[TriLUG] Help on disk managment: LVM vs. ZFS
Lee Fickenscher via TriLUG
trilug at trilug.org
Wed May 24 12:10:08 EDT 2017
Our ZoL experience was more recent (about the last month or so) but similar
to Ron's. Performance compared to XFS on LVM was horrible.
We didn't feel comfortable going to BTRFS but we needed some of the
features of ZFS/BTRFS so we considered using BSD or a Illumos instead. In
the end we went with XFS on ZoL which gave us better performance than
straight ZFS while only affecting features that we didn't care about.
In your case, I'd delete all the partitions on the external drive and put
LVM directly on the device so that volumes can be managed without using
fdisk or parted. That gives you the flexibility similar to what ZFS
provides and in your use case you aren't likely to get much out of the
other ZFS features.
As to your last question, lvcreate would be your next step, but like I
said, I'd start from scratch and let LVM manage the disk directly.
-Lee
On Wed, May 24, 2017 at 8:52 AM, mr-trilug via TriLUG <trilug at trilug.org>
wrote:
> My system:
> Ubuntu 16.04
> LXDE installed
>
> HD.1 750 GB as LVM with root, home, swap sections, in Samsung RV515
> laptop
>
> and for backup and additional storage:
> HD.2 320 GB, 4 partitions
> or --- one at a time goes in external HD case
> HD.3 120 GB LVM with 2 sections (but not yet recognized or
> mountable.
>
> Q1: Would I benefit from installing ZFS to use instead of LVM?
>
> "ZFS is a combinedfile system <https://en.wikipedia.org/wiki/File_system>andlogical
> volume manager <https://en.wikipedia.org/wiki/Logical_volume_management>
> "Zettabyte File System" ZFS does away with partitioning, EVMS, LVM, MD,
> etc. The available disks (of any size) are used to the best of their
> ability. Compression can be used to increase bandwidth. (q.v. Reiser 4, and
> cloop?)"
> cf.: https://wiki.ubuntu.com/ZFS
>
> Q2: How to progress from status, below, to a mountable status (pv and vg
> exist but lv does not)
>
> fdisk outpu:
>
> Disk /dev/sdb: 110.4 GiB, 118526284800 bytes, 231496650 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos
> Disk identifier: 0xd389a7da
>
> Device Boot Start End Sectors Size Id Type
> /dev/sdb1 2048 115000000 114997953 54.9G 8e Linux LVM
> /dev/sdb2 115001344 231496649 116495306 55.6G 8e Linux LVM
>
>
> lvm output
>
> --- Physical volume ---
> PV Name /dev/sdb1
> VG Name 120g-vg
> PV Size 54.84 GiB / not usable 3.34 MiB
> Allocatable yes
> PE Size 4.00 MiB
> Total PE 14037
> Free PE 14037
> Allocated PE 0
> PV UUID 1xzJUw-vhbS-kLMc-IjtT-bLtm-WeqM-NFH4Ty
>
> --- Physical volume ---
> PV Name /dev/sdb2
> VG Name 120g-vg
> PV Size 55.55 GiB / not usable 2.47 MiB
> Allocatable yes
> PE Size 4.00 MiB
> Total PE 14220
> Free PE 14220
> Allocated PE 0
> PV UUID fN0ide-WeXH-uJex-z4nQ-nyUo-ZSeK-VfrIJw
>
>
> --- Volume group ---
> VG Name 120g-vg
> System ID
> Format lvm2
> Metadata Areas 2
> Metadata Sequence No 1
> VG Access read/write
> VG Status resizable
> MAX LV 0
> Cur LV 0
> Open LV 0
> Max PV 0
> Cur PV 2
> Act PV 2
> VG Size 110.38 GiB
> PE Size 4.00 MiB
> Total PE 28257
> Alloc PE / Size 0 / 0
> Free PE / Size 28257 / 110.38 GiB
> VG UUID 7b1yjA-MW9S-zcwX-e8MO-y7BP-YCPs-HGDqlP
>
> ===============
> Michael Rulison
> 919 205 9168 (mobile phone)
> 3256 LEWIS FARM RD, RALEIGH NC 27607-6723
>
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