:46 2022 -0400

    berlin: Migrate root file system to SAN storage.
    
    Farewell, inodes exhaustion...
---
 hydra/berlin.scm | 99 +++++++++++++++++++++++---------------------------------
 1 file changed, 40 insertions(+), 59 deletions(-)

diff --git a/hydra/berlin.scm b/hydra/berlin.scm
index 851d233..1babce2 100644
--- a/hydra/berlin.scm
+++ b/hydra/berlin.scm
@@ -170,13 +170,16 @@ Happy hacking!\n"))
 
 
 ;;;
-;;; Btrfs RAID10 array.
+;;;  Btrfs pools.
 ;;;
 ;;; This Btrfs storage array is composed of six (6) Samsung 870 QVO
 ;;; SSDs of 8 TB each; configured to use the raid1c4 Btrfs profile for
 ;;; metadata and raid10 for data.
+(define %btrfs-ssd-uuid "16ff18e1-eb41-4224-8df6-80d3b53c411a")
 
-(define %btrfs-raid-uuid "16ff18e1-eb41-4224-8df6-80d3b53c411a")
+;;; This is one large Btrfs partition on the MDC-provided SAN storage
+;;; (100 TiB).
+(define %btrfs-san-uuid "d5d1a040-7f2a-4c38-9a89-82f08866f6ec")
 
 ;;; TODO: Implement some mcron job that monitors the absent of a disk
 ;;; in the array, or IO related errors in dmesg, so that we can notice
@@ -185,48 +188,37 @@ Happy hacking!\n"))
                                 ("space_cache" . "v2")
                                 "degraded"))
 
-;;; Top-level Btrfs subvolume.
-(define %btrfs-pool
+(define %btrfs-pool-san
   (file-system
     ;; This is required by the 'btrbk' backup tool.
-    (device (uuid %btrfs-raid-uuid))
-    (mount-point "/mnt/btrfs-pool")
+    (device (uuid %btrfs-san-uuid))
+    (mount-point "/mnt/btrfs-pool-san")
     (type "btrfs")
     (options (alist->file-system-options
               (cons '("subvolid" . "5")
                     %common-btrfs-options)))))
 
-;;; Root Btrfs subvolume.
-(define @root
+(define %btrfs-pool-ssd
   (file-system
-    (device (uuid %btrfs-raid-uuid))
-    (mount-point "/new-root")
+    ;; This is required by the 'btrbk' backup tool.
+    (device (uuid %btrfs-ssd-uuid))
+    (mount-point "/mnt/btrfs-pool-ssd")
     (type "btrfs")
     (options (alist->file-system-options
-              (cons '("subvol" . "@root")
+              (cons '("subvolid" . "5")
                     %common-btrfs-options)))))
 
-;;; Home Btrfs subvolume.
-(define @home
+(define (btrfs-subvolume-mount device-uuid name mount-point)
+  "Return a file system to mount the Btrfs subvolume NAME on DEVICE-UUID
+at MOUNT-POINT."
   (file-system
-    (device (uuid %btrfs-raid-uuid))
-    (mount-point "/home")
+    (device (uuid device-uuid))
+    (mount-point mount-point)
+    (create-mount-point? #t)
     (type "btrfs")
     (options (alist->file-system-options
-              (cons '("subvol" . "@home")
-                    %common-btrfs-options)))
-    (dependencies (list @root))))
-
-;;; Cache Btrfs subvolume.
-(define @cache
-  (file-system
-    (device (uuid %btrfs-raid-uuid))
-    (mount-point "/var/cache")
-    (type "btrfs")
-    (options (alist->file-system-options
-              (cons '("subvol" . "@cache")
-                    %common-btrfs-options)))
-    (dependencies (list @root))))
+              (cons (cons "subvol" name)
+                    %common-btrfs-options)))))
 
 (define (anonip-service file)
   (service anonip-service-type
@@ -245,18 +237,15 @@ Happy hacking!\n"))
   ;; management interface can only be accessed through selected
   ;; servers within the MDC campus network.
   (kernel-arguments '("console=tty0"
-                      "console=ttyS0,115200"
-                      ;; As the initrd lacks any device
-                      ;; synchronization support, give enough time for
-                      ;; the storage devices to be up before
-                      ;; attempting to assemble and mount the root
-                      ;; file system.
-                      "rootdelay=20"))
+                      "console=ttyS0,115200"))
 
   ;; The Dell server need these kernel modules for the
   ;; RAID controller.
   (initrd-modules (append (list "megaraid_sas" "scsi_transport_sas"
-                                "mpt3sas" "libsas")
+                                "mpt3sas" "libsas"
+                                ;; Suggested by 'guix system init' for
+                                ;; the SAN storage.
+                                "qla2xxx")
                           %base-initrd-modules))
 
   ;; Show the GRUB menu on the serial interface.
@@ -271,30 +260,22 @@ Happy hacking!\n"))
                   (mount-point "/boot/efi")
                   (device (uuid "E1B3-BF92" 'fat)) ;/dev/sdi1
                   (type "vfat"))
-                 ;; The root file system resides on just a single
-                 ;; disk, no RAID :-/
-                 (file-system
-                   (device (file-system-label "my-root"))
-                   (mount-point "/")
-                   (type "ext4"))
-                 ;; This is a large external storage array
-                 ;; connected via 2 HBA cards.  We only mount it
-                 ;; through one of the HBA cards.  We would need
-                 ;; to use multipathd otherwise.
+
+                 (btrfs-subvolume-mount %btrfs-san-uuid "@root" "/")
+
+                 (btrfs-subvolume-mount %btrfs-ssd-uuid "@home" "/home")
+                 (btrfs-subvolume-mount %btrfs-ssd-uuid "@cache" "/var/cache")
+
+                 ;; For convenience.
+                 %btrfs-pool-san
+                 %btrfs-pool-ssd
                  (file-system
-                   (device (uuid "a6455b66-59d2-40bd-bddb-0c572bb62a2f"))
-                   (mount-point "/gnu")
+                   ;; This is device holding the old root file system,
+                   ;; /dev/sdg1.
+                   (device (uuid "76954008-06cf-4b91-b0bb-316d8bab0576"))
+                   (mount-point "/mnt/old-root-fs")
                    (type "ext4"))
-                 ;; Access root file system without bind mounts.
-                 (file-system
-                   (device "/")
-                   (mount-point "/mnt/root-fs")
-                   (flags '(bind-mount))
-                   (type "none"))
-                 %btrfs-pool
-                 @root
-                 @home
-                 @cache
+
                  %base-file-systems))
 
   ;; Local admin account for MDC maintenance.