O/S read block size.

Need to set few Oracle parameters based on solaris read buffer size.
Experts out there can any one pass on the links and or documents as well how to check in the system?
Knowing this would enable me to tune the system and improve the system I/O.
My env is Solaris v5.10 ~ 64 bit system .

I thought some one would give their valuable points!!!!!
I could read it as 64KB in some documents?
Is that right?
Can this be configured?

Similar Messages

Mac Pro RAID block size recommendations for working with audio in Logic Pro

I have recently ordered a Mac Pro and plan to do a RAID configuration across 3 HDD's
The RAID type i am going to do is a RAID 0 striped.
The computer is going to be used primarily for audio post production and working with 20+ 24-Bit audio files at any one time within a Logic project.
I want to know what is the best block size i should use when configuring the RAID.
I understand that using a higher block size is best for working with large files but do i need to do this in my case or will the default 32k block size be enough?
Thanks in advance

Use 64k. Things like databases like having 32k blocks because of all the small files. Audio files are pretty small even at 24-bit 192KHz. Go to 128k if all you are doing is streaming and no samples. But 20+ 24-bit is really not too large anyway considering most modern HDD's can stream 100MB/s off one spindle. You'll probably be fine regardless of the block size you choose. But most audio pro's choose 64k.

ORA-00349: failure obtaining block size for '+Z' in Oracle XE

Hello,
I am attempting to move the online redo log files to a new flash recovery area location created on network drive "Z" ( Oracle Database 10g Express Edition Release 10.2.0.1.0).
When I run @?/sqlplus/admin/movelogs; in SQL*Plus as a local sysdba, I get the following errors:
ERROR at line 1:
ORA-00349: failure obtaining block size for '+Z'
ORA-06512: at line 14
Please let me know how to go about resolving this issue.
Thank you.
See below for detail:
Connected.
SQL> @?/sqlplus/admin/movelogs;
SQL> Rem
SQL> Rem $Header: movelogs.sql 19-jan-2006.00:23:11 banand Exp $
SQL> Rem
SQL> Rem movelogs.sql
SQL> Rem
SQL> Rem Copyright (c) 2006, Oracle. All rights reserved.
SQL> Rem
SQL> Rem NAME
SQL> Rem movelogs.sql - move online logs to new Flash Recovery Area
SQL> Rem
SQL> Rem DESCRIPTION
SQL> Rem This script can be used to move online logs from old online
log
SQL> Rem location to Flash Recovery Area. It assumes that the database
SQL> Rem instance is started with new Flash Recovery Area location.
SQL> Rem
SQL> Rem NOTES
SQL> Rem For use to rename online logs after moving Flash Recovery
Area.
SQL> Rem The script can be executed using following command
SQL> Rem sqlplus '/ as sysdba' @movelogs.sql
SQL> Rem
SQL> Rem MODIFIED (MM/DD/YY)
SQL> Rem banand 01/19/06 - Created
SQL> Rem
SQL>
SQL> SET ECHO ON
SQL> SET FEEDBACK 1
SQL> SET NUMWIDTH 10
SQL> SET LINESIZE 80
SQL> SET TRIMSPOOL ON
SQL> SET TAB OFF
SQL> SET PAGESIZE 100
SQL> declare
2 cursor rlc is
3 select group# grp, thread# thr, bytes/1024 bytes_k
4 from v$log
5 order by 1;
6 stmt varchar2(2048);
7 swtstmt varchar2(1024) := 'alter system switch logfile';
8 ckpstmt varchar2(1024) := 'alter system checkpoint global';
9 begin
10 for rlcRec in rlc loop
11 stmt := 'alter database add logfile thread ' ||
12 rlcRec.thr || ' size ' ||
13 rlcRec.bytes_k || 'K';
14 execute immediate stmt;
15 begin
16 stmt := 'alter database drop logfile group ' || rlcRec.grp;
17 execute immediate stmt;
18 exception
19 when others then
20 execute immediate swtstmt;
21 execute immediate ckpstmt;
22 execute immediate stmt;
23 end;
24 execute immediate swtstmt;
25 end loop;
26 end;
27 /
declare
ERROR at line 1:
ORA-00349: failure obtaining block size for '+Z'
ORA-06512: at line 14
Can someone point me in the right direction as to what I may be doing wrong here - Thank you!

888442 wrote:
I am trying to drop and recreate ONLINE redo logs on my STANDB DATABASE (11.1.0.7)., but i am getting the below error.
On primary, we have done the changes., ie we added new logfile with bigger size and 3 members. When trying to do the same on Standby we are getting this error.
Our database is in Active DG Read only mode and the oracle version is 11.1.0.7.
I have deffered the log apply and cancelled the managed recovery, and dg is in manual mode.
SQL> alter database Add LOGFILE GROUP 4 ('+DT_DG1','+DT_DG2','+DT_DG3') SIZE 1024M;
alter database Add LOGFILE GROUP 4 ('+DT_DG1','+DT_DG2','+DT_DG3') SIZE 1024M
ERROR at line 1:
ORA-00349: failure obtaining block size for '+DT_DG1'First why you are dropping & recreating online redo log files on standby.
On standby only standby redo log files will be used. Not sure what you are trying to do.
here is example how to create online redo log files, Check that diskgroup is mounted and have sufficient space to create.
sys@ORCL> select member from v$logfile;
MEMBER
C:\ORACLE\ORADATA\ORCL\REDO03.LOG
C:\ORACLE\ORADATA\ORCL\REDO02.LOG
C:\ORACLE\ORADATA\ORCL\REDO01.LOG
sys@ORCL> alter database add logfile group 4 (
2     'C:\ORACLE\ORADATA\ORCL\redo_g01a.log',
3     'C:\ORACLE\ORADATA\ORCL\redo_g01b.log',
4     'C:\ORACLE\ORADATA\ORCL\redo_g01c.log') size 10m;
Database altered.
sys@ORCL> select member from v$logfile;
MEMBER
C:\ORACLE\ORADATA\ORCL\REDO03.LOG
C:\ORACLE\ORADATA\ORCL\REDO02.LOG
C:\ORACLE\ORADATA\ORCL\REDO01.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01A.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01B.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01C.LOG
6 rows selected.
sys@ORCL>
Your profile:-
888442
     Newbie
Handle:      888442
Status Level:      Newbie
Registered:      Sep 29, 2011
Total Posts:      12
Total Questions:      8 (7 unresolved)
Close the threads if answered, Keep the forum clean.

Tablespaces and block size in Data Warehouse

We are preparing to implement Data Warehouse on Oracle 11g R2 and currently I am trying to set up some storage strategy - unfortunately I have very little experience with that. The question is what are general advices in such considerations according table spaces and block size? I made some research and it is hard to find some clear answer, there are resources advising that block size is not important and can be left small (8 KB), others state that it is crucial and should be the biggest possible (64KB). The other thing is what part of data should be placed where? Many resources state that keeping indexes apart from its data is a myth and a bad practice as it may lead to decrease of performance, others say that although there is no performance benefit, index table spaces do not need to be backed up and thats why it should be split. The next idea is to have separate table spaces for big tables, small tables, tables accessed frequently and infrequently. How should I organize partitions in terms of table spaces? Is it a good idea to have "old" data (read only) partitions on separate table spaces?
Any help highly appreciated and thank you in advance.

Wojtus-J wrote:
We are preparing to implement Data Warehouse on Oracle 11g R2 and currently I am trying to set up some storage strategy - unfortunately I have very little experience with that. With little experience, the key feature is to avoid big mistakes - don't try to get too clever.
The question is what are general advices in such considerations according table spaces and block size? If you need to ask about block sizes, use the default (i.e. 8KB).
I made some research and it is hard to find some clear answer, But if you get contradictory advice from this forum, how would you decide which bits to follow ?
A couple of sensible guidelines when researching on the internet - look for material that is datestamped with recent dates (last couple of years), or references recent - or at least relevant - versions of Oracle. Give preference to material that explains WHY an idea might be relevant, give greater preference to material that DEMONSTRATES why an idea might be relevant. Check that any explanations and demonstrations are relevant to your planned setup.
The other thing is what part of data should be placed where? Many resources state that keeping indexes apart from its data is a myth and a bad practice as it may lead to decrease of performance, others say that although there is no performance benefit, index table spaces do not need to be backed up and thats why it should be split. The next idea is to have separate table spaces for big tables, small tables, tables accessed frequently and infrequently. How should I organize partitions in terms of table spaces? Is it a good idea to have "old" data (read only) partitions on separate table spaces?
It is often convenient, and sometimes very important, to separate data into different tablespaces based on some aspect of functionality. The performance thing was mooted (badly) in an era when discs were small and (disk) partitions were hard; but all your other examples of why to split are potentially valid for administrative. Big/Small, table/index, old/new, read-only/read-write, fact/dimension etc.
For data warehouses a fairly common practice is to identify some sort of aging pattern for the data, and try to pick a boundary that allows you to partition data so that a large fraction of the data can eventually be made read-only: using tablespaces to mark time-boundaries can be a great convenience - note that the tablespace boundary need not match the partition boudary - e.g. daily partitions in a monthly tablespace. If you take this type of approach, you might have a "working" tablespace for recent data, and then copy the older data to "time-specific" tablespace, packing it and making it readonly as you do so.
Tablespaces are (broadly speaking) about strategy, not performance. (Temporary tablespaces / tablespace groups are probably the exception to this thought.)
Regards
Jonathan Lewis

"ERROR: Could not read block 64439 of relation 1663/16385/16658: Result too large"

Hi,
I've already archived a lot of assets in my final cut server but since one week there is a message appearing when I click on an asset and choose "Archive". The pop-up says: "ERROR: Could not read block 64439 of relation 1663/16385/16658: Result too large"
Does anyone know what's the problem and/or have any suggestions to solve my problem?! I can't archive anymore since the first appearance of this message.
What happened before?
-> I archived some assets via FCS and then transfered the original media to an offline storage media. That system worked fine for the last months and my normal server stays quit small in storage use. But now, after I added some more new productions and let FCS generate the assets, it doesn't work anymore...
It's not about the file size - I tried even the smallest file I found in some productions.
It's not a particular production - I tried some different productions.
It's not about the storage - there's a lot of storage left on my server.
So, if someone knows how get this server back on the road - let me know.
THNX!
Chris

I would really appreciate some advice re: recent FCS search errors.
We're having similar issues to C.P.CGN's 2 year old post, it's only developed for us in the last few weeks.
Our FCS machine is running 10.6.8 mac os and 1.5.2 final cut server with the latest
OS 10.6.x updates.
FCS is still usable for 6 of 8 offliners, but on some machines, searching assets presents "ERROR: could not read block 74012 of relation1663/16385/16576: Input/output error."
Assuming the OS and/or data drives on the FCS machine were failing, I cloned the database drive today and will clone the OS drive tomorrow night, but after searching the forums and seeing similar error messages I'm not so sure.
FCS has been running fine for last 4 years, minus the recent Java security issues.
Thanks in advance, any ideas appreciated!
cheers,
Aaron Mooney,
Post Production Supervisor.
Electric Playground Daily, Reviews On The Run Daily, Greedy Docs.
epn.tv

Can't change default block size in dbca

10.1.0.3
solaris
I am using the dbca to create a database. When I go to the sizing screen and try to change the default block size this option is always greyed out at 8k.
does anyone know why? this happens even when i pick a data warehouse template.

There is a reason Oracle uses 8K as the default database block size for their warehouse template. Changing the default block size to a larger size generally does not result in better performance when both databases are allocated the exact same SGA memory allocations.
HTH -- Mark D Powell --

ORA-00204: error in reading (block string, # blocks string) of controlfile

dear all
when i start db
with command sqlplus "/as sysdba"
at the end it generate an error
C:\Documents and Settings\idsadm>sqlplus "/as sysdba"
SQL*Plus: Release 10.2.0.1.0 - Production on Mon Oct 20 12:47:37 2008
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 557842432 bytes
Fixed Size                  1250140 bytes
Variable Size             289410212 bytes
Database Buffers          264241152 bytes
Redo Buffers                2940928 bytes
ORA-00204: error in reading (block 3, # blocks 50) of control file
ORA-00202: control file: 'F:\ORACLE\IDS\SAPDATA1\CNTRL\CNTRLIDS.DBF'
ORA-27091: unable to queue I/O
ORA-27070: async read/write failed
OSD-04006: ReadFile() failure, unable to read from file
O/S-Error: (OS 23) Data error (cyclic redundancy check).

dear karan & all
i have copied "control file" from another location but now it generate an error
SQL> startup
ORACLE instance started.
Total System Global Area 557842432 bytes
Fixed Size                  1250140 bytes
Variable Size             289410212 bytes
Database Buffers          264241152 bytes
Redo Buffers                2940928 bytes
ORA-00211: control file does not match previous control files
ORA-00202: control file: 'F:\ORACLE\IDS\SAPDATA1\CNTRL\CNTRLIDS.DBF'
SQL>
now tell me what can i do
regard

Mirrored RAID: MediaKit reports block size error

I am trying to create a 2nd set up backup drives for my photos. I have two new iomega 2TB drives, which look essentially identical to drives I'm currently using as my primary backups as a mirrored RAID set.
I can start the process with freshly erased and reformatted drives (with the default mac format, extended, journaled, unencrypted, not case-sensitive). And after a minute or three, I see
"MediaKit reports block size error, usually caused by not being a multiple of 512."
The RAID options are Mirrored RAID, Mac extended journaled, and options settings are default.
I see several series of posts with complaints about encrypting RAIDs and disk block sizes, but not unencrypted errors. I actually started out trying to do this with the 2006 MBP running 10.6.8 and got a different error: "POSIX reports: the operation couldn't be completed. Operation not permitted." I wasn't sure whether the 2TB RAID I already have was set up iwth the older or newer computer--it was definitely before I put Lion on this one--so I tried this one and now have a different error.
Any idea what the problem might be?

Update: I spent some time on the phone with an Apple support RAID expert, and couldn't figure out what the error was; we couldn't bypass it by playing with partitions on the drives, or any of another couple of manuevers that I've already forgotten. He noted that his own searches were showing a lot of mentions of similar problems but only with Iomega drives, and he was finding the same links I found earlier about problems creating encrypted drives. Now trying to decide if it's worth throwing more good money after bad for a call with Iomega support, and waiting to see if the iomega forum is at all helpful.

RAID block size for final cut pro x

Just got one of the new late 2012 27" iMacs and a 6 TB LaCie Thunderbolt drive. Can finally edit the video I took last spring. I'll be using Final Cut Pro X, and doing a lot of multicam stuff with 4 or 5 views and a separate audio track. The LaCie came formatted as a mirrored RAID. I'm going to change that to 0 (Striped RAID set), but am wondering what block size to set. The default is 32k, but I have read that this ought to be increased to the max (256k) for video editing. I have also read it should NOT be increased. And the posts I have read have all been at least 3 years old. So let me ask you all--what block size would you recommend for my situation?
Thanks in advance!

Hi Eddie...
This depends on what kind of source footage you are editing....
For compressed Video, Audio and Uncompressed audio 128k
I have only had BAD results with 256k. 64 is also weird. Whereas 32 is fine.
All my RAIDs have 128k for audio/video editing
you can go further if you editing Image Sequences.. but according to my own findings and I have been dealing with raid since years.... 128k does the job the best.
Rule of thumb.... The smaller the file sizes you are putting the RAID the smaller the block size. And vice versa.
I.e. You would cripple the raid performance if storing a database on it, having a block size of 256. In case of servers and OS 32k would be a good choice, perhaps even 16k if supported.

OSD-04001: invalid logical block size (OS 2800189884)

My Windows 2003 crashed which was running Oracle XE.
I installed Oracle XE on Windows XP on another machine.
I coped my D:\oracle\XE10g\oradata folder of Win2003 to the same location in WinXP machine.
When I start the database in WinXP using SQLPLUS i get the following message
SQL> startup
ORACLE instance started.
Total System Global Area 146800640 bytes
Fixed Size 1286220 bytes
Variable Size 62918580 bytes
Database Buffers 79691776 bytes
Redo Buffers 2904064 bytes
ORA-00205: error in identifying control file, check alert log for more info
I my D:\oracle\XE10g\app\oracle\admin\XE\bdump\alert_xe I found following errors
starting up 1 dispatcher(s) for network address '(ADDRESS=(PARTIAL=YES)(PROTOCOL=TCP))'...
starting up 4 shared server(s) ...
Oracle Data Guard is not available in this edition of Oracle.
Wed Apr 25 18:38:36 2007
ALTER DATABASE MOUNT
Wed Apr 25 18:38:36 2007
ORA-00202: control file: 'D:\ORACLE\XE10G\ORADATA\XE\CONTROL.DBF'
ORA-27047: unable to read the header block of file
OSD-04001: invalid logical block size (OS 2800189884)
Wed Apr 25 18:38:36 2007
ORA-205 signalled during: ALTER DATABASE MOUNT...
ORA-00202: control file: 'D:\ORACLE\XE10G\ORADATA\XE\CONTROL.DBF'
ORA-27047: unable to read the header block of file
OSD-04001: invalid logical block size (OS 2800189884)
Please help.
Regards,
Zulqarnain

Hi Zulqarnain,
Error OSD-04001 is Windows NT specific Oracle message. It means that the logical block size is not a multiple of 512 bytes, or it is too large.
So what you can do? Well you should try to change the value of DB_BLOCK_SIZE in the initialization parameter file.
Regards

ORA-00349: failure obtaining block size

I am trying to drop and recreate ONLINE redo logs on my STANDB DATABASE (11.1.0.7)., but i am getting the below error.
On primary, we have done the changes., ie we added new logfile with bigger size and 3 members. When trying to do the same on Standby we are getting this error.
Our database is in Active DG Read only mode and the oracle version is 11.1.0.7.
I have deffered the log apply and cancelled the managed recovery, and dg is in manual mode.
SQL> alter database Add LOGFILE GROUP 1 ('+DT_DG1','+DT_DG2','+DT_DG3') SIZE 1024M;
alter database Add LOGFILE GROUP 1 ('+DT_DG1','+DT_DG2','+DT_DG3') SIZE 1024M
ERROR at line 1:
ORA-00349: failure obtaining block size for '+DT_DG1'

888442 wrote:
I am trying to drop and recreate ONLINE redo logs on my STANDB DATABASE (11.1.0.7)., but i am getting the below error.
On primary, we have done the changes., ie we added new logfile with bigger size and 3 members. When trying to do the same on Standby we are getting this error.
Our database is in Active DG Read only mode and the oracle version is 11.1.0.7.
I have deffered the log apply and cancelled the managed recovery, and dg is in manual mode.
SQL> alter database Add LOGFILE GROUP 4 ('+DT_DG1','+DT_DG2','+DT_DG3') SIZE 1024M;
alter database Add LOGFILE GROUP 4 ('+DT_DG1','+DT_DG2','+DT_DG3') SIZE 1024M
ERROR at line 1:
ORA-00349: failure obtaining block size for '+DT_DG1'First why you are dropping & recreating online redo log files on standby.
On standby only standby redo log files will be used. Not sure what you are trying to do.
here is example how to create online redo log files, Check that diskgroup is mounted and have sufficient space to create.
sys@ORCL> select member from v$logfile;
MEMBER
C:\ORACLE\ORADATA\ORCL\REDO03.LOG
C:\ORACLE\ORADATA\ORCL\REDO02.LOG
C:\ORACLE\ORADATA\ORCL\REDO01.LOG
sys@ORCL> alter database add logfile group 4 (
2     'C:\ORACLE\ORADATA\ORCL\redo_g01a.log',
3     'C:\ORACLE\ORADATA\ORCL\redo_g01b.log',
4     'C:\ORACLE\ORADATA\ORCL\redo_g01c.log') size 10m;
Database altered.
sys@ORCL> select member from v$logfile;
MEMBER
C:\ORACLE\ORADATA\ORCL\REDO03.LOG
C:\ORACLE\ORADATA\ORCL\REDO02.LOG
C:\ORACLE\ORADATA\ORCL\REDO01.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01A.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01B.LOG
C:\ORACLE\ORADATA\ORCL\REDO_G01C.LOG
6 rows selected.
sys@ORCL>
Your profile:-
888442
     Newbie
Handle:      888442
Status Level:      Newbie
Registered:      Sep 29, 2011
Total Posts:      12
Total Questions:      8 (7 unresolved)
Close the threads if answered, Keep the forum clean.

Data block size

I have just started reading the concepts and I got to know that Oracle database data is stored in data blocks. The standard block size is specified by
DB_BLOCK_SIZE init parameter. Additionally we can specify upto 5 other block sizes using DB_nK_CACHE_SIZE parameter.
Let us say I define in the init.ora
DB_BLOCK_SIZE = 8K
DB_CACHE_SIZE = 4G
DB_4K_CACHE_SIZE=1G
DB_16K_CACHE_SIZE=1G
Questions:
a) Does this mean I can create tablespaces with 8K, 4K and 16K block sizes only?
b) whenever I query data from these tablespaces, it will go and sit in these respective cache sizes?
Thanks in advance.
Neel

yes, it will give error message if you create tablespace with non standard block size without specify the db_nk_cache_size parameter in the init parameter file .
Use the BLOCKSIZE clause of the CREATE TABLESPACE statement to create a tablespace with a block size different from the database standard block size. In order for the BLOCKSIZE clause to succeed, you must have already set the DB_CACHE_SIZE and at least one DB_nK_CACHE_SIZE initialization parameter. Further, and the integer you specify in the BLOCKSIZE clause must correspond with the setting of one DB_nK_CACHE_SIZE parameter setting. Although redundant, specifying a BLOCKSIZE equal to the standard block size, as specified by the DB_BLOCK_SIZE initialization parameter, is allowed.
The following statement creates tablespace lmtbsb, but specifies a block size that differs from the standard database block size (as specified by the DB_BLOCK_SIZE initialization parameter):
CREATE TABLESPACE lmtbsb DATAFILE '/u02/oracle/data/lmtbsb01.dbf' SIZE 50M
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 128K
BLOCKSIZE 8K;
reference:-http://download.oracle.com/docs/cd/B28359_01/server.111/b28310/tspaces003.htm

How to know the OS block size ?

Hi all
I want to know how to get the OS block size of my server ?
For example if my server is Windows 2000 Professionnal , how can I get the size of my OS block size ?
Thank you

One way to find is to right click the drive in Windows Explorer and click Format (Not actually formatting it).
In the popup window, you would see the "Allocation unit size" for the selected drive. Click "Close" to exit when done.

Install Recommendations (RAID, ASM, Block Size etc)

Hello,
I am about to set up a new Oracle 10.2 Database server. In the past, I used RAID5 since 1) it was a fairly small database 2) there were not alot of writes 3) high availability 4) wasted less space compared to other RAID techniques.
However, even though our database is still small (around 100GB), we are noticing that when we update our data, the time it takes is starting to grow to a point whereby the update that used to take about an hour, now takes 10-12 hours or more. One thing we noticed that if we created another tablespace which had a block size of 16KB versus our normal tablespace which had a block size of 8KB, we almost cut the update time in half.
So, we decided that we should really start from scratch on a new server and tune it optimally. Here are some questions I have:
1) Our server is a DELL PowerEdge 2850 with 4x146GB Hard Drives (584GB total). What is the best way to set up the disks? Should I use RAID 1+0 for everything? Should I use ASM? If I use ASM, how is the RAID configured? Do I use RAID0 for ASM since ASM handles mirroring and striping? How should I setup the directory structure? How about partitioning?
2) I am installing this on Linux and when I tried on my old system to use 32K block size, it said I could only use 16K due to my OS. Is there a way to use a 32K block size with Linux? Should I use a 32K block size?
Thanks!

The way I usually handle databases of that size if you don't feel like migrating to ASM redundancy is to use RAID-10. RAID5 is HORRIBLY slow (your redo logs will hate you) and if your controller is any good, a RAID-10 will be the same speed as a RAID-0 on reads, and almost as fast on writes. Also, when you create your array, make the stripe blocks as close to 1MB as you can. Modern disks can usually cache 1MB pretty easily, and that will speed the performance of your array by a lot.
I just never got into ASM, not sure why. But I'd say build your array as a RAID-10 (you have the capacity) and you'll notice a huge difference.
16k block size should be good enough. If you have recordsets that are that large, you might want to consider tweaking your multiblock read count.
~Jer

What USB storage devices have a block size of 512 bytes?

After pulling my hair out for weeks trying to get a usb hard drive to work with my new AirPort Extreme (802.11n), I ran across this
http://docs.info.apple.com/article.html?artnum=305038
AirPort Extreme (802.11n): USB storage device supported formats and protocols
You can connect USB-based storage devices to an AirPort Extreme (802.11n). Learn which formats and protocols are supported.
The AirPort Extreme (802.11n) supports USB storage devices that have a block size of 512 bytes, and are formatted as Mac OS Extended (HFS-plus), FAT16, or FAT32. Not all USB storage devices use a block size of 512 bytes.
The AirPort Extreme (802.11n) shares storage devices based on the format used to initialize the storage device. For example, if HFS-plus formatting was used, AFP and SMB/CIFS protocols are used to share the device on the network. If FAT16 or FAT32 was used, SMB/CIFS protocols are used.
The AirPort Extreme (802.11n) works with disks that have a single partition and are not software RAID volumes (no more than one volume per physical disk). If the disk is a self-contained RAID that presents itself to a computer as a single volume requiring no software support, then it is supported.
Note: Use AirPort Disk Utility to discover and mount AirPort Extreme-based volumes over the network.
Now, this information is not easily obtainable while
shopping for a new usb hard drive. How do I find out which
ones support this 512 byte block size????
Would have bee nice to know that not all usb hard drives
are supported by the AirPort Extreme (802.11n) before I
purchased it.
Thanks
J Riley

Duane posted a link to an unofficial 802.11n Airport Extreme Hard Drive Compatibility List.
http://www.ifelix.co.uk/tech/8014.html
Still not enough information to make an informed purchase that
will work.

O/S read block size.

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