From: | Geoff Tolley <geoff(at)polimetrix(dot)com> |
---|---|
To: | david(at)lang(dot)hm |
Cc: | Ron <rjpeace(at)earthlink(dot)net>, "jason(at)ohloh(dot)net" <jason(at)ohloh(dot)net>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: SCSI vs SATA |
Date: | 2007-04-04 18:03:23 |
Message-ID: | 4613E86B.2080704@polimetrix.com |
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Lists: | pgsql-performance |
david(at)lang(dot)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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