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Today's Topics:
1. Re: Postgres optimised h/w (Martin Moore)
2. Re: Postgres optimised h/w (Steve King)
3. Re: Postgres optimised h/w (Amias Channer)
4. LPD 2017.1 date and general interest? (Sebastian)
5. Swapfile by default instead of partiton for... (Sebastian)
----------------------------------------------------------------------
Message: 1
Date: Fri, 16 Dec 2016 17:05:20 +0000
From: Martin Moore <martinm@it-helps.co.uk>
To: Martin <inkubus@interalpha.co.uk>, Bristol and Bath Linux User
Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Postgres optimised h/w
Message-ID: <D66FD56B-4FE0-416B-A92F-8FA8F0E1EFB3@it-helps.co.uk>
Content-Type: text/plain; charset="UTF-8"
I have to say that in my decades of experience, adding h/w such as raid controllers, multiple psu sharing boards etc. usually results in the resilience bit failing! I've lost systems due to failed raid controllers and power sharing boards more than failed drives and PSUs!
I've also heard that h/w RAID controllers use their own format which renders them useless without the controller.
On 16/12/2016, 16:36, "Bristol on behalf of Martin via Bristol" <bristol-bounces@mailman.lug.org.uk on behalf of bristol@mailman.lug.org.uk> wrote:
On Fri, 2016-12-16 at 16:26 +0000, Steve King via Bristol wrote:
> >
> > I would also recommend a hardware RAID controller for a database: MD
> > RAID is great but far less flexible, and the more processing and IO you
> > can farm off to dedicated hardware the faster your database server will
> > go.
> >
>
> In what way is MDRAID less flexible than hardware raid?
> I have never found hardware raid offers more performance or more
> flexibility, plus you are at the mercy of the hardware vendor if you hit a
> problem.
^^^^^^^^^^^^^ THISTHISTHIS! What he said!
I have recovered RAID systems (personally and advised people in doing
so) that were theoretically broken past the point of repair. This
required reading the kernel source but we got all of the data back. I
have seen systems built on hardware RAID with a fraction of the problems
leading to complete data loss because the vendor wouldn't even bother
answering questions unless you were bringing them millions in revenue.
Unless you REALLY REALLY need the extra performance (and are sure that
you get it) I'd suggest software RAID.
That said, don't most of the big database servers have a "work directly
from the partitions and balance data as you see fit" mode? Because for
them filesystems are just overhead.
Cheers,
- Martin
_______________________________________________
Bristol mailing list
Bristol@mailman.lug.org.uk
https://mailman.lug.org.uk/mailman/listinfo/bristol
------------------------------
Message: 2
Date: Fri, 16 Dec 2016 17:13:09 -0000
From: "Steve King" <debian@invux.com>
To: "Bristol and Bath Linux User Group" <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Postgres optimised h/w
Message-ID:
<19e91788bc3cc775d62da0a77c4c5bb4.squirrel@dazzle.invux.com>
Content-Type: text/plain;charset=iso-8859-1
> A hardware raid removes the overhead from the kernel, has RAM to cache to
> on the controller and has a battery for power failure redundancy.
> It's all down to which raid card you have and what the underlying system
> is.
> An i7 may outperform an i386 with a perc5/I.
> It all depends on what you have available, what your budget is and what
> you
> would like to do with it.
> For example I would be hard pushed to run my 10x3TB RAID6 in kernel.
> ZFS does look really promising in anD raid but I have not ventured that
> far
> yet.
>
But your use case is for a filesystem vastly bigger than the amount of RAM
available. In that case, yes a hardware card may offer slightly better
performance, but you all the fun of dealing with drivers which have many
fewer customers than the basic SAS/SATA chips built into most xeon
chipsets. Anything current in the last 10 years will use DMA and have
dedicated silicon in the chipset or processor for SAS/SATA, so kernel
overhead is minimal.
Plus you have to replace Cache RAM batteries.
In this case OP is talking about a database that fits into a few hundred
pounds worth of RAM, low on writes. Ideally the whole database will sit in
RAM and only the occasional updates will be pushed to SSD.
I would recommend ECC RAM though.
--
Steve
------------------------------
Message: 3
Date: Fri, 16 Dec 2016 17:25:55 +0000
From: Amias Channer <me@amias.net>
To: Martin Moore <martinm@it-helps.co.uk>, Bristol and Bath Linux
User Group <bristol@mailman.lug.org.uk>
Cc: Martin <inkubus@interalpha.co.uk>
Subject: Re: [bristol] Postgres optimised h/w
Message-ID:
<CAMgU7XUszaV3rwbZs0bpA_tke7yep4QTiCvJdSi-ixEGLWafHA@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Hello Luggers,
I would definitely agree that software raid is as good as hardware
raid unless you are a mega corporation, in which case just do it all
in live RAM anyway. The complexity and proprietary formats make them
dangerous. Server bioses don't need any more reasons to boot up slowly
which is usually the case with hardware raid.
Server storage is IMHO really about concurrent access and RAID helped
improve that on hard disks but its pretty much pointless on SSD/NVMe
solutions where nothing is spinning and an individual drive can
saturate the controller. Mirroring in this context is useful but
really only to slower storage like HDD.
+1 on the ECC ram , it should be standard on anything more than 16GB.
Cheers
Amias
On 16 December 2016 at 17:05, Martin Moore via Bristol
<bristol@mailman.lug.org.uk> wrote:
> I have to say that in my decades of experience, adding h/w such as raid controllers, multiple psu sharing boards etc. usually results in the resilience bit failing! I've lost systems due to failed raid controllers and power sharing boards more than failed drives and PSUs!
>
> I've also heard that h/w RAID controllers use their own format which renders them useless without the controller.
>
>
>
>
> On 16/12/2016, 16:36, "Bristol on behalf of Martin via Bristol" <bristol-bounces@mailman.lug.org.uk on behalf of bristol@mailman.lug.org.uk> wrote:
>
> On Fri, 2016-12-16 at 16:26 +0000, Steve King via Bristol wrote:
> > >
> > > I would also recommend a hardware RAID controller for a database: MD
> > > RAID is great but far less flexible, and the more processing and IO you
> > > can farm off to dedicated hardware the faster your database server will
> > > go.
> > >
> >
> > In what way is MDRAID less flexible than hardware raid?
> > I have never found hardware raid offers more performance or more
> > flexibility, plus you are at the mercy of the hardware vendor if you hit a
> > problem.
> ^^^^^^^^^^^^^ THISTHISTHIS! What he said!
>
> I have recovered RAID systems (personally and advised people in doing
> so) that were theoretically broken past the point of repair. This
> required reading the kernel source but we got all of the data back. I
> have seen systems built on hardware RAID with a fraction of the problems
> leading to complete data loss because the vendor wouldn't even bother
> answering questions unless you were bringing them millions in revenue.
>
> Unless you REALLY REALLY need the extra performance (and are sure that
> you get it) I'd suggest software RAID.
>
> That said, don't most of the big database servers have a "work directly
> from the partitions and balance data as you see fit" mode? Because for
> them filesystems are just overhead.
>
> Cheers,
> - Martin
>
>
>
> _______________________________________________
> Bristol mailing list
> Bristol@mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/bristol
>
>
>
> _______________________________________________
> Bristol mailing list
> Bristol@mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/bristol
------------------------------
Message: 4
Date: Fri, 16 Dec 2016 18:02:47 +0000
From: Sebastian <sebsebseb_mageia@gmx.com>
To: <bristol@mailman.lug.org.uk>, <sebsebseb_mageia@gmx.com>
Subject: [bristol] LPD 2017.1 date and general interest?
Message-ID: <9343f7c6-bf2a-40e3-bfee-ac5baf8b3bd9@gmx.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Hi
As has been mentioned to this mailing list before etc, the plan is to have
another two Linux Presentation Day ( http://linux-presentation-day.org.uk
http://linux-presentation-day.org ) events next year 2017 in Bristol. I
have also been thinking generally here and there on cerrtain days not just
today, about which date the event should be on, and also who would
generally be interested in helping with it and in what kind of ways. Yes a
LUG meeting is tommorow, and yes its one of those things that could be
talked about there, but I would like to start at least a bit of a
discussion about this now on the mailing list, hence this email message.
For the next LPDs no set dates, unlike before with everyone ( or mostly
everyone) having one on the same day, however Germany will be having one in
early May on Saturday 6th. I think meant to really try and have one by
country though, everyone in the country on the same day, however so far
only Blackpool and Hereford have had them in the past as well, when it
comes to the UK. I think really the date can be pretty much any date. I
also got a email before from the main organiser that also mentioned how
certain other counteries outside Europe should be be having them as well
next time such as the USA. It was also interesting reading about how those
events went in Germany in that email, for exmpler flyers and posters didn't
seem to go that well with the public, or Berln LUG as in LPD itself, Google
advertising that they did. For our one most people came in from the about
two weeks of paid Facebook adveritinsg it seems. Also got a nice email from
someone else how their one went in their country last time.
I had mentioned on Facebook before about the next LPD being in, or probably
being in April, and I think it should be in April on a Saturday. A
Saturday after the Ubuntu 17.04 release on Thursday April 13th, and after
that weeks weekend which is Easter weekend. If we want to target some
younger people as well or familes then it may be worth aligning the event
with the school Easter holidays and marketing it properly to such an
audiance some how as well, but if not, then that doesn't really matter.
Plus I remember seeing two seemingly younger people walking out last time.
I also think that help with installs should be encouraged to be done at
LUG meetings or somewhere else, so that people move around the event areas
properly. Which didn't seem to happen enough last time, for example I
didn't see anyone actually sitting there watching Creative Commons open
movies, or watching Creative Commons graphics slide show. I still think
that the idea of combineing it with a Creative Commons showcase to make
things more interesting, is a great idea of mine, still though.
Its definetly won't be for everyones Linux distros taste, but like it or
not, certain interesting seeable by the user, things are going on now with
Ubuntu, and Ubuntu 17.04 will have more of that. Yes it's not long term
support, but for the just mentioned kind of reasons may be worth showing
that properly with Unity 8 etc on lap tops at the next LPD. With some
other interfaces and distros as well, and of course with some mobile Linux
as well, like we just did. That is a main reason right there why I would
like the LPD event to be after the release. The following weekend after
the Easter weekend of that week, would be the usual LUG meeting anyway,
but maybe next time round we should actually have that at the pub as usual
as well, and then do the event the following weekend of Saturday 29th
April? Event organisers should ideally meet at least a week before the
event, so why not at the standard LUG meeting then?
The weekend after the LUG meeting is the bank holiday weekend it seems,
but not that many people go away in that early one I assume in general
anyway, with people being more liekly to go away around Easter time it
seems. So yes Saturday April 29th 2017 should be the better date I guess,
or Saturday 22nd 2017 instead, the LUG meeting date.
As for times of the event and venue, I am thinking 1pm to 6pm for the
public, with mid day to 1pm booked for helpers, and 6pm to 7pm booked as
well for clearing up and possibly eating down there or running over,
similar to last time. Down there being the same place as before in that
context, however with enough good enough reasons might go for another venue
instead next time.
I know about certain people who would like to help with the event, one or
two to help organise it seems even, but would be good if people could
confirm that more now here on the list, and in what kind of ways would like
to help and why. Also who would genearally help us market/promote the
event and spread interest?
Best Regards
Sebastian
P.S
Little email client to name issue now when sending to the list, same for
the previous LUG meeting email. Not sure if anyone else will see that
though.
--
Sent using Dekko from my Ubuntu device
------------------------------
Message: 5
Date: Fri, 16 Dec 2016 19:32:53 +0000
From: Sebastian <sebsebseb_mageia@gmx.com>
To: <bristol@mailman.lug.org.uk>, <sebsebseb_mageia@gmx.com>
Subject: [bristol] Swapfile by default instead of partiton for...
Message-ID: <4dedee82-b4b2-461a-ae48-0315e21332c9@gmx.com>
Content-Type: text/plain; charset=utf-8; format=flowed
HI
Been some intereresting news today, Ubuntu news, that for Ubuntu 17.04
will be a swapfile by default instead of a partition. Not quite sure how
wthat would work with multiple distros if stored inside Ubuntu. Also
looking at where I found out again, some comments saying how that woudn't
really work with BTFS it seems. Anyway wanted to share here for some
general comments to do with that, (and actually doing so now, was going to
maybe earlier on it's own or later on in another email),
http://www.omgubuntu.co.uk/2016/12/ubuntu-17-04-drops-swaps-swap-partitions-swap-files
Regards
Sebastian
--
Sent using Dekko from my Ubuntu device
------------------------------
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------------------------------
End of Bristol Digest, Vol 673, Issue 8
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