New subject: raid swap question

8 Oct 1997


      On 10/08/97 09:10:10 you wrote:
...
We have "raid swap"ed almost three shelves worth of drives into 
an F330 at one time.  The AE recommended this method as
being faster than installing all the drives at config
time and building that large file system from scratch.
This worked fine, but still takes a significant amount 
of time.
I think by "at one time" you still mean one at a time
(a raid swap for each drive).
...
We later added a fourth shelf and "raid swap"ed all those
drives in at once.  The filer was only off the net for
the length of time it took to halt/connect the SCSI cable/
reboot.  A few hours later, after the raid swap completes,
all the additional disk space shows up - it does not show
up one drive at a time.
I don't quite understand this... if you added them while the
filer was down, you didn't "raid swap" anything.  And they
show up immediately, not a few hours later.  I think perhaps
you are talking about *raid add*, i.e. actually adding the
drives to the filesystem.  In that case you can add them
individually one drive at a time (and the filer would get
the space on drive at a time), or you can raid add them
all at once, in which case they'll all finish at about the
same time.
...
Some comments regarding DLT drives - I have heard that you
want to keep them "streaming" (feed with data) or the 
drive has to stop, wait for data, backup, reseek to the 
stop point, and start again.  This applies to both 4000/7000
series.  You pay a significant speed penalty for dropping
the drive out of streaming mode.  Our word from Netapp is
that for an F230, they sell the FW/DIff card and it works, but
it is not officially QA'd in the system, but soon should be.
Yes, streaming is important, but my point was I don't think
a 7000 non-streaming is going to be much slower than a 4000
streaming.  But, I could be wrong on this.  In any case, there
are *plenty* are start-stop behavior in a Netapp dump even
locally, so I don't think you can avoid it.
Bruce

Re: raid swap question