I haven't had direct experience with the FC drives, although I have been
looking into them. I have a few comments.
First of all, not all FC LTO drives are created equal. The IBM drives
currently available are FC-AL devices, and not suitable for direct
connection to a switched fabric (FC-SW) SAN (you can add extra boxes to
give you a loop connection, but that is extra cost and complexity). The
Seagate drives when they arrive will be FC-SW drives, I don't know whether
or not they will also be suitable for FC-AL SANs. I wasn't aware that HP
were about to introduce an FC LTO drive, so I don't know what variety of
drive this will be.
Next, you mention FCP-2. How does this differ from FC-tape which I think is
a similar error correction protocol?
Thirdly, is it so bad if the tape drive shows an error as soon as it
occurs? I don't think many of the fibre/SCSI routers on the market can
support FCP-2 either, so you would be in just the same situation if you
used one of them.
On Mon, 26 Aug 2002 16:47:20 -0400, Helton, Brandon <bhelton AT HARRIS DOT COM>
wrote:
>I'm sorry if this is not directly related to a Legato problem/question,
but tape
>drive issues are of concern for all Legato admins.
>
>My company is trying to move toward Fibre Channel LTO tape drives (for
various
>jukeboxes, but mostly StorageTek L700). Without delving into the
politics, we
>are having issues with getting SUN to supply use drives that they will
support
>under our current support contract. Our SUN sales rep is siting the
following
>as to why SUN will not sell us (and support) FC LTO drives at this time.
>
>Right now IBM is the only company that sells the FC LTO drives, with plans
for
>Seagate in September, and HP in December. Sun has found a problem with the
error
>recovery mechanism and how this drive handles it. While time to market is
always
>a critical issue, it is equally imperative that we ship a product that
delivers
>on the promise of reliability and quality for our customers.
>
>There *will* be a FC LTO drive on our price list in early Q2 (October time
>frame). We will get details on part numbers, prices, and technical details
>several weeks before the announcement. As soon as I get this info I will
pass it
>along to you. I will also keep you updated on any changes as we are
notified.
>There have been references that the current FC drives only support fibre
channel
>arbitrated loop (fc-al), not fabric. This has been a concern for Harris
now that
>you are implementing switches into your SAN.
>
>Summary:
>
>The test data with the only LTO FC drive on the market today (IBM) reveals
an
>issue that our customers need to be aware of. The issue revolves around
error
>recovery, specifically:
>
>FCP-2 Error Recovery
>FCP-2 allows the drive to recover from low level errors, and test data
shows
>issues with the IBM LTO FC drive that are yet to be resolved. In short,
FCP-2
>error recovery allows the drive to resubmit the data frame instantly. If
the
>data is accepted the back up continues. If the problem remains the drive
will
>show the issue (error) as soon as it happens. Without FCP-2 error
recovery
>(which the IBM LTO FC drive struggles with), the backup will either abort
>instantly or will indicate at the end of the backup that there was a
problem.
>Note: The latest code in use on the IBM LTO FC is B22U0. Sun is working
closely
>with StorageTek and IBM to get this resolved.
>IBM: Shipping now (but with error recovery issues discussed
above)
>Seagate: Schedule to ship in October
>HP: Scheduled to ship in December
>
>Has anyone had any experience with SUN/Solaris based Legato servers with
FC LTO
>drives (the jukebox is farily irrelevant to me).
>
>Thanks,
>
>Brandon
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