Re: Performance difference between servers

I would expect any heavy write task to take 100% longer on a RAID 1
system. Unless you have a higher end RAID controller, the RAID 1 will
write data to one drive, and then write the same data to the second
drive. If you can test this, break the RAID 1 mirror and retry your test.

Evan.

On 11/15/2017 09:59 AM, Scott Whitney wrote:
>
> Well, you've got me stumped a bit on this. I prefer the easy ones. 😉
>
>
> The only thing I see here that is suspect is the 2 1TB spindle drives,
> but if that were the situation, you would just see server #2 as the
> outlier which is not what you're seeing.
>
>
> A few things I would check:
>
>
> 1) postgresql.conf on all 3 servers. What are the differences if any?
>
> 2) Logging on all systems from the host OS to the guest OS to pg (in
> the conf file).
>
> 3) Are these commands running local to the server or remote from
> another host?
>
> 4) Check the free RAM on the host OSes. Make sure you're not paging in
> the host. Whether the guests are idle or not, it won't matter if the
> host OS is swapping. I doubt it based on the specs you sent.
>
>
> Comparing #1 and #3 (leaving 2 out for the moment) gives you pretty
> much a 1:1 hardware comparison.
>
>
> If I read this correctly, running the same create db statement on #3
> as #1 take minimum twice the amount of time? That ain't right.
>
>
>
>
> ------------------------------------------------------------------------
> *From:* pgsql-admin-owner(at)postgresql(dot)org
> <pgsql-admin-owner(at)postgresql(dot)org> on behalf of kpi6288(at)gmail(dot)com
> <kpi6288(at)gmail(dot)com>
> *Sent:* Wednesday, November 15, 2017 11:43 AM
> *To:* pgsql-admin(at)postgresql(dot)org
> *Subject:* Re: [ADMIN] Performance difference between servers
>
> Trying as best as a can:
>
> #1 HP 8200 Elite microtower, i7-2600, 16GB RAM, 1 SSD 480 GB, 1 SSD
> 900 GB, Hyper-V 2012 R2 (not 2008 R2 as written in my original question)
>
> #2 Lenovo TS 150, E3-1245 V5, 40GB RAM, 2 SSD 850GB as RAID 1 (BIOS
> level), 2 HDDs 1TB as RAID 1 (BIOS level)
>
> #3 model unknown, E3-1270 V3, 32GB RAM, 2 SSD 480GB as RAID 1 (BIOS level)
>
> Server #1 is more a PC than a server.
>
> Server #1 runs in total 4 virtual guests. 8GB and 6 „cores“ dedicated
> to the server running PostgreSQL and 3GB to other machines which are
> almost 100% idle.
>
> Server #2 has currently on the one guets running PostgreSQL with 16GB
> RAM and 6 „cores“ dedicated.
>
> Server #3 runs 2 virtual guests. 12GB and 4 cores dedicated tot he
> guest runnning PostgreSQL. 4 GB and 3 cores decicated to another guest
> with is practically idle.
>
> Servers #2 and #3 have still plenty of free disk space while server #1
> is using approx. 70% oft he disks.
>
> Server #1 has much older SSDs than #2. Not sure about #3.
>
> *Von:* Scott Whitney [mailto:scott(at)journyx(dot)com]
> *Gesendet:* Mittwoch, 15. November 2017 18:19
> *An:* kpi6288(at)gmail(dot)com
> *Betreff:* Re: [ADMIN] Performance difference between servers
>
> Can you post the hardware host specs for #1, #2 and #3? If those ARE
> the hardware specs (for example, you list SSDs), can you list the
> resources assigned to the guests?
>
> ------------------------------------------------------------------------
>
> *From:*kpi6288(at)gmail(dot)com <mailto:kpi6288(at)gmail(dot)com> <kpi6288(at)gmail(dot)com
> <mailto:kpi6288(at)gmail(dot)com>>
> *Sent:* Wednesday, November 15, 2017 11:15 AM
> *To:* Scott Whitney
> *Subject:* AW: [ADMIN] Performance difference between servers
>
> Yes, exactly:
>
> Three different (hardware) machines, each having a hyper-V host and
> the Windows Servers as Hyper-V guests.
>
> *Von:*Scott Whitney [mailto:scott(at)journyx(dot)com]
> *Gesendet:* Mittwoch, 15. November 2017 18:11
> *An:* kpi6288(at)gmail(dot)com <mailto:kpi6288(at)gmail(dot)com>;
> pgsql-admin(at)postgresql(dot)org <mailto:pgsql-admin(at)postgresql(dot)org>
> *Betreff:* Re: [ADMIN] Performance difference between servers
>
> Are you saying that each of these servers is a virtual HyperV machine
> running under a hardware host?
>
> ------------------------------------------------------------------------
>
> *From:*pgsql-admin-owner(at)postgresql(dot)org
> <mailto:pgsql-admin-owner(at)postgresql(dot)org>
> <pgsql-admin-owner(at)postgresql(dot)org
> <mailto:pgsql-admin-owner(at)postgresql(dot)org>> on behalf of
> kpi6288(at)gmail(dot)com <mailto:kpi6288(at)gmail(dot)com> <kpi6288(at)gmail(dot)com
> <mailto:kpi6288(at)gmail(dot)com>>
> *Sent:* Wednesday, November 15, 2017 11:06 AM
> *To:* pgsql-admin(at)postgresql(dot)org <mailto:pgsql-admin(at)postgresql(dot)org>
> *Subject:* [ADMIN] Performance difference between servers
>
> We have 3 different servers, one (the oldest) ist significantly faster
> at certain operations and I can’t find out the reason:
>
> (table created in monospace font)
>
> Server Processor  RAM   CrystalDiskMark   pgbench   CREATE DATABASE   OS
>
>   #1  i7-2600   8GB     495 / 473      26.000      4.5 … 6 s      W/
> Server 2008 R2 on Hyper V Server 2008
>
>    #2 E3-1245   16GB    797 / 514     50.000      13 … 19 s      W/
> Server 2016 Std. on Hyper V Server 2016
>
>  #3    E3-1270   12GB    933 / 334        40.000      13 … 20 s W/
> Server 2008 Essentials on Hyper V Server 2016
>
> CrystalDiskMark: „Seq Q32T1“
>
> Pgbench:
>
>    pgbench -i -s 200 -U postgres pgbench
>
> pgbench -c 40 -j 10 -T 150 -U postgres -S -P 5 pgbench
>
> CREATE DATABASE:
>
>    create database test with template myTemplate
>
> All running PostgreSQL 9.6 x64 with similar configuration. All running
> as virtual machines, no other virtual machines creating any load.
> Using the same template database on all machines.
>
> Although the indicative numbers of pgbench and CrystalDiskMark show
> better values for server #2 and #3, server #1 creates a new database
> considerably faster.
>
> All servers have SSDs. Server #1 has two single SSDs (a system disk
> and a data disk). Servers #2 and #3 have only one logical disk for
> system and data, and this is two SSDs running as RAID 1. This may be
> slower but if it is, I would excpect this also to show up in the
> pgbench results.
>
> The reason behind this exercise is that a test application was also
> reported to be slower on server #2 and 3.
>
> Any idea how to track down the performance difference?
>
> Thank you
>
> Klaus
>
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>
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