Repeated Overlapped Extent Allocation
I recently began having problems with "Overlapped Extent Allocation" errors on my hard drive on my "Late 2010" MacBook Air. When it first happened, I formatted the drive, reinstalled OSX 10.7, and restored my data. Within a month or so, the drive was corrupted again with the same errors. So, I replaced the hard drive, reinstalled OSX, and restored my data. Now, only a couple weeks after doing this, I am having the same problem yet again. What could be causing this to happen so frequently?
Linc,
Thanks for the reply. Unfortunately, I've already replaced the drive and it's doing the same thing on the new drive. I suppose it's possible that I got a bad drive, but it's hard to imagine it having exactly the same error as the previous drive.
Similar Messages
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Overlapped extent allocation, backing up and erase/install
Can't boot up my G4 flat panel iMac. Have tried safe boot mode - hangs on grey screen and spinning gears. Ran Disk Repair from install disk which reported 'overlapped extent allocation' files - dozens of 'em, so decided to back up users folders to g5 tower using target disk mode and I can access the iMac's hard drive through TDM.
Having read this technical document:
http://support.apple.com/kb/HT1553?viewlocale=en_US#3c
it specifies that that I have to log into the imac as a root user to copy the user folders to the G5 but as I can't log in to it am I OK just to access and copy the user folders from the imac via target disk mode? (I've started this but, for example, when copying one of the user folders - 35GB of content - the copied folder correctly has 16 folders within, but has a few thousand bytes of data less than the original folder - why is this and will it cause problems after erasing the imac's drive and attempting to copy back the user directories?
I have read elsewhere that I can search for the problematical Overlapped Extent Allocation files in the DamagedFiles directory but can I safely delete these and how can I tell if I can or can't and how do I find them? (the reasoning being that if I can safely delete these then the imac may boot up OK)
When quitting the installer menu on the imac (when booting from the install disk) I am prompted to either quit or choose startup disk. If I choose the latter option will the imac boot from the install disk enabling me to back up the user folders to an external drive using the method recommended in the technical document I previously referred to (i.e logging in as a root user)?
Thanks for any helpThere are a couple of ways to deal with the problem. See the following:
Handling 'overlapped extent allocation' errors reported by Disk Utility or fsck;
Or buy Disk Warrior which will fix the problem for you and any other directory related problems that Disk Utility does not fix.
However, the most effective solution is to erase the drive and reinstall OS X. Since you are accessing the drive via TDM, copy your personal data to a backup drive or folder on the other computer. There's no benefit to copying the entire Home folder because it may contain files affected by the problem. Better to copy only your data files. You will have to do some software reinstalling and re-registering, but that's better than having damaged files. -
Hi all,
I'm trying to solve a number of overlapped extent allocations (OS X 10.2.8) using the command line solution described in http://docs.info.apple.com/article.html?artnum=25770. I have previously tried to fix the HD using Tech Tool deluxe, but the repair phase seems to hang after a few hours when the rate of block processing slows down to one per several minutes - suggesting a time to complete of about 11 days!!
Starting with 9 overlaps, I've deleted offending files for 6 of them - they were either preference or cache files that could go without any knock-on impact.
I'm now left with the following affected files:
Users/mike/Library/Mail/Mailboxes/Mailgroups/GPSrunners.mbox/Incoming_mail
/private/var/run/cron.pid
/private/var/run/utmp
Can anyone please advise how to deal with these?
I'm happy to lose the mailbox if I delete the first one.
What do the 2nd and 3rd files do?? Will they cripple my OS if I delete them? I have a backup of my HD on an external drive taken a few weeks ago so the user data will not be current but the OS should be an intact backup of the OS - I can certainly boot from it. Is there a way to replace them from the HD, and if so do I have to do that from the command line (they don't seem to be visible to the finder).
Grateful for any help - in nice simple steps for someone whose command line knowledge was limited to fsck until today!
thanks,
Mike
iMac800 Mac OS X (10.2.x)Kappy, Fifthwheel, WJ,
Thanks for your excellent help.
I've deleted the mbox and cron.pid files - the allocation error asociated with the utmp file just seems to have gone away. Checking the HD by fsck or Disk Uitility/First Aid from an external drive says the disk is OK.
HOWEVER, I still have the problem reported here:
http://discussions.apple.com/thread.jspa?threadID=583008&tstart=0
Could this login difficulty be caused by the utmp file being damaged? If so, how can I replace it by a good one if, as WJ suggests, it will not be recreated automatically if I delete it?
Can I use the one on my external drive which has the OS backed up, and if so how do I actually move it (command line or finder)?
thanks,
Mike
iMac800 Mac OS X (10.2.x)
iMac800 Mac OS X (10.2.x) -
Fixing "overlapped extent allocation (file 7d)"...
Hi,
While running fsck i get the error "overlapped extent allocation (file 7d)"
I've read the guide on how to delete problematic files, but does this apply to my error (i.e. it's not a 7-digit file number)?
btw, i tried running "find / -inum 7". The hard drive buzzes a bit then displays the normal prompt (sh-2.05) and not the path to my problem file...
Any ideas?
Thanks
mac os x 10.2.3By "regular mode", he means after the system has booted to the login window. Most people who run fsck do it from single-user mode (no GUI, no Terminal; just a command line).
When you try 'sudo -s' from a non-administrator account, it will fail ("(this user) is not in the sudoers file..."). Thus when you typed the 'find / -inum 7', you are doing the search as the non-administrative user rather than as root, which means that your access to the file system is limited to the files and directories that that user is allowed to read (usually only system files and its own home directory). So no, the directories that yield ": Permission denied" are not corrupt; they just aren't yours, so you're not allowed to search them.
Disk Warrior won't do you much good if you try to run it from a non-administrator account; it'll suffer the same restrictions you encountered with your 'find'.
Your best bet is to print reboot to single-user mode and attempt to fix the problem there. -
My iBook is not starting, so I ran the start up disc, and the diagnostic said I had an overlapped extent allocation. So I want to back up before I reinstall OS X, but I do not not know how to back up from either the start up or safe mode. Can someone help me? Thanks so much.
Angela:
When I ran the Disk Utility it said it was fixed, but I still could not start up the computer. I actually ran the Utility a couple of times.
Yet in your first post in the topic you said:
so I ran the start up disc, and the diagnostic said I had an overlapped extent allocation.
If Disk Utility said it was fixed, what "start up disc" did you run?
As Doug pointed out, overlapping extent allocation files is a directory issue that needs to be addressed by a utility like Disk Warrior or Tech Tool Pro. Backing up and re-installing is an acceptable solution, but much more invasive.
One of the causes of overlapping extent allocation files is an overfull internal Hard Disk Drive. If you have less than 10% of available capacity on your HDD you should consider leaning down the contents of the drive or getting a larger HDD.
Good luck.
cornelius
Message was edited by: cornelius -
Why use uniform extent allocation?
version- 11.2.0.2.0
Hello guys, I've been reading UNIFORM vs AUTOALLOCATE extent allocation.
I've read the following articles.
https://blogs.oracle.com/datawarehousing/entry/parallel_load_uniform_or_autoallocate
Ask Tom: On Loading and Extents
https://forums.oracle.com/thread/2518951
From what I understood, autoallocate trumps the uniform in all scenarios (unless I am missing something).
In the thread "AUTOALLOCATE vs UNIFORM SIZE"
for the benefits of autoallocate and uniform size allocation Kh$n wrote
Benefits of AUTOALLOCATE
* Prevents space fragmentation.
Benefits of UNIFORM extent sizes
* Prevents fragmentation.
(I dont understand what is the difference between those two fragmentation prevention, are those benefits one and the same?)
even in scenarios where we know exactly how much data will be loaded, there is always a chance of extent wastage and with out extent trimming that space will be unusable.
Can someone please explain in which cases we use uniform extent allocation?
for suppose we use uniform extent allocation and we have lot of unused space from the extent allocation, can that space be reclaimed using shrink space command for tables and indexes?
Thank YouExtent trimming, to the best of my knowledge, is something that only happens when you are using parallel query to do large loads, not something that happens during normal OLTP type operations. As with anything called "automatic" in Oracle, though, the internals are subject to change across versions (and patchsets) and are not necessarily documented, so it is entirely possible for behaviors to change over time. Relying on specific internal behaviors is generally not a good idea.
The example I gave (assuming you reverse the truncating of A and the loading of C, as Hemant pointed out) produces "fragentation" when you're using automatic extent management. It's not a particularly realistic scenario, but it is possible. If you never delete data, never truncate tables, (and, presumably, never shrink tables), extents would never be deallocated and there would, therefore, never be holes. That is just as true of ancient dictionary managed tablespaces as well as locally managed tablespaes whether you're using uniform or autoallocated extents.
Shrinking a table has nothing to do with defragmenting a tablespace. It is simply compacting the data in the table and then potentially deallocating extents. You can do that with any locally managed tablespace. There is still the possibility, of course, that you have just enough data in the table that you need to allocate 1 extra extent when you only need space for 1 row in 1 block. So there may be some number of MB of "wasted" space per segment (though, again, this is generally not something that is a practical concern since the data in tables generally changes over time and it's generally not worth the effort of worrying about a few MB).
Justin
For your third question, assuming both extents are part of the same segment, assuming that the space is actually usable based on things like the PCTUSED setting of the table, and assuming a nice, simple conventional path insert in a single-user, Oracle would use the free space in the extent for new inserts before allocating a new extent. Oracle generally doesn't allocate new extents unless it needs to (there are caveats to this-- if the only blocks with free space have a relatively large fraction of their space used such that a particular new insert only fits in 1 of the 1 million blocks in the currently allocated extents, Oracle will potentially give up before finding the 1 in a million block that it would need an may allocate a new extent).
Message was edited by: JustinCave -
Determining Extent Allocation Type
Does anyone know how you tell if a tablespace has been configured to use UNIFORM extent allocation or AUTO ALLOCATE . I can see in dba_tablespaces if the extent is dictionary or locally managed. I can also see if it is using ASSM or not but I am struggling to see where the actual method of extent allocation is recorded
thanks,
Jimhttp://docs.oracle.com/cd/B19306_01/server.102/b14237/statviews_4157.htm
ALLOCATION_TYPE -
Hi Guys,
I had a question regarding extent allocation to a segments. In a RAC environment we allocate extent to specific instance, why is it so?
As we know extent are the space allocated at stogare level, so why do we allocate to specific instance in RAC?
Is there any specific reason to do so...
Please suggest...
Thanks!can you show me an example where you allocated an "extent" to a specific instance? Are you using ASM or shared file system - if shared FS, which one? Bigfile tablespace? Smallfile tablespace?
-
Change extent allocation in tablespace
Hi All,
Database Version : 11.1.0.6
I have a LMT tablespace with uniform extent of 192 K. It has been in use since long .
Is it possible to change the extent allocation to AUTOALLOCATE now ?
If not , is there any workaround ..
Thankshi..
there is no "alter table space" syntax for changing extent management from uniform to auto allocate. Hence, you must re-define the table space to change the extent management:
* Backup the table space
* Export the table space data
* Drop and re-allocate the table space
* Import the table space -
10g Local Extent Allocation "UNIFORM"
Hello all,
I'm in the process of 8i (Dictionary extent) to 10g (Local extent) migration, and I have a question.
is "USER" allocation in 8i same as "UNIFORM?"
Thanks!ok thank you. Here's the steps I've taken:
1. Pre-created the tablespace as "UNIFORM" on 10g
2. Ran IMP (dmp from 8i, as "USER")
3. ALLOCATION_TYPE still shows as "UNIFORM"
So basically, because the purpose was to EXP/IMP from server A to server B, I did not do take any upgrade steps, just simple EXP/IMP. Would the upgrade option automatically have changed allocation_type to "USERS" from "UNIFORM?"
if you see something wrong with below, please kindly let me know...
SQL> select tablespace_name, extent_management, allocation_type, contents from dba_tablespaces;
TABLESPACE_NAME EXTENT_MAN ALLOCATIO CONTENTS
SYSTEM LOCAL USER PERMANENT
SYSAUX LOCAL SYSTEM PERMANENT
USERS LOCAL SYSTEM PERMANENT
TOOLS LOCAL SYSTEM PERMANENT
TEMP LOCAL UNIFORM TEMPORARY
TEMP_ACDB LOCAL UNIFORM TEMPORARY
USERS_ACDB LOCAL SYSTEM PERMANENT
UNDO01 LOCAL SYSTEM UNDO -
Hi ASM experts ,
this is written in oracle11gr2 workshop1 lesson5 page 22
for the first 20,000 extents, the extent size is equal to the AU size. After 20,000 extents and up to 40,000 extents, the extent sets are always allocated 8 at a time with the extent size equal to 4*AU size. If the AU size is 1 MB, this means the ASM file will grow 64 MB at a time (8 * 4 * 1 MB). If the file is coarse-grained striped then it is striped across the 8 extent sets with stripes of 1 AU. Striping is always done at the AU level, not at the extent level. Thus every AU of a coarse-grained file is on a different disk than the previous AU of that file no matter how large the file. After 40,000 extents, the extents are still allocated 8 at a time, but with an extent size equal to 16*AU size.
first of all i don't know how 8*4*1 will be 64
and my question is does oracle allocate 8 extents at a time whatevre number of previous allocated extents under 20000 or over 40000?
thank you for reading.user475845 wrote:
Hi ASM experts ,
this is written in oracle11gr2 workshop1 lesson5 page 22
for the first 20,000 extents, the extent size is equal to the AU size. After 20,000 extents and up to 40,000 extents, the extent sets are always allocated 8 at a time with the extent size equal to 4*AU size. If the AU size is 1 MB, this means the ASM file will grow 64 MB at a time (8 * 4 * 1 MB). If the file is coarse-grained striped then it is striped across the 8 extent sets with stripes of 1 AU. Striping is always done at the AU level, not at the extent level. Thus every AU of a coarse-grained file is on a different disk than the previous AU of that file no matter how large the file. After 40,000 extents, the extents are still allocated 8 at a time, but with an extent size equal to 16*AU size.
first of all i don't know how 8*4*1 will be 64
and my question is does oracle allocate 8 extents at a time whatevre number of previous allocated extents under 20000 or over 40000?
thank you for reading.Hi,
Documentation says:
The extent size of a file varies as follows:
Extent size always equals the disk group AU size for the first 20000 extent sets (0 - 19999).
Extent size equals 4*AU size for the next 20000 extent sets (20000 - 39999).
Extent size equals 16*AU size for the next 20000 and higher extent sets (40000+).
Please check : http://docs.oracle.com/cd/E11882_01/server.112/e18951/asmcon.htm#BABCGDBF
Figure 1-4 Oracle ASM File Allocation in a Disk Group+
Regards
Mahir M. Quluzade -
How many extents allocated when table created?
I am using Oracle 9,
is the number going to be what we specified by minextents?
thanksSrinivas,
You said,
If its AUTOALLOCATE , Oracle starts with 1 extent of 64KB , then 128KB as the first extent becomes full, then 256KB so on....
Can you help me in understanding this statement?I don't think that its true. See here,
SQL> select * from V$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE 10.2.0.1.0 Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
SQL> drop tablespace test including contents and tablespaces;
drop tablespace test including contents and tablespaces
ERROR at line 1:
ORA-00905: missing keyword
SQL> drop tablespace test including contents and datafiles;
Tablespace dropped.
SQL> create tablespace test datafile 'd:\test.dbf' size 100m extent
ocal autoallocate ;
Tablespace created.
SQL> select tablespace_name,initial_extent,next_extent from dba_tab
2 where tablespace_name='TEST'/
3
SQL> select tablespace_name,initial_extent,next_extent from dba_tab
2 where tablespace_name='TEST'
3 /
TABLESPACE_NAME INITIAL_EXTENT NEXT_EXTENT
TEST 65536
SQL> --Creating a table inside in this tablespace
SQL> create table t as select * from dba_objects;
Table created.
SQL> alter table t move tablespace test;
Table altered.
SQL> select tablespace_name, extent_id, bytes/1024, blocks
2 from user_extents
3 where segment_name = 'T';
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 0 64 8
TEST 1 64 8
TEST 2 64 8
TEST 3 64 8
TEST 4 64 8
TEST 5 64 8
TEST 6 64 8
TEST 7 64 8
TEST 8 64 8
TEST 9 64 8
TEST 10 64 8
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 11 64 8
TEST 12 64 8
TEST 13 64 8
TEST 14 64 8
TEST 15 64 8
TEST 16 1024 128
TEST 17 1024 128
TEST 18 1024 128
TEST 19 1024 128
TEST 20 1024 128
21 rows selected.
SQL>
SQL> insert into t select * from t;
50356 rows created.
SQL> /
100712 rows created.
SQL> /
201424 rows created.
SQL> /
402848 rows created.
SQL> commit;
Commit complete.
SQL> analyze table t compute statistics;
Table analyzed.
SQL> select tablespace_name, extent_id, bytes/1024, blocks
2 from user_extents
3 where segment_name = 'T';
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 0 64 8
TEST 1 64 8
TEST 2 64 8
TEST 3 64 8
TEST 4 64 8
TEST 5 64 8
TEST 6 64 8
TEST 7 64 8
TEST 8 64 8
TEST 9 64 8
TEST 10 64 8
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 11 64 8
TEST 12 64 8
TEST 13 64 8
TEST 14 64 8
TEST 15 64 8
TEST 16 1024 128
TEST 17 1024 128
TEST 18 1024 128
TEST 19 1024 128
TEST 20 1024 128
TEST 21 1024 128
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 22 1024 128
TEST 23 1024 128
TEST 24 1024 128
TEST 25 1024 128
TEST 26 1024 128
TEST 27 1024 128
TEST 28 1024 128
TEST 29 1024 128
TEST 30 1024 128
TEST 31 1024 128
TEST 32 1024 128
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 33 1024 128
TEST 34 1024 128
TEST 35 1024 128
TEST 36 1024 128
TEST 37 1024 128
TEST 38 1024 128
TEST 39 1024 128
TEST 40 1024 128
TEST 41 1024 128
TEST 42 1024 128
TEST 43 1024 128
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 44 1024 128
TEST 45 1024 128
TEST 46 1024 128
TEST 47 1024 128
TEST 48 1024 128
TEST 49 1024 128
TEST 50 1024 128
TEST 51 1024 128
TEST 52 1024 128
TEST 53 1024 128
TEST 54 1024 128
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 55 1024 128
TEST 56 1024 128
TEST 57 1024 128
TEST 58 1024 128
TEST 59 1024 128
TEST 60 1024 128
TEST 61 1024 128
TEST 62 1024 128
TEST 63 1024 128
TEST 64 1024 128
TEST 65 1024 128
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 66 1024 128
TEST 67 1024 128
TEST 68 1024 128
TEST 69 1024 128
TEST 70 1024 128
TEST 71 1024 128
TEST 72 1024 128
TEST 73 1024 128
TEST 74 1024 128
TEST 75 1024 128
TEST 76 1024 128
TABLESPACE_NAME EXTENT_ID BYTES/1024 BLOCKS
TEST 77 1024 128
TEST 78 1024 128
TEST 79 8192 1024
TEST 80 8192 1024
TEST 81 8192 1024
82 rows selected.
SQL>Its not working in the way youmentioned. The extents are of 65kb till 16 extents than it changes to 1024kb untill 78 and then 8192 kb. Is it something that I am missing?
Aman.... -
Error: The underlying task reported failure on exit / INVALID EXTENT ENTRY
In trying to verify my HD, I get this error message:
Verify and Repair disk “Macintosh HD”
Checking HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Invalid extent entry
Volume check failed.
Error: The underlying task reported failure on exit
1 HFS volume checked
1 volume could not be repaired because of an error
I've tried Disk Utility (not from startup volume) with no luck. I've also run DiskWarrior several times and still get the same message... What am I missing? How do you repair an INVALID EXTENT ENTRY? Is my HD about to bite the dust?
Any help would be much appreciated!
iMac G5 Mac OS X (10.4.6) 1.8 Ghz / 768mb ram1derfullymad,
Welcome to Apple Discussions.
I am surprised that Diskwarrior was not able to take care of this problem, but Handling "overlapped extent allocation" errors reported by Disk Utility or fsck may provide the ultimate solution for you.
Make sure to use Disk Utility to check the S.M.A.R.T. status of your drive. If you get a good report the drive should be OK.
This problem is a characteristic of a full Hard Drive. If that describes your Hard Drive, Freeing space on your Mac OS X startup disk, by Dr. Smoke may prove to be helpful.
;~) -
Startup Problems (and more) with my G5 PowerMac
OK, here goes...
This started this morning. I came into my office and found that my G5 had finished burning the DVD I had started last night before bed (some avi's in Toast, for what it's worth). Removed the DVD, shut down Toast and tried to drag the avi's to the trash. Instead of behaving normally, this (just to be clear, I mean dragging the avi's to the trash) restarted the dock and "disappeared" any open folders on the right side of the dock (as well as the open folder with the avi's on the desktop) All the folders opened back up on the desktop in a few seconds. I was able to send the other folders back to the dock, but any effort to put the avi's in the trash (one at a time or together, by dragging or right-clicking for the menu) repeated the same scenario.
Then tried to restart, which went normally until the blue bar (in the "Starting OSX window") reached the far right side. At this point, it just hung (although the blue bar still seemed to be "moving"). Tried several more times, same thing.
Then I tried resetting the SMU (unplugged it for half an hour. Didn't try the SMU reset button, as I believed that to be redundant, correct?) -- Nothing. Reset the PRAM -- Nothing.
I then tried an "Archive and Install" from my Tiger DVD. After it does it's thing (well, almost does it's thing - it doesn't finish), it has a "There were errors installing the software" message at the top of the installer window. So again, no luck.
Then I moved on to Disk Utilities and tried a Repair DisK. After writing "Overlapped Extent Allocation" (with a parenthetical file reference) about a thousand times, and "checking multi-linked files", as well as "checking catalog hierarchy" it quickly scrolls to a stop, showing "Volume Bit Map needs minor repair," "Invalid volume free block count," then "Volume Header needs minor repair," followed by 'repairing volume" and "The volume Macintosh HD could not be repaired." Finally, it says "Error: the underlying task reported failure on exit" (as well as some messages about "the (HFS) volume could not be repaired because of an error." The First Aid Failed window says that Disk Utility stopped repairing Macintosh HD because "the underlying task reported failure on exit." And that's all I could think to try.
So, any ideas on how to proceed?
I'll point out, just in case, that this was the original, pre-installed hard drive. I have another internal in there, as well as five externals.
Hoping someone can help, but dreading what I anticipate hearing.
TIA,
WarrenKarl,
This is just a note to say thanks for your help. I don't know if you'll read this, but I thought it would only be polite to make the effort.
In case you're interested, the drive is back up and working. Something you mentioned about using Tech Tool Pro (which I do have) to recover data, sparked a thought about another path to try before giving up and starting over with a clean install.
I went out and picked up a copy of DiskWarrior, and that did the trick. It was able to rebuild the directory, and from there I was able to successfully do an "Archive and Install" from my Tiger DVD. It seems most of the damage to the OS was minor, and it was just one or two of the overlapped files that were the culprits. There are a few minor things I'm still fixing: a few programs that had to be reinstalled, some drivers that needed replacing, fixing the settings for the network and one or two other minor things. However, weighing that against the idea of having to do everything over from scratch makes me feel like I got off very lightly indeed.
There are also a few other benefits that I've accrued: A new, bigger hard drive to use as my startup disc, so I don't have to struggle for space with the old 150GB one; a copy of DiskWarrior (an invaluable program, if there ever was one); and a renewed sense of urgency when it comes to maintaining my Macs. It's all to easy to become complacent when you're using a machine as stable as a Mac. And, also, a great reminder of how insidious the "creeping OS damage" can be. All-in-all,,,
So thanks again for your efforts. This wouldn't have had as happy an ending without your help. I hope you see this.
-W -
Stuck on grey screen with apple logo after failed iTunes update
I tried to install an update for iTunes 9.2 on my MacBook. During installation a box appeared telling me the update had failed. I clicked the 'Restart' button. Now it won't go past the grey screen with the apple logo and the rotating wheel; it just loads indefinitely. I have a very important document saved on the Mac which I've added to without backing it up. I'm worried that I will lose (or have already lost) a great deal of writing. Is there a way to get my computer running again without damaging my files? Because this computer was a gift, I don't have the software installation CDs that came with it (or Disk Utility). I'm also not very familiar with computers in general, so if you explain your solutions in a really basic way, I'd appreciate it. Any kind of advice would be extremely welcomed...
This one?
http://docs.info.apple.com/article.html?artnum=106214
Resolve startup issues and perform disk maintenance with Disk Utility and fsck
* Last Modified: June 25, 2009
* Article: TS1417
* Old Article: 106214
[Email this article]
[Print this page]
Symptoms
If your computer won't start up normally, you may need to use a disk repair utility to fix the issue. Mac OS X includes two utilities for this—Disk Utility and fsck (a command-line utility). You can also use these even when your computer starts just fine but you want to check the disk for possible file system issues. For Mac OS X 10.4.3 or later, check out "About live verification in Mac OS X 10.4.3 or later," below.
Important: If you're using Mac OS X 10.4 or later, you should use Disk Utility instead of fsck, whenever possible.
In some situations, file system errors may prevent your computer from starting up. This can occur after an improper shutdown, forced restart, or power interruption. If your computer shows any of the following symptoms on startup, use a disk repair utility:
* Your computer partially starts but then displays a command line in a text-only environment. You may see the message, "file system dirty, run fsck." Below it, you'll see what's called a command-line prompt, indicated by a number sign (#), that allows you to type a command. If you see this, you'll need to run fsck from the command line (see "Use fsck if necessary," below).
* Your computer starts but either it won't reach the login screen, or it may reach the login screen but not load the Desktop after you log in. However, you can start up in single-user mode.
If your computer exhibits either of the above issues, here are some things to try to get your computer back to starting up properly again. If you can't find the system discs that came with your computer, see "Use fsck," below.
Products Affected
Mac OS X 10.4, Mac OS X 10.3, Mac OS X 10.2, Mac OS X 10.1
Resolution
Try a Safe Boot
If you're using Mac OS X 10.2 or later, you can start up your computer in Safe Mode, which includes an automatic disk check and repair. If you're using Mac OS X 10.1.5 or earlier, skip to the next section. A Safe Boot, which starts up your computer into Safe Mode, may allow you to start up your computer successfully using a reduced version of the system software. To do this, follow these steps:
1. Start up in Safe Mode.
2. After the system has fully started up, restart your computer again normally.
If the computer successfully restarts, you do not need to do any more troubleshooting. If the issue persists, try Disk Utility.
Try Disk Utility
1. Start from your Mac OS X Install disc: Insert the installation disc, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Mac OS X volume.
6. Click Repair. Disk Utility checks and repairs the disk.
Tip: Always start up your computer from an Install or Restore disc when using Disk Utility to verify or repair your startup volume. Otherwise, you might see some disk error messages.
Use fsck if necessary
fsck is a command-line utility that may be able to verify and repair a disk. If you can successfully start up in Safe Mode or use Disk Utility while started up from a disc, you don't need to use fsck. Here are some situations in which fsck may be necessary.
* Your Mac OS X disc isn't available.
* Your optical drive isn't available.
* You can't start with a Safe Boot by holding the Shift key during start up.
Tip: If you use a Mac OS X Extended (Journaled) formatted volume, such as with Mac OS X 10.3 or later, you probably won't need to use fsck. If you do use it for any reason, please be aware that benign error messages can appear.
If you're not sure how your volume is formatted and you can't start up from your Mac OS X volume to find out, type the following command in a command-line interface and then press Return: diskutil info /
If you see "File System: Journaled HFS+" returned, you have a Journaled volume.
To use fsck, you must run it from the command line. Unlike using your mouse pointer to open an application to do something, you'll need to type a text command at the prompt (#) to tell fsck what to do. The Terminal application (/Applications/Utilities) and single-user mode are two examples of command-line interfaces in which you can type such commands. To use fsck:
1. Start up your computer in single-user mode to reach the command line.
Note: If necessary, perform a forced restart as described in the Emergency Troubleshooting Handbook that came with your computer. On desktop computers, you can do this by pressing the reset/interrupt button (if there is one) or holding down the power button for several seconds. On portable computers, simultaneously press the Command-Control-power keys. If your portable computer doesn't restart with this method, you may need to reset the Power Manager.
2. At the command-line prompt type:
/sbin/fsck -fy
3. Press Return. fsck will go through five "phases" and then return information about your disk's use and fragmentation. Once it finishes, it'll display this message if no issue is found:
** The volume (nameofvolume) appears to be OK
If fsck found issues and has altered, repaired, or fixed anything, it will display this message:
*** FILE SYSTEM WAS MODIFIED ***
Important: If this message appears, repeat the fsck command you typed in step 2 until fsck tells you that your volume appears to be OK (first-pass repairs may uncover additional issues, so this is a normal thing to do).
4. When fsck reports that your volume is OK, type reboot at the prompt and then press Return.
Your computer should start up normally and allow you to log in.
Additional Information
About live verification in Mac OS X 10.4.3 or later
In Mac OS X 10.4.3 or later, you can verify your Mac OS X volume while started from it. This is known as live verification, and can be used in three different ways.
Option 1: Verify your disk using Disk Utility while started from the startup disk. To find out how to do this, see this article. Please note that live verification does not involve any disk repair, so if verification finds something that should be repaired, start up from your Mac OS X Install disc and use Disk Utility as described above in "Try Disk Utility."
Option 2 (advanced): Use the command line and the command-line utility, diskutil.
1. Start up your computer and log in as an administrator.
2. Open Terminal (/Applications/Utilities).
3. At the prompt, type the following command and then press Return:
diskutil verify /
Note: Don't use this method to check non-startup volumes.
You should see messages such as the following during the disk check:
Could not unmount disk for verification, attempting live verify
Started verify/repair on volume disk0s3 Macintosh HD
Checking HFS Plus volume.
Checking Extents Overflow file.
Checking Catalog file.
Checking multi-linked files.
Checking Catalog hierarchy.
Checking Extended Attributes file.
Checking volume bitmap.
Checking volume information.
The volume Macintosh HD appears to be OK.
Mounting Disk
Verify/repair finished on volume disk0s3 Macintosh HD
Option 3 (advanced): Use the command line and the fsck_hfs -l command.
1. Start up your computer and log in as an administrator.
2. Open Terminal (/Applications/Utilities).
3. At the prompt, type the following command and then press Return to determine your filesytem ID:
df -hl
4. Look for some lines of text that look like this:
Filesystem Size Used Avail Capacity Mounted on
/dev/disk0s3 37G 20G 17G 55% /
/dev/disk0s5 37G 37G 641M 98% /Volumes/Storage
5. Make a note of the first "disk" name that appears after /dev/, such as "disk0s3." This is your filesystem ID for your startup volume.
6. At the prompt, type the following command and then press Return:
df -hl
7. Then type the following command, where "disk0s3" is your filesystem ID you noted in step 4, then press Return:
sudo fsck_hfs -l /dev/disk0s3
8. When prompted, enter your admin password, then press Return to begin the verification.
9. You should see messages like these during the disk check:
** /dev/rdisk0s3 (NO WRITE)
** Root file system
** Checking HFS Plus volume.
** Checking Extents Overflow file.
** Checking Catalog file.
** Checking multi-linked files.
** Checking Catalog hierarchy.
** Checking Extended Attributes file.
** Checking volume bitmap.
** Checking volume information.
** The volume Macintosh HD appears to be OK.
Advanced information
If you're interested in UNIX-style command-line syntax, here's a look at how a couple of flags used above can influence fsck:
* The -y flag: Tells fsck that you want to answer "yes" to all questions about fixing, repairing, or salvaging information. This is the optimal approach, as answering "no" to any question causes fsck to stop. You cannot determine that all necessary repairs have been made until fsck completes and gives its final report.
* The -f flag: Forces fsck to check "clean" filesystems when preening.
See also
* Handling "overlapped extent allocation" errors reported by Disk Utility or fsck
* Disk Utility reports "Underlying task reported failure" when repairing a volume
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