New subject: Defraging the excahgne DB

7 Jun 2004


      If you use Waffle scan then this defrags the entire vol right? And if so is
it safe to use on your exchange DB? If it is then that would be greate
-----Original Message-----
From: avarni@tech.cj.com [mailto:avarni@tech.cj.com] 
Sent: Monday, June 07, 2004 10:19 AM
To: Waters, G Scott THE LOG.SEC TEAM
Cc: SKIP HOFMANN; 'Borders, Rich'; toasters@mathworks.com
Subject: RE: Defraging the excahgne DB
At least on 6.3.2 -- I've noticed that WAFL SCAN REALLOCATE will
'pause' indefinately IFF you're over your snapshot reserve.  Otherwise
I've run this many times with no problems.  Make sure you aren't
over your snapshot reserve and your scan should 'continue'.
On Mon, 7 Jun 2004, Waters, G Scott THE LOG.SEC TEAM wrote:
] 
] WOW ... this is the exact opposite of what NetApp support told me.
] 
] On a volume used for storing Exchange data, the WAFL SCAN REALLOCATE
command
] will never complete.  It goes for a while and then stalls.
] 
] We monitor the layout ratios weekly and schedule down time to perform an
] offline DEFRAG every 4 - 6 weeks.
] 
] This is all based on information received at the time ... If NetApp has
] fixed this then someone enlighten me.
] 
] 
] - Scott W.
] 
] 
] -----Original Message-----
] From: SKIP HOFMANN [mailto:SKIP.HOFMANN@ttisg.com] 
] Sent: Thursday, June 03, 2004 2:31 PM
] To: 'Borders, Rich'; toasters@mathworks.com
] Subject: RE: Defraging the excahgne DB
] 
] 
] Hi 
] 
] I just got done talking with support at Netapp, and they told me that
doing
] an offline defrag of my exchange DB using the esutil will have absolutely
no
] impact on the exchange DB on the filer, and they also told me that in
order
] to defrag the exchange DB I must use the fillers Waffle utility to do this
] and that this would also defragment everything on the vol. They said that
] it's the responsibility of the file system on the filer to determine if a
] vol is fragmented or not, this includes all data on the vol. So knowing
this
] is it safe to defrag a vol that contains an exchange DB??
] 
] Thanks again for your help it is much appreciated
] 
] Skip
] 
] -----Original Message-----
] From: Borders, Rich [mailto:Rich.Borders@netapp.com] 
] Sent: Thursday, June 03, 2004 11:13 AM
] To: SKIP HOFMANN; toasters@mathworks.com
] Subject: RE: Defraging the excahgne DB
] 
] <<< I am replying in-line >>> 
]  
] 
] 	From: SKIP HOFMANN [mailto:SKIP.HOFMANN@ttisg.com] 
] 	Sent: Thursday, June 03, 2004 1:33 PM
] 	To: toasters@mathworks.com
] 	Subject: Defraging the excahgne DB
] 	
] 	
] 
] 	Howdy
] 
] 	 
] 
] 	I have my exchange 5.5 DB pub and priv and my filler it's a
] FAS250 and I want to know a few things
] 
] 	 
] 
] 	#1 can I run the eseutil utility if the DB is on my FAS 250 to
] defrag the DB?
] 
] 
] 
] 
] 
] <<< This is doable as it is an offline defrag. The curious thing about
] doing this is that you are accomplishing the APPLICATION defrag, and at
] the same time getting a great by-product of a WAFL defrag. ( Essentially
] a database re-write ) >>>
] 
] 
] 
] 
] 
] 	 
] 
] 	#2 is it the filer that determines if the exchange DB is
] fragmented or not, and if it is how would I defrag the DB?
] 
] 	 
] 
] <<<The Application can fragment ( very common and accounted for by an
] online and offline defrag funciton in Exchange ) and the Filer can
] fragment. I say that tounge in cheek because the fragmentation is really
] only identified when you access the data. Since the database is one
] large file the request for data in it is atypical, the data 'fragments'
] over time. The blocks of the filer rarely match up to the blocks of the
] database, so the issues becomes when you want to get a LOT of sequential
] data from a large file ( aka mail store verify ) you will be essentially
] asking the filer to scan through it's blocks at a super high rate of
] speed.>>>
] 
] 
] 
] 
] 
] 	#3 what happens to all other data that is stored on the same vol
] as the exchange DB once I defrag this vol? ie snap shots 
] 
] 
] <<<The Mail store can be reallocated or the volume can. I would
] recommend the snapshots be removed as you can really get yourself into a
] pickle by 'RE'-writing a database with an application defrag, or a WAFL
] reallocate. If you are short on space, you need to get the snapshots out
] of there. Snapshots are locked images and if the file system is
] 'fragmented' then it is unlikely that you are doing much more than
] spinning your wheels if you are trying to defragment into a fragemnted
] snapshot. >>>
] 
] 	 
] 
] 	#4 I ran a waffle scan and I got a reading of 1.8 si this
] fragmented?
] 
] 
] That is basically a ratio of actual file size ( df essentially ) to
] block allocation. Ex. A one terabyte volume has a 500 gig database. If
] it's layout is 1 then the File is essentially using the exact number of
] blocks that a Filer of 500 gigs needs. If the layout were 1.8 then the
] 500 gig df would still be 500 but the block allocation would actually be
] closer to the 900 gig . This is usually not an issue until the ratio
] takes the block allocation higher then the volume size. A 2.1 layout
] would mean that a 500 gig df would be 1.05 TB. This means you are
] rescanning on a request of data on the last .05 TB. If the Filer were a
] 900 gig df, then a layout of 1.8 would be MUCH more impactful. It is not
] the end of the world, you just have to manage it. You are on the right
] track I can see, so good luck.
] 
] 
] 
] 	Thanks a bunch
] 
] 	 
] 
] 	Skip
] 
] Rich Borders
]