From: pSeries AIX Geek (aixgeek@YAHOO.COM)
Date: Sat Sep 28 2002 - 13:42:25 EDT
1. Actually, a raw LV can be of LV type "jfs"; the
fact that it's raw just means that no file system has
been created.
2. If your app and/or DB vendor calls for raw LVs,
then they must also provide a way for you to query the
unsed space inside those raw LVs.
Abstracted further, the supplier of the LV format
method must supply all methods and operations needed
for that LV method. IBM supplies the "jfs" format for
LVs and hence supplies all of the relevant jfs
operations and tools. Anyone else advocating any
other LV format needs to do the same.
--- "Barnhart, Troy" <TBarnhart@RCRH.ORG> wrote:
> take a look at the "mklv" command - the lv's are
> created in "raw" vs. "jfs,
> etc."
> these raw files can take up considerable space but
> are not reported
> anywhere.
>
> from the IBM Doco Library:
>
----------------------------------------------------------------------------
> -------
> Defining a Raw Logical Volume for an Application:
> This procedure is used to define an area of physical
> and logical disk space
> that
> is under the direct control of an application rather
> than under control of
> the
> operating system and file system. The applications
> use character (raw) input
> and
> output rather than the block input and output of
> file systems, which require
> more
> software overhead. Bypassing the file system
> overhead enables applications
> to
> perform better. Raw logical volumes are most
> commonly used with database
> applications because of their need for high
> performance. While there is
> ordinarily
> a significant increase in performance, the actual
> amount of the increase
> depends
> on the database size and the driver provided by the
> application.
>
----------------------------------------------------------------------------
> -------
>
> now, on one of my aix boxes i had the DBA put his
> data on top of my drives
> built
> with jfs. (I know it's not a "best practice"
> always, but i built the
> filesystems
> to match physical drive size. the oracle vg's are
> dedicated, so i build
> them full.
> i'm more space-limitation-conscious w/ my rootvg,
> though.)
>
> but with a recent additional aix - the application
> vendor requires his
> oracle
> tablespaces to be datafiles on raw lv's.
>
> But how can i see the "null space"???
>
> combo of lslv and df-k ???
>
> I'm sure someone has run into trouble being able to
> know how much space you
> have
> left...
>
> troy
>
> Troy Barnhart, Sr. Systems Programmer,
> tbarnhart@rcrh.org
> Rapid City Regional Hospital,
> Rapid City, South Dakota, 57701
> ph: 605-719-8068 / fax: 605-719-4206
>
>
> -----Original Message-----
> From: Wesley Joyce [mailto:Wesley.Joyce@uvi.edu]
> Sent: Friday, September 27, 2002 11:41 AM
> To: IBM AIX Discussion List; aix-l@Princeton.EDU;
> Barnhart, Troy
> Subject: Re: actual space used.
> Importance: High
>
>
> I have posed a related question in the past. While
> browsing
> www.aixgeek.org, I found this excerpt
>
> Question: The "df" and "du" commands indicate that
> the file system is 50%
> full, but you notice that the total size of all
> files, as given by "ls" is
> greater than the size of the file system. How is
> this possible?
> Answer: These are sparse files, where the size of
> the file is larger than
> the amount of space it takes up. The file contains
> a large of "null
> blocks".
>
> If I remember correctly, Oracle reserves space in
> it's table spaces which
> make the data files. Those reservation might be
> what is called "null
> blocks". Wouldn't this help explain why the output
> of the df command and
> ls is different? Obviously this isn't a solution
> but it helps me to
> understand a little better. Maybe we should take
> this to an Oracle list?
>
> At 05:23 PM 9/24/2002, Barnhart, Troy wrote:
>
> >does anyone out there have a script or such that
> can tell how
> >much space you system has?
> >
> >such as something that can take the data from a
> "df -k" plus
> >the space occupied by the raw datafiles that oracle
> uses
> >
> >tia,
> >troy
> >
> >Troy Barnhart, Sr. Systems Programmer,
> >tbarnhart@rcrh.org
> >Rapid City Regional Hospital,
> >Rapid City, South Dakota, 57701
> >ph: 605-719-8068 / fax: 605-719-4206
> >
> >
> >
> >
> >---
> >Incoming mail is certified Virus Free.
> >Checked by AVG anti-virus system
> (http://www.grisoft.com).
> >Version: 6.0.391 / Virus Database: 222 - Release
> Date: 9/19/2002
>
>
> Wesley Joyce, Systems Administrator
> Center for Administrative Computing (CAC), IT
> University of the Virgin Islands
> #2 John Brewers Bay, St. Thomas, USVI 00802-9990
> (340) 693-1469 (voice) / (340) 693-1465 (fax)
> http://www.uvi.edu
>
> "If you can't explain it simply, than you don't know
> it well enough. -
> Unknown."
__________________________________________________
Do you Yahoo!?
New DSL Internet Access from SBC & Yahoo!
http://sbc.yahoo.com
This archive was generated by hypermail 2.1.7 : Wed Apr 09 2008 - 22:16:13 EDT