From: Geoff Tolley <geoff@polimetrix.com>
To: david@lang.hm
Cc: Ron <rjpeace@earthlink.net>
Cc: jason@ohloh.net <jason@ohloh.net>
Cc: pgsql-performance@postgresql.org
Subject: Re: SCSI vs SATA
Date: Wed, 04 Apr 2007 11:03:23 -0700
Message-ID: <4613E86B.2080704@polimetrix.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0704032106210.30746@asgard.lang.hm>
References: <9C0858F5-0A48-4AF9-80FF-E4BA14F0F965@ohloh.net>
<E1HYs6Y-0008O5-SN@elasmtp-banded.atl.sa.earthlink.net>
<E1HYsBX-0006ZE-JG@elasmtp-banded.atl.sa.earthlink.net>
<4613053F.5070401@polimetrix.com>
<Pine.LNX.4.64.0704032106210.30746@asgard.lang.hm>
david@lang.hm wrote:
> for that matter, with 20ish 320G drives, how large would a parition be
> that only used the outer pysical track of each drive? (almost certinly
> multiple logical tracks) if you took the time to set this up you could
> eliminate seeking entirely (at the cost of not useing your capacity, but
> since you are considering a 12x range in capacity, it's obviously not
> your primary concern)
Good point: if 8x73GB in a RAID10 is an option, the database can't be
larger than 292GB, or 1/12 the available space on the 320GB SATA version.
> note that the CMU and Google studies both commented on being surprised
> at the lack of difference between the reliability of SCSI and SATA drives.
I'd read about the Google study's conclusions on the failure rate over time
of drives; I hadn't gotten wind before of it comparing SCSI to SATA drives.
I do wonder what their access patterns are like, and how that pertains to
failure rates. I'd like to think that with smaller seeks (like in the
many-big-SATAs-option) the life of the drives would be longer.
Oh, one big advantage of SATA over SCSI: simple cabling and no need for
termination. Although SAS levels that particular playing field.
Cheers,
Geoff
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To: pgsql-performance@postgresql.org
Cc: geoff@polimetrix.com, david@lang.hm, rjpeace@earthlink.net, jason@ohloh.net
Subject: Re: SCSI vs SATA
In-Reply-To: <4613E86B.2080704@polimetrix.com>
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