From: Mario Weilguni <mweilguni@sime.com>
To: Aidan Van Dyk <aidan@highrise.ca>
Cc: Joshua D. Drake <jd@commandprompt.com>
Cc: Scott Marlowe <scott.marlowe@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Experience with HP Smart Array P400 and SATA drives?
Date: Wed, 10 Dec 2008 17:05:06 +0100
Message-ID: <493FE8B2.9040809@sime.com> (raw)
In-Reply-To: <20081210155208.GR26596@yugib.highrise.ca>
References: <4934FE60.30702@sime.com>
<dcc563d10812051500h331ac82fp62142cf611b3a79d@mail.gmail.com>
<493E6023.3030800@sime.com>
<1228838308.13962.0.camel@jd-laptop.pragmaticzealot.org>
<20081209161750.GO26596@yugib.highrise.ca>
<493FB619.5060205@sime.com>
<20081210155208.GR26596@yugib.highrise.ca>
Aidan Van Dyk schrieb:
> * Mario Weilguni <mweilguni@sime.com> [081210 07:31]:
>
>
>> Why not? I know it's not performing as good as RAID-10, but it does not
>> waste 50% diskspace. RAID-6 is no option, because the performance is
>> even worse. And, on another system with RAID-5 + spare and SAS drives,
>> the same controller is working very well.
>>
>
> Like Scott said, it's all about trade-offs.
>
> With raid5, you get abysmal write performance, "make me not sleep at
> night" inconsistent parity issues, and a degraded mode that will a
> nightmare ...
>
> ... and as a trade-off you save a little money, and get good "read only"
> performance ...
>
> ... as long as you don't ever have a disk or system crash ...
>
> ... or can afford to rebuild if you do ...
>
> ... etc ...
>
In fact, for this system we're currently going to RAID10, I'm convinced
now. With other systems we have, RAID5 is a safe option for one reason,
the machines are clusters, so we have (sort of) RAID50 here:
Machine A/RAID5 <-- DRBD --> Machine B/RAID5
Seems reliable enough for me. But in this case, the machine will be
standalone, and so RAID5 might really not be the best choice.
However, I'm pretty sure we'll have the same problems with RAID10, the
problem seems to have to do with P400 and/or SATA drives.
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To: pgsql-performance@postgresql.org
Cc: mweilguni@sime.com, aidan@highrise.ca, jd@commandprompt.com, scott.marlowe@gmail.com
Subject: Re: Experience with HP Smart Array P400 and SATA drives?
In-Reply-To: <493FE8B2.9040809@sime.com>
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