Volume Erase failed with the error: Could not modify partition map

ashta wrote:

Eeeek. It got stuck trying to install and said 35 minutes remaining. I thought it was stuck so I moved the mouse in front of the blue bar and let it sit there for ~10 minutes. It never changed position, so I restarted and cancelled the installation. I just started a new one up. Here is the log from when it got stuck :/.

Err.. computers really don't like me right now. Now the windows desktop wont recogonize my usb drive when I plug it in to copy the log over.. I don't think I can get any more logs until I figure this out too...

You should have let it complete or run overnight to make sure, sometimes the installer doesn't update as often and it apears to be stuck. If your prematurely canceling the install, perhaps that's why your getting the log files?

If not, perhaps you have a bad disk or a hardware issue with the Mac. 😟

Looks like your going to need a external powered hard drive to install 10.6 (then option boot) to determine if it's your internal hard drive or the disk.

Perhaps the disk is scratched, that occurs if it's not taken extreme care of and just laid around.

If the drive was Zeroed there is basically nothing on it to cause problems from bad sectors, unless you ran out of spares 😮

So now it's got to be the disk as that's where all the data is coming from, the optical drive, hard drive or another issue.

The disk is easiest and least expensive to replace, only $29.

Oh, well we gave it our best shot, good luck. anyhow. 🙂

ds store wrote:

I invite you to read what Dr. Smoke (a long time ACS forum contributor) has to say about bad sectors.

With all due respect for Dr. Smoke, the info he provides about the zero data erase finding bad blocks is misleading & badly out of date. In all modern drives, the drive itself, not Disk Utility, detects bad blocks, & it can do so only on reads. This is an inherent physical limitation: the drive's heads can either write data or read it, but not do both at the same time. There is no way to determine if the sector has retained the data applied to it during a write besides reading it back, which requires a second pass over the sector with the head in read mode.

So when he says, "When an attempt to write zeros to bad sectors fails," he is assuming the drive reads what it has just written on a second pass, since there is no other way to know if the write failed or not.

Long ago, drives always did this, unless the feature was specifically disabled. If you used SCSI drives for video capture work in the late 1980's or early 1990's, you may have learned how to access their mode pages to turn off read verification (sometimes known as "RAW," or read-after-write) to 'tune' the slow drives of that era to be fast enough to capture a live video stream.

However, modern ATA & SATA drives do not give you this option, & if they do read-after-writes at all, they do so only during the first few hours of operation, after which that is automatically switched off to improve performance. This is why sites like BareFeats always "break in" new drives before benchmarking them. If they did not, the benchmarks might be performed with read-after-write enabled, approximately halving the scores of new drives vs. ones that have been in use for a while.

So, while the zero erase might cause a brand new drive (or a vintage one) to map out bad sectors, this isn't true in the general case.

If you don't believe this, you can test it for yourself: get the drive's specifications for read & write times, from that calculate how long it would take for the drive to do a read verification of all the sectors in the partition after zeros are written to them, & compare that time to how long the zero erase actually takes. In most cases you will find that it is actually substantially less than half as long as that would take because the drive is actually doing a fast block fill provided for this purpose in the ATA command set.

ashta wrote:

I verified that partition just now, and it said that it was fine (Using verify button). Then I used the repair button, and it gave me an "Error could not unmount disc".

Then I tried to manually unmount it using the unmount button, and it still said it could not unmount it.

Make sure that you are both booted from the installer DVD & running its copy of Disk Utility (from the Utilities menu) when you try the repair, & double-check that you are trying to repair your newly formatted partition & not some other "disk" (for instance, the DVD itself).

R,

Disk Utility is reading the drive to confirm it's securely written zeros, thus enabling the drive to perform it's function and map off bad sectors.

If what you say is true that data is being written with no read confirmation, then that just validates the zero-fill need before large writes across many sectors, which something as important as a OS install certainly qualifies.

Also if what you say is true about only a few first hours of a drives life there is read confimation/"breaking in", that is obviously for factory installs when the computer is first assembled where more reliability for OS installs is required.

How the consumer got screwed over for reliable installs of operating systems is beyond me, we have to perform a zero fill "hack" or gamble on not writing to a bad sector.

ds store wrote:

Disk Utility is reading the drive to confirm it's securely written zeros, thus enabling the drive to perform it's function and map off bad sectors.

There is no evidence that this is true. Again, get the specs for your drive, figure out how long a read of all the sectors would take, & compare that to how long Disk Utility's secure erase takes. If the secure erase takes less than that much time, it is impossible that it is doing a read after write.

If what you say is true that data is being written with no read confirmation, then that just validates the zero-fill need before large writes across many sectors, which something as important as a OS install certainly qualifies.

That makes no sense. You are saying if something doesn't do something, do it again so that it will.

Also if what you say is true about only a few first hours of a drives life there is read confimation/"breaking in", that is obviously for factory installs when the computer is first assembled where more reliability for OS installs is required.

Actually, it is to catch "infant mortality" type issues that might occur after the unit is shipped to users. Sectors can go bad at any time but are most likely to at the beginning & end of its useful life.

How the consumer got screwed over for reliable installs of operating systems is beyond me, we have to perform a zero fill "hack" or gamble on not writing to a bad sector.

You only have to gamble that the drive won't detect a sector going bad on a read & map it out automatically after moving the data to a good sector, which the drive does whether or not you perform any so-called hack:

Every time the drive reads from (not writes to) a sector, it verifies its integrity via data checksums & by monitoring the signal characteristics coming from the head. It is actually not that uncommon to get a read error that requires a retry to get good data in a modern high density drive. (That's part of the reason average read time specs are longer than write ones, in case you were wondering about that.) The drive tracks how often a sector requires a retry & if it exceeds a threshold determined by the drive's logic, it moves the data & spares out the sector.

There is nothing users have to do for this to occur. It is entirely automatic -- in fact, if it were not modern drives would not store data reliably.

Welcome back ashta,

I want to apologize for the interuption, it's not polite to disrupt your thread.

We Level 6+'s have a whole Lounge to ourselves to discuss our litle debate and it's ended up the same way, it shouldn't have come here.

ashta wrote:

Only... now I have a new problem. It is super slow. I get the circle/rainbow beachball all the time and it takes 3-5 minutes to boot up and start into my web browser. I loved how before it was broken it only took 30-70 seconds to log in and get a browser or word open.

I guess I can live with the slower boot times.. but the beachballs/somtimes-lag-between-clicks-and-action-appearing are super annoying and I don't want to be dealing with them at all. They never happened before on Lion. 😟.

ashta,

Something is wrong with your hardware, even though you might have gotten OS X on it, those 3-5 minutes to boot is excessive, it should only take under a minute.

I suspect your drive is failing and will need to be replaced.

And thank you for the serial number. I have written it down, and placed it inside the box incase I ever need it. 🙂.

Good. 🙂

Err.. and Don't worry about the alchol thing. I used water on a damp piece of toilet paper since I couldn't find any rubbing alchol. (I felt that toilet paper was softer than a cloth).

Sounds good. Long as the bottom is polished and free of smudges/residue that deflect the laser beam.

And you guys can continue to debate the harddrive thing too, even though it isn't important anymore .

Like I said, this was the wrong thread to discuss that issue and confuse resolving your issue.

Since that problem is solved now?

Your problem is not resolved, 3-5 minutes to boot is certainly some sort of hardware issue and will only conk out on you later on.

Boot time from "bong" to desktop, minus the login time, with no programs auto-launching, no internet access, should be about 30-60 seconds.

I'm afraid despite your gallant effort and a bit of hacking, your drive or something else is at fault.

I wish you could install 10.6 onto a external drive and hold the option key and boot from it, that right there will tell you quite a bit, especially if it's your internal drive or cable.

So you've got this far, you'll have to decide if you can go any further. 🙂

ashta wrote:

Do I just take it to an apple store to replace it? :/

You can try, some will do it and others won't, if your under warranty/AppleCare then they will do it for free, but you don't get anything better in storage or speed usually.

However a local PC/Mac person can, if your out of warranty/applecare plus you can tell them what you want installed. Will of course cost money.

Or if your handy, you can do it yourself and order the drive online.

I'd advise a 500GB -1TB 7,200 RPM drive, you'll get more storage and speed too.

Otherworld Computing is advised, they have videos here

http://eshop.macsales.com/installvideos/

ashta wrote:

I might be able to borrow am external hd if I ask on facebook. Would their data ever somehow be deleted (by accident, or on purpose to backup)

If you borrow a external hard drive it will need to be free of data they want to keep because to format it your going to be erasing it.

If they have no problem with you formating/erasing the data on it, then that's ok. But I would get it in writting becuase they may change their mind and say you erased the data on purpose.