3:14 a.m.
My current hyperconverged environment is replicating data across all 3 servers.
I'm running critically low on disk space, and need to add space.
To that end, I've ordered 8x 800GB ssd drives, and plan to put 4 drives in 1 server,
and 4 drives in the other.
What's my best option for reconfiguring the hyperconverged cluster, to change gluster
storage away from Replica 3 to a Replica 2 / Arbiter model?
I'd really prefer not to have to reinstall things from scratch, but I'll do that
if I have to.
My most important requirement is that I cannot have any downtime for my VMs (so I can only
reconfigure 1 host at a time).
Sent with ProtonMail Secure Email.
12:55 p.m.
New subject: Reconfigure Gluster from Replica 3 to Arbiter 1/Replica 2
Hi David,
any storage operation can cause unexpected situations, so always plan your activites for
low traffic hours and test them on your test environment in advance.
I think it's easier if you (command line):
-verify no heals are pending. Not a single one.- set the host to maintenance over ovirt-
remove the third node from gluster volumes (remove-brick replica 2)- umount the bricks on
the third node- recreate a smaller LV with '-i maxpct=90 size=512' and mount it
with the same options like the rest of the nodes. Usually I use
'noatime,inode64,context=system_u:object_r:glusterd_brick_t:s0'- add this new
brick (add-brick replica 3 arbiter 1) to the volume- wait for the heals to finish
Then repeat again for each volume.
Adding the new disks should be done later.
Best Regards,Strahil Nikolov
On Sat, Jul 10, 2021 at 3:15, David White via Users<users(a)ovirt.org> wrote: My
current hyperconverged environment is replicating data across all 3 servers.
I'm running critically low on disk space, and need to add space.
To that end, I've ordered 8x 800GB ssd drives, and plan to put 4 drives in 1 server,
and 4 drives in the other.
What's my best option for reconfiguring the hyperconverged cluster, to change gluster
storage away from Replica 3 to a Replica 2 / Arbiter model?
I'd really prefer not to have to reinstall things from scratch, but I'll do that
if I have to.
My most important requirement is that I cannot have any downtime for my VMs (so I can only
reconfigure 1 host at a time).
Sent with ProtonMail Secure Email.
_______________________________________________
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To unsubscribe send an email to users-leave(a)ovirt.org
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1:14 p.m.
Thank you. And yes, I agree, this needs to occur in a maintenance window and be done very
carefully. :)
My only problem with this method is that I need to *replace* disks in the two servers.
I don't have any empty hard drive bays, so will effectively need to put a host into
maintenance mode, remove the drives, and put new drives in.
I will NOT be touching the OS drives, however, as those are on their own separate RAID
array.
So, essentially, it will need to look something like this:
- Put the cluster into global maintenance mode
- Put 1 host into full maintenance mode / deactivate it
- Stop gluster
- Remove the storage
- Add the new storage & reconfigure
- Start gluster
- Re-add the host to the cluster
Adding the new storage & reconfiguring is the head scratcher for me, given that I
don't have room for the old hard drives + new hard drives at the same time.
Sent with ProtonMail Secure Email.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, July 10th, 2021 at 5:55 AM, Strahil Nikolov <hunter86_bg(a)yahoo.com>
wrote:
Hi David,
any storage operation can cause unexpected situations, so always plan
your activites for low traffic hours and test them on your test environment in advance.
I think it's easier if you (command line):
-verify no heals are pending. Not a single one.- set the host to
maintenance over ovirt- remove the third node from gluster volumes (remove-brick replica
2)- umount the bricks on the third node- recreate a smaller LV with '-i maxpct=90
size=512' and mount it with the same options like the rest of the nodes. Usually I use
'noatime,inode64,context=system_u:object_r:glusterd_brick_t:s0'- add this new
brick (add-brick replica 3 arbiter 1) to the volume- wait for the heals to finish
Then repeat again for each volume.
Adding the new disks should be done later.
Best Regards,Strahil Nikolov
> On Sat, Jul 10, 2021 at 3:15, David White via
Users<users(a)ovirt.org> wrote:My current hyperconverged environment is replicating
data across all 3 servers.
> I'm running critically low on disk space, and need to add space.
>
> To that end, I've ordered 8x 800GB ssd drives, and plan to
put 4 drives in 1 server, and 4 drives in the other.
>
> What's my best option for reconfiguring the hyperconverged
cluster, to change gluster storage away from Replica 3 to a Replica 2 / Arbiter model?
> I'd really prefer not to have to reinstall things from scratch, but I'll do
that if I have to.
>
> My most important requirement is that I cannot have any downtime
for my VMs (so I can only reconfigure 1 host at a time).
>
> Sent with ProtonMail Secure Email.
>
> _______________________________________________
>
> Users mailing list -- users(a)ovirt.org
>
> To unsubscribe send an email to users-leave(a)ovirt.org
>
> Privacy Statement: https://www.ovirt.org/privacy-policy.html
>
> oVirt Code of Conduct:
https://www.ovirt.org/community/about/community-guidelines/
>
1:18 p.m.
Hmm.... right as I said that, I just had a thought.
I DO have a "backup" server in place (that I haven't even started using
yet), that currently has some empty hard drive bays.
It would take some extra work, but I could use that 4th backup server as a temporary
staging ground to begin building the new Gluster configuration. Once I have that server +
2 of my production servers rebuilt properly, I could then simply remove and replace this
"backup" server with my 3rd server in the cluster.
So this effectively means that I have 2 servers that I can take down completely at a
single time to rebuild gluster, instead of just 1. I think that simplifies things.
Sent with ProtonMail Secure Email.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, July 10th, 2021 at 6:14 AM, David White <dmwhite823(a)protonmail.com>
wrote:
Thank you. And yes, I agree, this needs to occur in a maintenance
window and be done very carefully. :)
My only problem with this method is that I need to *replace* disks in
the two servers.
I don't have any empty hard drive bays, so will effectively need to put a host into
maintenance mode, remove the drives, and put new drives in.
I will NOT be touching the OS drives, however, as those are on their
own separate RAID array.
So, essentially, it will need to look something like this:
- Put the cluster into global maintenance mode
- Put 1 host into full maintenance mode / deactivate it
- Stop gluster
- Remove the storage
- Add the new storage & reconfigure
- Start gluster
- Re-add the host to the cluster
Adding the new storage & reconfiguring is the head scratcher for
me, given that I don't have room for the old hard drives + new hard drives at the same
time.
Sent with ProtonMail Secure Email.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, July 10th, 2021 at 5:55 AM, Strahil Nikolov
<hunter86_bg(a)yahoo.com> wrote:
> Hi David,
>
> any storage operation can cause unexpected situations, so always
plan your activites for low traffic hours and test them on your test environment in
advance.
>
> I think it's easier if you (command line):
>
> -verify no heals are pending. Not a single one.- set the host to
maintenance over ovirt- remove the third node from gluster volumes (remove-brick replica
2)- umount the bricks on the third node- recreate a smaller LV with '-i maxpct=90
size=512' and mount it with the same options like the rest of the nodes. Usually I use
'noatime,inode64,context=system_u:object_r:glusterd_brick_t:s0'- add this new
brick (add-brick replica 3 arbiter 1) to the volume- wait for the heals to finish
>
> Then repeat again for each volume.
>
> Adding the new disks should be done later.
>
> Best Regards,Strahil Nikolov
>
> > On Sat, Jul 10, 2021 at 3:15, David White via
Users<users(a)ovirt.org> wrote:My current hyperconverged environment is replicating
data across all 3 servers.
> > I'm running critically low on disk space, and need to add space.
> >
> > To that end, I've ordered 8x 800GB ssd drives, and plan
to put 4 drives in 1 server, and 4 drives in the other.
> >
> > What's my best option for reconfiguring the
hyperconverged cluster, to change gluster storage away from Replica 3 to a Replica 2 /
Arbiter model?
> > I'd really prefer not to have to reinstall things from scratch, but
I'll do that if I have to.
> >
> > My most important requirement is that I cannot have any
downtime for my VMs (so I can only reconfigure 1 host at a time).
> >
> > Sent with ProtonMail Secure Email.
> >
> > _______________________________________________
> >
> > Users mailing list -- users(a)ovirt.org
> >
> > To unsubscribe send an email to users-leave(a)ovirt.org
> >
> > Privacy Statement:
https://www.ovirt.org/privacy-policy.html
> >
> > oVirt Code of Conduct:
https://www.ovirt.org/community/about/community-guidelines/
> >
> > List Archives:
https://lists.ovirt.org/archives/list/users@ovirt.org/message/YHEAXRUNA2R...
1:53 p.m.
New subject: Reconfigure Gluster from Replica 3 to Arbiter 1/Replica 2
Just a thought but depending on resources you might be able to use your 4th
server as nfs storage and live migrate vm disks to it and off of your
gluster volumes. I’ve done this in the past when doing major maintenance on
gluster volumes to err on the side of caution.
On Sat, Jul 10, 2021 at 7:22 AM David White via Users <users(a)ovirt.org>
wrote:
Hmm.... right as I said that, I just had a thought.
I DO have a "backup" server in place (that I haven't even started using
yet), that currently has some empty hard drive bays.
It would take some extra work, but I could use that 4th backup server as a
temporary staging ground to begin building the new Gluster configuration.
Once I have that server + 2 of my production servers rebuilt properly, I
could then simply remove and replace this "backup" server with my 3rd
server in the cluster.
So this effectively means that I have 2 servers that I can take down
completely at a single time to rebuild gluster, instead of just 1. I think
that simplifies things.
Sent with ProtonMail <https://protonmail.com/> Secure Email.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, July 10th, 2021 at 6:14 AM, David White <
dmwhite823(a)protonmail.com> wrote:
Thank you. And yes, I agree, this needs to occur in a maintenance window
and be done very carefully. :)
My only problem with this method is that I need to *replace* disks in the
two servers.
I don't have any empty hard drive bays, so will effectively need to put a
host into maintenance mode, remove the drives, and put new drives in.
I will NOT be touching the OS drives, however, as those are on their own
separate RAID array.
So, essentially, it will need to look something like this:
- Put the cluster into global maintenance mode
- Put 1 host into full maintenance mode / deactivate it
- Stop gluster
- Remove the storage
- Add the new storage & reconfigure
- Start gluster
- Re-add the host to the cluster
Adding the new storage & reconfiguring is the head scratcher for me, given
that I don't have room for the old hard drives + new hard drives at the
same time.
Sent with ProtonMail <https://protonmail.com/> Secure Email.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, July 10th, 2021 at 5:55 AM, Strahil Nikolov <
hunter86_bg(a)yahoo.com> wrote:
Hi David,
any storage operation can cause unexpected situations, so always plan your
activites for low traffic hours and test them on your test environment in
advance.
I think it's easier if you (command line):
-verify no heals are pending. Not a single one.
- set the host to maintenance over ovirt
- remove the third node from gluster volumes (remove-brick replica 2)
- umount the bricks on the third node
- recreate a smaller LV with '-i maxpct=90 size=512' and mount it with the
same options like the rest of the nodes. Usually I use
'noatime,inode64,context=system_u:object_r:glusterd_brick_t:s0'
- add this new brick (add-brick replica 3 arbiter 1) to the volume
- wait for the heals to finish
Then repeat again for each volume.
Adding the new disks should be done later.
Best Regards,
Strahil Nikolov
On Sat, Jul 10, 2021 at 3:15, David White via Users
<users(a)ovirt.org> wrote:
My current hyperconverged environment is replicating data across all 3
servers.
I'm running critically low on disk space, and need to add space.
To that end, I've ordered 8x 800GB ssd drives, and plan to put 4 drives in
1 server, and 4 drives in the other.
What's my best option for reconfiguring the hyperconverged cluster, to
change gluster storage away from Replica 3 to a Replica 2 / Arbiter model?
I'd really prefer not to have to reinstall things from scratch, but I'll
do that if I have to.
My most important requirement is that I cannot have any downtime for my
VMs (so I can only reconfigure 1 host at a time).
Sent with ProtonMail <https://protonmail.com/> Secure Email.
_______________________________________________
Users mailing list -- users(a)ovirt.org
To unsubscribe send an email to users-leave(a)ovirt.org
Privacy Statement: https://www.ovirt.org/privacy-policy.html
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https://www.ovirt.org/community/about/community-guidelines/
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4:44 p.m.
New subject: Reconfigure Gluster from Replica 3 to Arbiter 1/Replica 2
HI Jayme & Strahil,
Thank you again for your messages.
Reading https://stackoverflow.com/questions/52394849/can-i-change-gluster...,
I think I understand now what Strahil is suggesting.
It sounds to me like you're saying I can reconfigure the existing gluster volume
(don't destroy it) by changing it from a Replica 3 over to a Replica 2/Arbiter 1.
Then once I do that operation, I can THEN go in and put the two hosts into maintenance
mode one at a time to rebuild the RAID arrays, and then heal the volume on the larger
RAID.
So it would look like this:
1) Put 3rd host into maintenance mode & verify no heals are necessary
2) Make the 3rd host the arbiter
2a) remove-brick replica 2
-- if I understand correctly, this will basically just reconfigure the existing volume to
replicate between the 2 bricks, and not all 3 ... is this correct?
2b) add-brick replicat 3 arbiter 1
-- If I understand correctly, this will reconfigure the volume (again), adding the 3rd
server's storage back to the Gluster volume, but only as an arbiter node, correct?
3) Now with everything healthy, the volume is now a Replica 2 / Arbiter 1.... and I can
now stop gluster on each of the 2 servers getting the storage upgrade, rebuild the RAID on
the new storage, reboot, and let gluster heal itself before moving on to the next server.
Do I understand this process right?
Jayme's idea to use my 4th server as a temporary NFS location is not a bad idea. I
could definitely do that, "just in case" the Gluster volume got corrupted.
Unfortunately my backup server has spinning disks instead of SSD drives, but speed
wouldn't be too noticeable, and I could do it over a weekend or something.
Thanks again for your input.
Sent with ProtonMail Secure Email.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, July 10th, 2021 at 6:53 AM, Jayme <jaymef(a)gmail.com> wrote:
Just a thought but depending on resources you might be able to use
your 4th server as nfs storage and live migrate vm disks to it and off of your gluster
volumes. I’ve done this in the past when doing major maintenance on gluster volumes to err
on the side of caution.
On Sat, Jul 10, 2021 at 7:22 AM David White via Users
<users(a)ovirt.org> wrote:
> Hmm.... right as I said that, I just had a thought.
> I DO have a "backup" server in place (that I haven't even started
using yet), that currently has some empty hard drive bays.
>
> It would take some extra work, but I could use that 4th backup
server as a temporary staging ground to begin building the new Gluster configuration. Once
I have that server + 2 of my production servers rebuilt properly, I could then simply
remove and replace this "backup" server with my 3rd server in the cluster.
>
> So this effectively means that I have 2 servers that I can take
down completely at a single time to rebuild gluster, instead of just 1. I think that
simplifies things.
>
> Sent with ProtonMail Secure Email.
>
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>
> On Saturday, July 10th, 2021 at 6:14 AM, David White
<dmwhite823(a)protonmail.com> wrote:
>
> > Thank you. And yes, I agree, this needs to occur in a
maintenance window and be done very carefully. :)
> >
> > My only problem with this method is that I need to
*replace* disks in the two servers.
> > I don't have any empty hard drive bays, so will effectively need to put a
host into maintenance mode, remove the drives, and put new drives in.
> >
> > I will NOT be touching the OS drives, however, as those are
on their own separate RAID array.
> >
> > So, essentially, it will need to look something like this:
> >
> > - Put the cluster into global maintenance mode
> > - Put 1 host into full maintenance mode / deactivate it
> > - Stop gluster
> > - Remove the storage
> > - Add the new storage & reconfigure
> > - Start gluster
> > - Re-add the host to the cluster
> >
> > Adding the new storage & reconfiguring is the head
scratcher for me, given that I don't have room for the old hard drives + new hard
drives at the same time.
> >
> > Sent with ProtonMail Secure Email.
> >
> > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> >
> > On Saturday, July 10th, 2021 at 5:55 AM, Strahil Nikolov
<hunter86_bg(a)yahoo.com> wrote:
> >
> > > Hi David,
> > >
> > > any storage operation can cause unexpected situations,
so always plan your activites for low traffic hours and test them on your test environment
in advance.
> > >
> > > I think it's easier if you (command line):
> > >
> > > -verify no heals are pending. Not a single one.- set
the host to maintenance over ovirt- remove the third node from gluster volumes
(remove-brick replica 2)- umount the bricks on the third node- recreate a smaller LV with
'-i maxpct=90 size=512' and mount it with the same options like the rest of the
nodes. Usually I use
'noatime,inode64,context=system_u:object_r:glusterd_brick_t:s0'- add this new
brick (add-brick replica 3 arbiter 1) to the volume- wait for the heals to finish
> > >
> > > Then repeat again for each volume.
> > >
> > > Adding the new disks should be done later.
> > >
> > > Best Regards,Strahil Nikolov
> > >
> > > > On Sat, Jul 10, 2021 at 3:15, David White via
Users<users(a)ovirt.org> wrote:My current hyperconverged environment is replicating
data across all 3 servers.
> > > > I'm running critically low on disk space, and need to add space.
> > > >
> > > > To that end, I've ordered 8x 800GB ssd
drives, and plan to put 4 drives in 1 server, and 4 drives in the other.
> > > >
> > > > What's my best option for reconfiguring the
hyperconverged cluster, to change gluster storage away from Replica 3 to a Replica 2 /
Arbiter model?
> > > > I'd really prefer not to have to reinstall things from scratch,
but I'll do that if I have to.
> > > >
> > > > My most important requirement is that I cannot
have any downtime for my VMs (so I can only reconfigure 1 host at a time).
> > > >
> > > > Sent with ProtonMail Secure Email.
> > > >
> > > > _______________________________________________
> > > >
> > > > Users mailing list -- users(a)ovirt.org
> > > >
> > > > To unsubscribe send an email to
users-leave(a)ovirt.org
> > > >
> > > > Privacy Statement:
https://www.ovirt.org/privacy-policy.html
> > > >
> > > > oVirt Code of Conduct:
https://www.ovirt.org/community/about/community-guidelines/
> > > >
> > > > List Archives:
https://lists.ovirt.org/archives/list/users@ovirt.org/message/YHEAXRUNA2R...
>
> _______________________________________________
>
> Users mailing list -- users(a)ovirt.org
>
> To unsubscribe send an email to users-leave(a)ovirt.org
>
> Privacy Statement: https://www.ovirt.org/privacy-policy.html
>
> oVirt Code of Conduct:
https://www.ovirt.org/community/about/community-guidelines/
>
10:14 a.m.
New subject: Reconfigure Gluster from Replica 3 to Arbiter 1/Replica 2
2a) remove-brick replica 2
-- if I understand correctly, this
will basically just reconfigure the existing volume to replicate between the 2 bricks, and
not all 3 ... is this correct?
Yep, you are kicking out the 3rd node and the volume is converted to replica 2.
Most probably the command would be gluster volume remove-brick vmstore replica 2
host3:/path/to/brick force
2b) add-brick replicat 3 arbiter 1
-- If I understand correctly,
this will reconfigure the volume (again), adding the 3rd server's storage back to the
Gluster volume, but only as an arbiter node, correct?
Yes,I would prefer to create a fresh new LV.Don't forget to raise the inode count
higher,as this one will be an arbiter brick (see previous e-mail).
Once you add via gluster volume add-brick vmstore replica 3 arbiter 1
host3:/path/to/new/brick , you will have to wait for all heals to complete
3) Now with everything healthy, the volume is now a Replica 2 /
Arbiter 1.... and I can now stop gluster on each of the 2 servers getting the storage
upgrade, rebuild the RAID on the new storage, reboot, and let gluster heal itself before
moving on to the next server.
If you rebuild the raid, you are destroying the brick, so after mounting it back, you will
need to reset-brick. If it doesn't work for some reason , you can always remove-brick
replica 1 host1:/path/to/brick arbiter:/path/to/brick and readd them with add-brick
replica 3 arbiter 1.
I had some paused VMs after raid reshaping (spinning disks) during the healing but my lab
is running on workstations, so do it in the least busiest hours and possible backups
should have completed before the reconfiguration and not exactly during the healing ;)
Best Regards,
Strahil Nikolov
2:46 a.m.
New subject: Reconfigure Gluster from Replica 3 to Arbiter 1/Replica 2
Thank you.
I'm doing some more research & reading on this to make sure I understand
everything before I do this work.
You wrote:
If you rebuild the raid, you are destroying the brick, so after
mounting it back, you will need to reset-brick. If it doesn't work for some reason ,
you can always remove-brick replica 1 host1:/path/to/brick arbiter:/path/to/brick and
readd them with add-brick replica 3 arbiter 1.
Would it be safer to remove-brick replica 1 before I destroy the brick?
Also, you suggested creating a fresh logical volume on the node where I'm converting
from full replica to arbiter.
Would it not suffice to simply go in and erase all of the data?
I'm still not clear on how to force gluster to use a specific server as the arbiter
node.
Will gluster just "figure it out" if the logical volume on the arbiter is
smaller than on the other two nodes?
I'm also still a little bit unclear on why I need to specifically increase the inode
when I go to add-brick on the arbiter node. Or is that when (if?) I rebuild the Logical
Volume?
Do I need to increase the inode on the other two servers after I grow the RAID on the two
primary storage servers?
Below is an overview of the specific steps I think I need to take, in order:
Prepare:
Put cluster into global maintenance mode
Run the following commands:
# gluster volume status data inode
host 3 (Arbiter):
# gluster volume remove-brick data replica 2
host3.mgt.example.com:/gluster_bricks/data/data
# rm -rf /gluster_bricks/data/data/*
# ALTERNATIVELY... rebuild the logical volume? Is this really necessary?
# gluster volume add-brick data replica 3 arbiter 1
host3.mgt.example.com:/gluster_bricks/data/data
(Let the volumes heal completely)
host 1
# gluster volume remove-brick data replica 1
host1.mgt.example.com:/gluster_bricks/data/data
(rebuild the array & reboot the server)
# gluster volume add-brick data replica 3 arbiter 1
host1.mgt.example.com:/gluster_bricks/data/data
(Let the volumes heal completely)
host 2
# gluster volume remove-brick data replica 1
host1.mgt.example.com:/gluster_bricks/data/data
(rebuild the array & reboot the server)
# gluster volume add-brick data replica 3 arbiter 1
host1.mgt.example.com:/gluster_bricks/data/data
Sent with ProtonMail Secure Email.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Sunday, July 11th, 2021 at 3:14 AM, Strahil Nikolov via Users <users(a)ovirt.org>
wrote:
> 2a) remove-brick replica 2
-- if I understand correctly, this will basically just reconfigure
the existing volume to replicate between the 2 bricks, and not all 3 ... is this correct?
Yep, you are kicking out the 3rd node and the volume is converted to
replica 2.
Most probably the command would be gluster volume remove-brick
vmstore replica 2 host3:/path/to/brick force
> 2b) add-brick replicat 3 arbiter 1
-- If I understand correctly, this will reconfigure the volume
(again), adding the 3rd server's storage back to the Gluster volume, but only as an
arbiter node, correct?
Yes,I would prefer to create a fresh new LV.Don't forget to raise
the inode count higher,as this one will be an arbiter brick (see previous e-mail).
Once you add via gluster volume add-brick vmstore replica 3 arbiter 1
host3:/path/to/new/brick , you will have to wait for all heals to complete
> 3. Now with everything healthy, the volume is now a Replica 2 /
Arbiter 1.... and I can now stop gluster on each of the 2 servers getting the storage
upgrade, rebuild the RAID on the new storage, reboot, and let gluster heal itself before
moving on to the next server.
If you rebuild the raid, you are destroying the brick, so after
mounting it back, you will need to reset-brick. If it doesn't work for some reason ,
you can always remove-brick replica 1 host1:/path/to/brick arbiter:/path/to/brick and
readd them with add-brick replica 3 arbiter 1.
>
I had some paused VMs after raid reshaping (spinning disks) during
the healing but my lab is running on workstations, so do it in the least busiest hours and
possible backups should have completed before the reconfiguration and not exactly during
the healing ;)
Best Regards,
Strahil Nikolov
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7:42 a.m.
New subject: Reconfigure Gluster from Replica 3 to Arbiter 1/Replica 2
remove-brick replica 1 will deconfigure your Arbiter which leads to brick prep work on the
Arbiter - just more efforts.
Also, you suggested creating a fresh logical volume on the node where
I'm converting from full replica to arbiter.Would it not suffice to simply go in and
erase all of the data?
I can't catch the context properly, but keep in mind that
gluster uses extended fs attributes which means that either you have to clean them up, or
just 'mkfs xfs -i 512' the whole LV which for me is far simpler. As you will reuse
the disks in the other nodes - you most probably will use a new device.
Gluster arbiter is always the 3rd entry in the subvolume (3,6,9,etc).
By default inodes are a percentage of the free space, and on small disks (you don't
want 10TB raid for an arbiter brick, right?) the ammount of inodes will be smaller on the
arbiter brick.Example (numbers are made up):Host1 - 10TB disk - 10000 inodesHost2 - 10TB
disk - 10000 inodesArbiter - 100G disk - 100 inodes
Once you hit the Arbiter inode limit, you can't use it any more.
Reusing old bricks is not nice and will prevent you from future nightmares.Just remove the
3rd brick, add new disk on 3rd host, create it fresh , new arbiter, stop gluster. on 1
host, rebuild raid, reset-brick, heal, the other host too.
Best Regards,Strahil Nikolov
On Tue, Jul 20, 2021 at 2:48, David White via Users<users(a)ovirt.org> wrote:
Thank you.
I'm doing some more research & reading on this to make sure I understand
everything before I do this work.
You wrote:
If you rebuild the raid, you are destroying the brick, so after
mounting it back, you will need to reset-brick. If it doesn't work for some reason ,
you can always remove-brick replica 1 host1:/path/to/brick arbiter:/path/to/brick and
readd them with add-brick replica 3 arbiter 1.
Would it be safer to remove-brick replica 1 before I destroy the brick?
Also, you suggested creating a fresh logical volume on the node where I'm converting
from full replica to arbiter.
Would it not suffice to simply go in and erase all of the data?
I'm still not clear on how to force gluster to use a specific server as the arbiter
node.
Will gluster just "figure it out" if the logical volume on the arbiter is
smaller than on the other two nodes?
I'm also still a little bit unclear on why I need to specifically increase the inode
when I go to add-brick on the arbiter node. Or is that when (if?) I rebuild the Logical
Volume?
Do I need to increase the inode on the other two servers after I grow the RAID on the two
primary storage servers?
Below is an overview of the specific steps I think I need to take, in order:
Prepare:
Put cluster into global maintenance mode
Run the following commands:
# gluster volume status data inode
host 3 (Arbiter):
# gluster volume remove-brick data replica 2
host3.mgt.example.com:/gluster_bricks/data/data
# rm -rf /gluster_bricks/data/data/*
# ALTERNATIVELY... rebuild the logical volume? Is this really necessary?
# gluster volume add-brick data replica 3 arbiter 1
host3.mgt.example.com:/gluster_bricks/data/data
(Let the volumes heal completely)
host 1
# gluster volume remove-brick data replica 1
host1.mgt.example.com:/gluster_bricks/data/data
(rebuild the array & reboot the server)
# gluster volume add-brick data replica 3 arbiter 1
host1.mgt.example.com:/gluster_bricks/data/data
(Let the volumes heal completely)
host 2
# gluster volume remove-brick data replica 1
host1.mgt.example.com:/gluster_bricks/data/data
(rebuild the array & reboot the server)
# gluster volume add-brick data replica 3 arbiter 1
host1.mgt.example.com:/gluster_bricks/data/data
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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Sunday, July 11th, 2021 at 3:14 AM, Strahil Nikolov via Users <users(a)ovirt.org>
wrote:
> 2a) remove-brick replica 2
-- if I understand correctly, this will basically just reconfigure
the existing volume to replicate between the 2 bricks, and not all 3 ... is this correct?
Yep, you are kicking out the 3rd node and the volume is converted to
replica 2.
Most probably the command would be gluster volume remove-brick
vmstore replica 2 host3:/path/to/brick force
> 2b) add-brick replicat 3 arbiter 1
-- If I understand correctly, this will reconfigure the volume
(again), adding the 3rd server's storage back to the Gluster volume, but only as an
arbiter node, correct?
Yes,I would prefer to create a fresh new LV.Don't forget to raise
the inode count higher,as this one will be an arbiter brick (see previous e-mail).
Once you add via gluster volume add-brick vmstore replica 3 arbiter 1
host3:/path/to/new/brick , you will have to wait for all heals to complete
> 3. Now with everything healthy, the volume is now a Replica 2 /
Arbiter 1.... and I can now stop gluster on each of the 2 servers getting the storage
upgrade, rebuild the RAID on the new storage, reboot, and let gluster heal itself before
moving on to the next server.
If you rebuild the raid, you are destroying the brick, so after
mounting it back, you will need to reset-brick. If it doesn't work for some reason ,
you can always remove-brick replica 1 host1:/path/to/brick arbiter:/path/to/brick and
readd them with add-brick replica 3 arbiter 1.
>
I had some paused VMs after raid reshaping (spinning disks) during
the healing but my lab is running on workstations, so do it in the least busiest hours and
possible backups should have completed before the reconfiguration and not exactly during
the healing ;)
Best Regards,
Strahil Nikolov
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