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Home > Archive > Data Storage > October 2005 > Reliability of fibre channel disks vs. SCSI disks?
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Reliability of fibre channel disks vs. SCSI disks?
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| pete_usenet@yahoo.com 2005-09-27, 2:47 am |
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I've been told, but find it hard to believe,
that fibre channel disks are quite a bit more
reliable than SCSI disks.
My own limited experience with fibre channel disks
is that they fail at a similar rate to SCSI disks.
In the past I've used arrays that contain SCSI disks.
At my new job we use mostly fibre channel. They
seem to me to fail at a similar rate, but the sys
admin I work with is convinced that SCSI disks fail
more frequently given like circumstances ("all other
things being equal").
And aren't all current fibre channel disks really
SCSI disks "internally"? Can it be that the switching
between these two advanced interface types changes
the MTBF to a large extent?
Are there any storage gurus out there that would care
to share their overall experiences with respect to
fibre channel vs. SCSI disk failures / MTBF / etc.?
Thank you,
Pete
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| David A.Lethe 2005-09-27, 2:47 am |
| On 26 Sep 2005 21:16:02 -0700, pete_usenet@yahoo.com wrote:
>
>I've been told, but find it hard to believe,
>that fibre channel disks are quite a bit more
>reliable than SCSI disks.
>
>My own limited experience with fibre channel disks
>is that they fail at a similar rate to SCSI disks.
>In the past I've used arrays that contain SCSI disks.
>At my new job we use mostly fibre channel. They
>seem to me to fail at a similar rate, but the sys
>admin I work with is convinced that SCSI disks fail
>more frequently given like circumstances ("all other
>things being equal").
>
>And aren't all current fibre channel disks really
>SCSI disks "internally"? Can it be that the switching
>between these two advanced interface types changes
>the MTBF to a large extent?
>
>Are there any storage gurus out there that would care
>to share their overall experiences with respect to
>fibre channel vs. SCSI disk failures / MTBF / etc.?
>
>Thank you,
>Pete
There are high-end and low-end models of SCSI, FC, SATA, and other
disks. MTBFs, materials, warranty, thermal characteristics, and yes
interface types vary.
Therefore, SOME FC disks are more reliable than SOME SCSI disks and
vise-versa. However, since there aren't throw-away cheap FC disks
that you can pick up at your computer store for$49.95, then the
perception is that FC disks are more reliable ... if only because
there aren't any cheap FC disks flooding the marketplace.
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| In article <1127794562.437115.169650@g47g2000cwa.googlegroups.com>,
pete_usenet@yahoo.com says...
>
>
>I've been told, but find it hard to believe,
>that fibre channel disks are quite a bit more
>reliable than SCSI disks.
>
>My own limited experience with fibre channel disks
>is that they fail at a similar rate to SCSI disks.
>In the past I've used arrays that contain SCSI disks.
>At my new job we use mostly fibre channel. They
>seem to me to fail at a similar rate, but the sys
>admin I work with is convinced that SCSI disks fail
>more frequently given like circumstances ("all other
>things being equal").
>
>And aren't all current fibre channel disks really
>SCSI disks "internally"? Can it be that the switching
>between these two advanced interface types changes
>the MTBF to a large extent?
>
>Are there any storage gurus out there that would care
>to share their overall experiences with respect to
>fibre channel vs. SCSI disk failures / MTBF / etc.?
>
SCSI disks are similar to FC disks except for the interface,
which as nothing to do with the reliability
the easiest to understand proof of this is;
a. the fact that the warrantees are the same, as opposed to the
lesser warrantees that come with PATA or SATA drives
b the fact that most good storage configuration engineers will
use SCSI & FC drives in higher end requirements like database
& OLTP apps & use PATA & SATA drives for either lower end or
streaming requirements
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| Joseph Fagan 2005-10-28, 5:29 pm |
| <pete_usenet@yahoo.com> wrote in message
news:1127794562.437115.169650@g47g2000cwa.googlegroups.com...
>
> I've been told, but find it hard to believe,
> that fibre channel disks are quite a bit more
> reliable than SCSI disks.
>
> My own limited experience with fibre channel disks
> is that they fail at a similar rate to SCSI disks.
> In the past I've used arrays that contain SCSI disks.
> At my new job we use mostly fibre channel. They
> seem to me to fail at a similar rate, but the sys
> admin I work with is convinced that SCSI disks fail
> more frequently given like circumstances ("all other
> things being equal").
>
> And aren't all current fibre channel disks really
> SCSI disks "internally"? Can it be that the switching
> between these two advanced interface types changes
> the MTBF to a large extent?
>
> Are there any storage gurus out there that would care
> to share their overall experiences with respect to
> fibre channel vs. SCSI disk failures / MTBF / etc.?
>
> Thank you,
> Pete
Both FC and SCSI drives from all the vendors have the same
mechanical design set (for each vendor) and deliver the same reliability.
Both have a design lifetime of 5 years, after which failure
rate begins to increase (coming up the bathtub curve).
Warranty is a commercial response to commercial and
competitive pressures and is no indication of failure rate.
Vendors quote between 1.2M and 1.4M hours for both classes.
Joe
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| David A.Lethe 2005-10-30, 2:46 am |
| On Fri, 28 Oct 2005 13:51:22 +0000 (UTC), "Joseph Fagan"
<noemailplease@nowhere.ru> wrote:
><pete_usenet@yahoo.com> wrote in message
>news:1127794562.437115.169650@g47g2000cwa.googlegroups.com...
>
>Both FC and SCSI drives from all the vendors have the same
>mechanical design set (for each vendor) and deliver the same reliability.
>Both have a design lifetime of 5 years, after which failure
>rate begins to increase (coming up the bathtub curve).
>Warranty is a commercial response to commercial and
>competitive pressures and is no indication of failure rate.
>Vendors quote between 1.2M and 1.4M hours for both classes.
>
>Joe
>
That is an incorrect generalization. Just look at seagate's web site,
or another drive vendor site, and compare the differences in MTBF,
duty cycles, error rates, tolerance for shock/vibration/temperature
for a few disk drives.
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