Changes between Version 1 and Version 2 of ssd

Timestamp:

Sep 25, 2016, 7:24:19 PM (9 years ago)

Author:

Jamie McClelland

Comment:

--

ssd

@@ -26 +26 @@
 Due to limitations of SSD, the operating system must communicate to the disk which sectors are free for writing (trim/discards), we have to configure all the disk layers specifically to pass these "disard" messages.
 
-
+== Technical Details ==
+
+Following are the steps for adding a solid state drive to both a host and a guest
+
+=== Adding solid state drives to a host ===
+
+First, order the disks (see [ticket:11870#comment:7 previous SSDs we have purchased] and order the cables and cages needed to install them (see [ticket:11870#comment:10 previous cables we have ordered]).
+
+Once installed, the should show up via `cat /proc/partitions` as something like /dev/sda and /dev/sdb.
+
+Next, modify the physical servers .pp file in puppet, changing the call to m_physical server to be:
+
+{{{
+class { "mayfirst::m_physical": 
+  ssd => true
+}
+}}}
+
+Once you push, it should change /etc/lvm/lvm.conf to have: `issue_discards = 1`
+
+Next, create a single partition on each device, e.g.:
+
+{{{
+0 wiwa:/etc/lvm# parted /dev/sdb
+GNU Parted 3.2
+Using /dev/sdb
+Welcome to GNU Parted! Type 'help' to view a list of commands.
+(parted) mklabel gpt
+(parted) unit s mkpart main 8192 -196608                                       
+(parted) p                                                                
+Model: ATA SAMSUNG MZ7KM480 (scsi)
+Disk /dev/sdb: 937703088s
+Sector size (logical/physical): 512B/512B
+Partition Table: gpt
+Disk Flags: 
+
+Number  Start  End         Size        File system  Name  Flags
+ 1      8192s  937506480s  937498289s               main
+
+(parted) 
+}}}
+
+Then a RAID 1 array:
+
+{{{
+mdadm --create --raid-devices=2 --level=1 --metadata=1.0 --verbose /dev/md2 /dev/sda1 /dev/sdb1
+}}}
+
+Scan your RAID devices:
+
+{{{
+mdadm --examine --scan
+}}}
+
+And based on the output, edit /etc/mdadm/mdam.conf to add a line for your new RAID (something like: `ARRAY /dev/md/2  metadata=1.0 UUID=70345fc6:661e67ce:715261cf:84112f10 name=wiwa:2`
+
+Now, setup encryption and be sure to enable `--allow-discards`:
+
+{{{
+0 wiwa:/etc/lvm# cryptsetup luksFormat /dev/md2 
+
+WARNING!
+========
+This will overwrite data on /dev/md2 irrevocably.
+
+Are you sure? (Type uppercase yes): YES
+Enter passphrase: 
+Verify passphrase: 
+0 wiwa:/etc/lvm# cryptsetup --allow-discards luksOpen /dev/md2 md2_crypt
+Enter passphrase for /dev/md2: 
+0 wiwa:/etc/lvm# blkid /dev/md2 
+/dev/md2: UUID="b360ef4f-84ea-457c-8f86-a7f94b1f9277" TYPE="crypto_LUKS"
+0 wiwa:/etc/lvm# echo md2_crypt UUID=b360ef4f-84ea-457c-8f86-a7f94b1f9277 none luks,discard >> /etc/crypttab 
+0 wiwa:/etc/lvm# cat /etc/crypttab 
+# <target name> <source device>         <key file>      <options>
+md1_crypt UUID=ae7a55a5-cc91-4064-8e5f-06eb293188a2 none luks
+md2_crypt UUID=b360ef4f-84ea-457c-8f86-a7f94b1f9277 none luks,discard
+0 wiwa:/etc/lvm#  pvcreate /dev/mapper/md2_crypt 
+  Physical volume "/dev/mapper/md2_crypt" successfully created
+0 wiwa:/etc/lvm# vgcreate vg_wiwa1 /dev/mapper/md2_crypt 
+  Volume group "vg_wiwa1" successfully created
+0 wiwa:/etc/lvm#
+}}}
+
+=== Adding solid state drives to a guest ===
+
+On the host, create a logical volume for your given host, e.g.:
+
+{{{
+0 wiwa:/etc/lvm# lvcreate --size 10GB --name jacobs vg_wiwa1
+  Logical volume "jacobs" created
+0 wiwa:/etc/lvm#
+}}}
+
+Change the group ownership to match the user the guests runs as:
+
+{{{
+1 wiwa:/etc/sv/kvm/jacobs# ls -l /dev/mapper/vg_wiwa1-jacobs 
+lrwxrwxrwx 1 root root 8 Sep 23 15:16 /dev/mapper/vg_wiwa1-jacobs -> ../dm-28
+0 wiwa:/etc/sv/kvm/jacobs# chgrp jacobs /dev/dm-28
+0 wiwa:/etc/sv/kvm/jacobs#
+}}}
+
+Reboot the guest.
+
+From the guest...
+
+Look for the new block device (/dev/sdb below):
+
+{{{
+0 jacobs:~# cat /proc/partitions 
+major minor  #blocks  name
+
+   8       16   10485760 sdb
+   8        0  524288000 sda
+   8        1     248832 sda1
+   8        2  524037120 sda2
+ 254        0    3997696 dm-0
+ 254        1     499712 dm-1
+ 254        2     999424 dm-2
+ 254        3    4997120 dm-3
+ 254        4    4997120 dm-4
+ 254        5   20971520 dm-5
+0 jacobs:~#
+}}}
+
+Create a single partition:
+
+{{{
+0 jacobs:~# parted /dev/sdb
+GNU Parted 3.2
+Using /dev/sdb
+Welcome to GNU Parted! Type 'help' to view a list of commands.
+(parted) mklabel gpt                                                      
+(parted) unit s mkpart main 8192 -196608                                  
+(parted) p                                                                
+Model: QEMU QEMU HARDDISK (scsi)
+Disk /dev/sdb: 20971520s
+Sector size (logical/physical): 512B/512B
+Partition Table: gpt
+Disk Flags: 
+
+Number  Start  End        Size       File system  Name  Flags
+ 1      8192s  20774912s  20766721s               main
+
+(parted) quit                                                             
+Information: You may need to update /etc/fstab.
+
+0 jacobs:~#
+}}}
+
+Create a filesystem:
+
+{{{
+mkfs -t ext4 /dev/sdb1
+}}}
+
+==== Replacing MySQL partition ====
+
+If you are using this partition to replace MySQL...
+
+Stop mysql:
+
+{{{
+systemctl stop mysql
+}}}
+
+Unmount /var/lib/mysql:
+
+{{{
+umount /var/lib/mysql
+}}}
+
+Edit /etc/fstab, change the line for mounting /var/lib/mysql to match /dev/sdb1 instead of the existing logical volume.
+
+Mount the old logical volume on /mnt:
+
+{{{
+mount /dev/mapper/vg_jacobs0-var+lib+mysql /mnt
+}}}
+
+Mount the new partition:
+
+{{{
+mount /var/lib/mysql
+}}}
+
+Move the data:
+
+{{{
+mv /mnt/* /var/lib/mysql
+}}}
+
+Umount /mnt and remove the logical volume:
+
+{{{
+umount /mnt
+lvremove /dev/mapper/vg_jacobs0-var+lib+mysql
+}}}
+
+Retart mysql:
+
+{{{
+systemctl start mysql
+}}}