On Tue, Apr 25, 2017 at 9:18 PM, Jim Kusznir <jim@palousetech.com> wrote:

So with arbiter, I actually only have two copies of data...Does arbiter have at least checksum or something to detect corruption of a copy? (like old RAID-4 disk configuration)?

Yes, the arbiter brick stores metadata information about the files to decide the good copy of data stored on the replicas in case of conflict.

Ok...Related question: Is there a way to set up an offsite gluster storage server to mirror the contents of my main server? As "fire" insurance basically? (eventually, I'd like to have an "offsite" DR cluster, but I don't have the resources or scale yet for that).

What I'd like to do is place a basic storage server somewhere else and have it sync any gluster data changes on a regular basis, and be usable to repopulate storage should I loose all of my current cluster (eg, a building fire or theft).

Yes, the geo-replication feature can help with that. There's a remote data sync feature introduced for gluster storage domains, that helps with this. You can set this up such that data from your storage domain is regularly synced to a remote gluster volume, while ensuring data consistency. The remote gluster volume does not have to a replica 3.

I find gluster has amazing power from what I hear, but I have a hard time finding documentation at "the right level" to be useful. I've found some very basic introductory guide, then some very advanced guides that require extensive knowledge of gluster already. Something in the middle to explain some of these questions (like arbitrar and migration strategies, geo-replication, etc; and how to deploy them) are absent (or at least, i haven't found them yet). I still feel like I'm using something I don't understand, and the only avenue I have to learn more is to ask questions here, as the docs aren't at an accessible level.

Thanks for the feedback. Are you looking at documentation on a use-case basis?

Thanks!
--Jim

On Mon, Apr 3, 2017 at 10:34 PM, Sahina Bose <sabose@redhat.com> wrote:

On Sat, Apr 1, 2017 at 10:32 PM, Jim Kusznir <jim@palousetech.com> wrote:
Thank you!

Here's the output of gluster volume info:
[root@ovirt1 ~]# gluster volume info

Volume Name: data
Type: Replicate
Volume ID: e670c488-ac16-4dd1-8bd3-e43b2e42cc59
Status: Started
Number of Bricks: 1 x (2 + 1) = 3
Transport-type: tcp
Bricks:
Brick1: ovirt1.nwfiber.com:/gluster/brick2/data
Brick2: ovirt2.nwfiber.com:/gluster/brick2/data
Brick3: ovirt3.nwfiber.com:/gluster/brick2/data (arbiter)
Options Reconfigured:
performance.strict-o-direct: on
nfs.disable: on
user.cifs: off
network.ping-timeout: 30
cluster.shd-max-threads: 6
cluster.shd-wait-qlength: 10000
cluster.locking-scheme: granular
cluster.data-self-heal-algorithm: full
performance.low-prio-threads: 32
features.shard-block-size: 512MB
features.shard: on
storage.owner-gid: 36
storage.owner-uid: 36
cluster.server-quorum-type: server
cluster.quorum-type: auto
network.remote-dio: enable
cluster.eager-lock: enable
performance.stat-prefetch: off
performance.io-cache: off
performance.read-ahead: off
performance.quick-read: off
performance.readdir-ahead: on
server.allow-insecure: on

Volume Name: engine
Type: Replicate
Volume ID: 87ad86b9-d88b-457e-ba21-5d3173c612de
Status: Started
Number of Bricks: 1 x (2 + 1) = 3
Transport-type: tcp
Bricks:
Brick1: ovirt1.nwfiber.com:/gluster/brick1/engine
Brick2: ovirt2.nwfiber.com:/gluster/brick1/engine
Brick3: ovirt3.nwfiber.com:/gluster/brick1/engine (arbiter)
Options Reconfigured:
performance.readdir-ahead: on
performance.quick-read: off
performance.read-ahead: off
performance.io-cache: off
performance.stat-prefetch: off
cluster.eager-lock: enable
network.remote-dio: off
cluster.quorum-type: auto
cluster.server-quorum-type: server
storage.owner-uid: 36
storage.owner-gid: 36
features.shard: on
features.shard-block-size: 512MB
performance.low-prio-threads: 32
cluster.data-self-heal-algorithm: full
cluster.locking-scheme: granular
cluster.shd-wait-qlength: 10000
cluster.shd-max-threads: 6
network.ping-timeout: 30
user.cifs: off
nfs.disable: on
performance.strict-o-direct: on

Volume Name: export
Type: Replicate
Volume ID: 04ee58c7-2ba1-454f-be99-26ac75a352b4
Status: Stopped
Number of Bricks: 1 x (2 + 1) = 3
Transport-type: tcp
Bricks:
Brick1: ovirt1.nwfiber.com:/gluster/brick3/export
Brick2: ovirt2.nwfiber.com:/gluster/brick3/export
Brick3: ovirt3.nwfiber.com:/gluster/brick3/export (arbiter)
Options Reconfigured:
performance.readdir-ahead: on
performance.quick-read: off
performance.read-ahead: off
performance.io-cache: off
performance.stat-prefetch: off
cluster.eager-lock: enable
network.remote-dio: off
cluster.quorum-type: auto
cluster.server-quorum-type: server
storage.owner-uid: 36
storage.owner-gid: 36
features.shard: on
features.shard-block-size: 512MB
performance.low-prio-threads: 32
cluster.data-self-heal-algorithm: full
cluster.locking-scheme: granular
cluster.shd-wait-qlength: 10000
cluster.shd-max-threads: 6
network.ping-timeout: 30
user.cifs: off
nfs.disable: on
performance.strict-o-direct: on

Volume Name: iso
Type: Replicate
Volume ID: b1ba15f5-0f0f-4411-89d0-595179f02b92
Status: Started
Number of Bricks: 1 x (2 + 1) = 3
Transport-type: tcp
Bricks:
Brick1: ovirt1.nwfiber.com:/gluster/brick4/iso
Brick2: ovirt2.nwfiber.com:/gluster/brick4/iso
Brick3: ovirt3.nwfiber.com:/gluster/brick4/iso (arbiter)
Options Reconfigured:
performance.readdir-ahead: on
performance.quick-read: off
performance.read-ahead: off
performance.io-cache: off
performance.stat-prefetch: off
cluster.eager-lock: enable
network.remote-dio: off
cluster.quorum-type: auto
cluster.server-quorum-type: server
storage.owner-uid: 36
storage.owner-gid: 36
features.shard: on
features.shard-block-size: 512MB
performance.low-prio-threads: 32
cluster.data-self-heal-algorithm: full
cluster.locking-scheme: granular
cluster.shd-wait-qlength: 10000
cluster.shd-max-threads: 6
network.ping-timeout: 30
user.cifs: off
nfs.disable: on
performance.strict-o-direct: on

The node marked as (arbiter) on all of the bricks is the node that is not using any of its disk space.

This is by design - the arbiter brick only stores metadata and hence saves on storage.

The engine domain is the volume dedicated for storing the hosted engine. Here's some LVM info:

--- Logical volume ---
LV Path /dev/gluster/engine
LV Name engine
VG Name gluster
LV UUID 4gZ1TF-a1PX-i1Qx-o4Ix-MjEf-0HD8-esm3wg
LV Write Access read/write
LV Creation host, time ovirt1.nwfiber.com, 2016-12-31 14:40:00 -0800
LV Status available
# open 1
LV Size 25.00 GiB
Current LE 6400
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2

--- Logical volume ---
LV Name lvthinpool
VG Name gluster
LV UUID aaNtso-fN1T-ZAkY-kUF2-dlxf-0ap2-JAwSid
LV Write Access read/write
LV Creation host, time ovirt1.nwfiber.com, 2016-12-31 14:40:09 -0800
LV Pool metadata lvthinpool_tmeta
LV Pool data lvthinpool_tdata
LV Status available
# open 4
LV Size 150.00 GiB
Allocated pool data 65.02%
Allocated metadata 14.92%
Current LE 38400
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:5

--- Logical volume ---
LV Path /dev/gluster/data
LV Name data
VG Name gluster
LV UUID NBxLOJ-vp48-GM4I-D9ON-4OcB-hZrh-MrDacn
LV Write Access read/write
LV Creation host, time ovirt1.nwfiber.com, 2016-12-31 14:40:11 -0800
LV Pool name lvthinpool
LV Status available
# open 1
LV Size 100.00 GiB
Mapped size 90.28%
Current LE 25600
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:7

--- Logical volume ---
LV Path /dev/gluster/export
LV Name export
VG Name gluster
LV UUID bih4nU-1QfI-tE12-ZLp0-fSR5-dlKt-YHkhx8
LV Write Access read/write
LV Creation host, time ovirt1.nwfiber.com, 2016-12-31 14:40:20 -0800
LV Pool name lvthinpool
LV Status available
# open 1
LV Size 25.00 GiB
Mapped size 0.12%
Current LE 6400
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:8

--- Logical volume ---
LV Path /dev/gluster/iso
LV Name iso
VG Name gluster
LV UUID l8l1JU-ViD3-IFiZ-TucN-tGPE-Toqc-Q3R6uX
LV Write Access read/write
LV Creation host, time ovirt1.nwfiber.com, 2016-12-31 14:40:29 -0800
LV Pool name lvthinpool
LV Status available
# open 1
LV Size 25.00 GiB
Mapped size 28.86%
Current LE 6400
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:9

--- Logical volume ---
LV Path /dev/centos_ovirt/swap
LV Name swap
VG Name centos_ovirt
LV UUID PcVQ11-hQ9U-9KZT-QPuM-HwT6-8o49-2hzNkQ
LV Write Access read/write
LV Creation host, time localhost, 2016-12-31 13:56:36 -0800
LV Status available
# open 2
LV Size 16.00 GiB
Current LE 4096
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1

--- Logical volume ---
LV Path /dev/centos_ovirt/root
LV Name root
VG Name centos_ovirt
LV UUID g2h2fn-sF0r-Peos-hAE1-WEo9-WENO-MlO3ly
LV Write Access read/write
LV Creation host, time localhost, 2016-12-31 13:56:36 -0800
LV Status available
# open 1
LV Size 20.00 GiB
Current LE 5120
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0

------------

I don't use the export gluster volume, and I've never used lvthinpool-type allocations before, so I'm not sure if there's anything special there.

I followed the setup instructions from an ovirt contributed documentation that I can't find now that talked about how to install ovirt with gluster on a 3-node cluster.

Thank you for your assistance!
--Jim

On Thu, Mar 30, 2017 at 1:27 AM, Sahina Bose <sabose@redhat.com> wrote:

On Thu, Mar 30, 2017 at 1:23 PM, Liron Aravot <laravot@redhat.com> wrote:
Hi Jim, please see inline

On Thu, Mar 30, 2017 at 4:08 AM, Jim Kusznir <jim@palousetech.com> wrote:
hello:

I've been running my ovirt Version 4.0.5.5-1.el7.centos cluster for a while now, and am now revisiting some aspects of it for ensuring that I have good reliability.

My cluster is a 3 node cluster, with gluster nodes running on each node. After running my cluster a bit, I'm realizing I didn't do a very optimal job of allocating the space on my disk to the different gluster mount points. Fortunately, they were created with LVM, so I'm hoping that I can resize them without much trouble.

I have a domain for iso, domain for export, and domain for storage, all thin provisioned; then a domain for the engine, not thin provisioned. I'd like to expand the storage domain, and possibly shrink the engine domain and make that space also available to the main storage domain. Is it as simple as expanding the LVM partition, or are there more steps involved? Do I need to take the node offline?

I didn't understand completely that part - what is the difference between the domain for storage and the domain for engine you mentioned?

I think the domain for engine is the one storing Hosted Engine data.
You should be able to expand your underlying LVM partition without having to take the node offline

second, I've noticed that the first two nodes seem to have a full copy of the data (the disks are in use), but the 3rd node appears to not be using any of its storage space...It is participating in the gluster cluster, though.

Is the volume created as replica 3? If so, fully copy of the data should be present on all 3 nodes. Please provide the output of "gluster volume info"

Third, currently gluster shares the same network as the VM networks. I'd like to put it on its own network. I'm not sure how to do this, as when I tried to do it at install time, I never got the cluster to come online; I had to make them share the same network to make that work.

While creating the bricks the network intended for gluster should have been used to identify the brick in hostname:brick-directory. Changing this at a later point is a bit more involved. Please check online or on gluster-users on changing IP address associated with brick.

I'm adding Sahina who may shed some light on the gluster question, I'd try on the gluster mailing list as well.

Ovirt questions:
I've noticed that recently, I don't appear to be getting software updates anymore. I used to get update available notifications on my nodes every few days; I haven't seen one for a couple weeks now. is something wrong?

I have a windows 10 x64 VM. I get a warning that my VM type does not match the installed OS. All works fine, but I've quadrouple-checked that it does match. Is this a known bug?

Arik, any info on that?

I have a UPS that all three nodes and the networking are on. It is a USB UPS. How should I best integrate monitoring in? I could put a raspberry pi up and then run NUT or similar on it, but is there a "better" way with oVirt?

Thanks!
--Jim

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