Mailing List Archive: DRBD: Users

Antwort: Re: Hardware-recomendation needed

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Robert.Koeppl at knapp

Apr 2, 2012, 3:41 AM

Post #1 of 7 (564 views)
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Antwort: Re: Hardware-recomendation needed

The main downside of using a switch in your DRBD interlink is that you add
another component that can - and at the worst possible time will - fail.
If using a switched network use it with two network cards, two switches
and Active/passive bonding. Otherwise you have the switch as single point
of failure.
Mit freundlichen Grüßen / Best Regards

Robert Köppl

Customer Support & Projects
Teamleader IT Support

KNAPP Systemintegration GmbH
Waltenbachstraße 9
8700 Leoben, Austria
Phone: +43 3842 805-322
Fax: +43 3842 82930-500
robert.koeppl [at] knapp
www.KNAPP.com

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Felix Frank <ff [at] mpexnet>
Gesendet von: drbd-user-bounces [at] lists
02.04.2012 12:36

An
Digimer <lists [at] alteeve>
Kopie
drbd-user [at] lists
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Re: [DRBD-user] Hardware-recomendation needed

On 04/02/2012 10:09 AM, Digimer wrote:
> I'm open to being shown why I am wrong though (seriously :) ). Do you
> have any testing numbers or arguments against using a switch?

You got me. I've never made such analysis. It's more a case of "common
sense agrees with general recommendations agrees with general anxiety" ;-)

I'ts also that I'm fairly certain that if you do use a switched network
for you DRBD links, it is unlikely to be dedicated (because then it
would be almost trivial to remove the switch from this piece of your
setup). Again, I've been in situations where you cannot have a dedicated
link, and I sympathize, but it's a painful choice and I encourage
everyone to refrain from it.

I cannot comment on the sense (or lack thereof) in switching your
dedicated links. Your point appears valid.

Cheers,
Felix

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Apr 2, 2012, 9:24 AM

Post #2 of 7 (525 views)
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Re: Antwort: Re: Hardware-recomendation needed [In reply to]

On 04/02/2012 03:41 AM, Robert.Koeppl [at] knapp wrote:
>
> The main downside of using a switch in your DRBD interlink is that you
> add another component that can - and at the worst possible time will -
> fail. If using a switched network use it with two network cards, two
> switches and Active/passive bonding. Otherwise you have the switch as
> single point of failure.

Two links in Active/Passive across two switches is exactly how I do it.
I also ensure that nothing but DRBD uses those interfaces. I also do the
same for a dedicated cluster communication network.

https://alteeve.com/w/2-Node_Red_Hat_KVM_Cluster_Tutorial#Network

There are other benefits to switches; Bandwidth monitoring, cable
diagnostics, etc.

Now with all this said; I think I will try to squeeze some time to run
some benchmarks with and without switches when I return to my lab. I'd
much rather have numbers to back positions in debates like this. :)

--
Digimer
Papers and Projects: https://alteeve.com
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mail at tedyoung

Apr 2, 2012, 9:52 AM

Post #3 of 7 (525 views)
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Re: Antwort: Re: Hardware-recomendation needed [In reply to]

> There are other benefits to switches; Bandwidth monitoring, cable
diagnostics, etc.

If you do have the time, I would love to see any benchmarks you could
perform!

I had debated whether or not to use a switch between the two storage servers
for quite some time. I decided simply to factor out the switch to save room
on the switch and reduce complexity. I simply assumed that it could not
hurt performance (but not necessarily improve performance) to remove the
switches. However, we have yet to buy our hardware side have no way to
actually test that.

Ted Young

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Apr 2, 2012, 10:17 AM

Post #4 of 7 (530 views)
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Re: Antwort: Re: Hardware-recomendation needed [In reply to]

On 04/02/2012 09:52 AM, Ted Young wrote:
>> There are other benefits to switches; Bandwidth monitoring, cable
> diagnostics, etc.
>
> If you do have the time, I would love to see any benchmarks you could
> perform!
>
> I had debated whether or not to use a switch between the two storage servers
> for quite some time. I decided simply to factor out the switch to save room
> on the switch and reduce complexity. I simply assumed that it could not
> hurt performance (but not necessarily improve performance) to remove the
> switches. However, we have yet to buy our hardware side have no way to
> actually test that.
>
> Ted Young

I'm not an expert in benchmarking, but I will do my best. I am open to
suggestions on what and how to test.

--
Digimer
Papers and Projects: https://alteeve.com
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mail at tedyoung

Apr 2, 2012, 10:54 AM

Post #5 of 7 (527 views)
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Re: Antwort: Re: Hardware-recomendation needed [In reply to]

> I'm not an expert in benchmarking, but I will do my best. I am open to
suggestions on what and how to test.

Honestly, I am no expert either. I guess the best way would be to run a
disk benchmark such as Bonnie on the primary server: once with and once
without the switch. Any statistically significant difference between the
two would most likely be due to the switch.

Due to the flooding in Thailand, we were unable to procure hard drives last
month. So, I shelved my storage project until August. As such, I will not
be able to help much until the late summer (or winter depending on the
hemisphere).

Ted

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Robert.Koeppl at knapp

Apr 4, 2012, 5:15 AM

Post #6 of 7 (525 views)
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Antwort: Re: Hardware-recomendation needed [In reply to]

Regarding Throughput:
We have seen more than 700MB/s with two 10Gbit ethernet in balance-rr
bonding back to back connection, 10 Disk 136GB 15k SAS RAID 10,
LSI-Controller with 512MB Cache, BBU. scheduler: deadline, DRBD 8.3.11.
Mit freundlichen Grüßen / Best Regards

Robert Köppl

Customer Support & Projects
Teamleader IT Support

KNAPP Systemintegration GmbH
Waltenbachstraße 9
8700 Leoben, Austria
Phone: +43 3842 805-322
Fax: +43 3842 82930-500
robert.koeppl [at] knapp
www.KNAPP.com

Commercial register number: FN 138870x
Commercial register court: Leoben

The information in this e-mail (including any attachment) is confidential
and intended to be for the use of the addressee(s) only. If you have
received the e-mail by mistake, any disclosure, copy, distribution or use
of the contents of the e-mail is prohibited, and you must delete the
e-mail from your system. As e-mail can be changed electronically KNAPP
assumes no responsibility for any alteration to this e-mail or its
attachments. KNAPP has taken every reasonable precaution to ensure that
any attachment to this e-mail has been swept for virus. However, KNAPP
does not accept any liability for damage sustained as a result of such
attachment being virus infected and strongly recommend that you carry out
your own virus check before opening any attachment.

Lukas Gradl <proxmox [at] ssn>
Gesendet von: drbd-user-bounces [at] lists
04.04.2012 04:20

An
drbd-user <drbd-user [at] lists>
Kopie

Thema
Re: [DRBD-user] Hardware-recomendation needed

> Yes.
>
> I benchmarked exactly as described in that doc.

And a little addition:

I created a 3 32GB disks for a KVM-Guest on that SATA-Disk:

First on local LVM, second on DRBD using external metadata and third on
DRBD using internal metadata.

Each of that 32GB disks was partitioned to one 32GB partition and was
formatted inside the KVM-Guest (Debian Squeeze, disks connected as
virtio-device) with ext3.

The formatting took 19s for local lvm, 95s for drbd with external
metadata and 133s for drbd with internal metadata...

regards
Lukas

--
--------------------------
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Eduard-Bodem-Gasse 6
A - 6020 Innsbruck
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Apr 4, 2012, 11:58 AM

Post #7 of 7 (515 views)
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Re: Antwort: Re: Hardware-recomendation needed [In reply to]

On 04/04/2012 08:15 AM, Robert.Koeppl [at] knapp wrote:
>
> Regarding Throughput:
> We have seen more than 700MB/s with two 10Gbit ethernet in balance-rr
> bonding back to back connection, 10 Disk 136GB 15k SAS RAID 10,
> LSI-Controller with 512MB Cache, BBU. scheduler: deadline, DRBD 8.3.11.
> Mit freundlichen Grüßen / Best Regards
>
> Robert Köppl

Did you set rotational=0? May I ask what made you settle on 'deadline'?
Any other tweaks you'd care to share?

Thanks for the info!

--
Digimer
Papers and Projects: https://alteeve.com
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