From: Steve Atkins <steve@blighty.com>
To: PostgreSQL General <pgsql-general@postgresql.org>
To: Pgsql-Performance ((E-mail)) <pgsql-performance@postgresql.org>
Subject: Re: Arguments Pro/Contra Software Raid
Date: Tue, 9 May 2006 10:52:45 -0700
Message-ID: <4F853BBA-175C-4B3E-BAF4-AA34B80DF6EF@blighty.com> (raw)
In-Reply-To: <4460BA8B.7010600@commandprompt.com>
References: <e3pmkc$12mk$1@news.hub.org>
<473FC220-A52C-4954-81E9-A14ED33164C2@blighty.com>
<4460BA8B.7010600@commandprompt.com>
On May 9, 2006, at 8:51 AM, Joshua D. Drake wrote:
("Using SATA drives is always a bit of risk, as some drives are lying
about whether they are caching or not.")
>> Don't buy those drives. That's unrelated to whether you use hardware
>> or software RAID.
>
> Sorry that is an extremely misleading statement. SATA RAID is
> perfectly acceptable if you have a hardware raid controller with a
> battery backup controller.
If the drive says it's hit the disk and it hasn't then the RAID
controller
will have flushed the data from its cache (or flagged it as correctly
written). At that point the only place the data is stored is in the non
battery backed cache on the drive itself. If something fails then you'll
have lost data.
You're not suggesting that a hardware RAID controller will protect
you against drives that lie about sync, are you?
>
> And dollar for dollar, SCSI will NOT be faster nor have the hard
> drive capacity that you will get with SATA.
Yup. That's why I use SATA RAID for all my databases.
Cheers,
Steve
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To: pgsql-performance@postgresql.org
Cc: steve@blighty.com, pgsql-general@postgresql.org
Subject: Re: Arguments Pro/Contra Software Raid
In-Reply-To: <4F853BBA-175C-4B3E-BAF4-AA34B80DF6EF@blighty.com>
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