Hi all!
Following my original post, I've included the answers I received...it seems
there are two sides to this issue (like everything else in life!)
Hope this helps someone down the road. Thanks to all who responded.
Best Regards,
Sheryl
>>>>>>>>>>>>>>>>>>>>>>>>>>>> Original Post <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
At 09:14 AM 7/15/96 -0400, I wrote:
>Good morning managers!
>
>We're getting ready to change over to a RAID configuration. Currently we
>have our swap space on two different drives, but just one controller. Is
>there any reason not to split the swap space over two controllers?
>
>Also, any gotchas in making the change-over are most certainly welcome!
>
>Thanks for your [always!] expert advice!
>
> Sheryl
>>>>>>>>>>>>>>>>>>>>>>>>>> Original Post Ends <<<<<<<<<<<<<<<<<<<<<<<<<<<<
==========================================================================
From: Clifford Krieger <ckrieger_at_psi.prc.com>
Subject: Re: Swap vs. controllers
To: campbell_at_lvc.edu (Sheryl A. Campbell)
Date: Mon, 15 Jul 1996 9:24:42 EDT
> We're getting ready to change over to a RAID configuration. Currently we
> have our swap space on two different drives, but just one controller. Is
> there any reason not to split the swap space over two controllers?
>
> Also, any gotchas in making the change-over are most certainly welcome!
>
I am sure there are some who are going to respond with much mroe experience
than I, but to my way of thinking...If I had the option, I would much
prefer to dedicate one controller to swap so that it doesn't have to share
a controller with data. Furthermore, since I suspect there are relativly
few concurrent requests for swap (perhaps this is much different when multi
processing) that there would be little benefit to splitting the
controllers. So, in short, I can think of no reason that you can't do it,
but I am not sure that you should.
-cliff
=============================================================================
Date: Mon, 15 Jul 1996 11:12 EST
From: KPOOTS_at_gects.ge.com( (Kent Poots \(416\)491-9318, Systems Support
_at_SYS$UPDATE:rebuild_the_kernel)
To: campbell_at_lvc.edu
Subject: RE: Swap vs. controllers
X-Vms-To: SMTP%"campbell_at_lvc.edu"
Regarding your planned switch to RAID,
I would suggest that you stay with ufs on your system drive, and maybe
keep it on your internal SCSI for the time being.
The combination of RAID + advfs got me into trouble a couple of weeks ago
(trouble = 2 corrupted disks).
As a result of this corruption, I moved our system disk back to the
internal SCSI (non-RAID) channel, and switched it back to ufs.
Also, make sure that your patch levels are up-to-date.
On the plus side, the DEC RAID controller seems to work very well.
Keep in mind that you have to size RAID sets right at the beginning
of the installation, and that adding members is a pain afterwards.
You have to re-create the entire raidset -- which means initializing !
The DEC Raid standalone configurator is pretty neat.
So is the X-Windows monitor utility.
Remember, to quote that ghost-busting movie, don't cross the beams ! ;-)
KP
=============================================================================
Date: Mon, 15 Jul 1996 09:41:21 -0700 (PDT)
From: "Anthony D'Atri" <aad_at_nwnet.net>
To: "Sheryl A. Campbell" <campbell_at_lvc.edu>
Subject: Re: Swap vs. controllers
References: <199607151314.JAA22386_at_oaunx1.ctd.ornl.GOV>
>Is there any reason not to split the swap space over two controllers?
Not at all, though I don't recommend using any sort of RAID device for
swap. The OS already interleaves it.
==============================================================================
From: <alan_at_nabeth.cxo.dec.com>
To: "Sheryl A. Campbell" <campbell_at_lvc.edu>
Subject: Re: Swap vs. controllers
Date: Mon, 15 Jul 96 11:21:03 -0600
X-Mts: smtp
re: Any reason NOT to have swap spread over two controllers.
Nope. If paging and especially swapping are a performance
bottleneck for the system, spliting the I/O across multiple
controllers may improve the performance slightly. Of course
the real fix for memory related performance problems is more
memory.
===============================================================================
Date: Mon, 15 Jul 1996 12:51:26 -0700
From: chu_at_musp0.Jpl.Nasa.Gov (Eugene Chu)
To: campbell_at_lvc.edu
Subject: Re: Swap vs. controllers
If you can put swap space across different drives on different controllers,
by all means do. Having multiple controllers increases the data bandwidth
for all data transfers, including swapping. Having them on different disks
on the same controller can decrease the access times, since two disks can
in theory be seeked simultaneously, but the data transfers still has to go
through the same channel.
One thing I would be a little cautious of, however, based on what I've
read on this list: It seemed that many people were having trouble
setting up their RAID system initially, so I'd wait until your RAID
system is stable before openning up a swap partition on it.
eyc
==============================================================================
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Received on Tue Jul 16 1996 - 16:50:54 NZST