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#5803 - 11/13/09 10:25 AM Remove HD partition
Douglas Online


Registered: 08/04/09
Loc: Seattle, WA
I have a LaCie Mini external HD that has 2 partitions. I would like to remove the partition and just use the whole HD. Will be using it to clone my current Mini so its ok to erase and reformat if necessary.

What's the best way to do this?

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#5805 - 11/13/09 12:40 PM Re: Remove HD partition [Re: Douglas]
jchuzi Online


Registered: 08/04/09
Loc: New York State
Launch Disk Utility and select the LaCie in the DU window. Then, click the Erase tab. It would be advisable to click Security Options and opt to zero out data before clicking the Erase button. This takes longer than simple erase but will map out bad blocks. In the process, you will create one partition and then be able to clone your Mini to it.

BTW, the desired format is Mac OS Extended (journaled) but this should be selected by default.

For comparison purposes only, I used the zero out data option to erase an internal drive (120 GB) in my Powermac G4 DP 450 and it took about 40 minutes. Your time will vary.
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OS 10.14.6, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365

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#5806 - 11/13/09 03:16 PM Re: Remove HD partition [Re: jchuzi]
Douglas Online


Registered: 08/04/09
Loc: Seattle, WA
Thank you

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#5836 - 11/15/09 02:32 PM Re: Remove HD partition [Re: Douglas]
Shefftini Offline


Registered: 08/22/09
If the drive was GPT formatted you might get away with just removing the partition with Disk Utility. With 10.4.6 and beyond the addition, resizing, and deletion of partitions became a reality with OS X. No loss of data if done carefully. Some restrictions re USB/Firewire and versioning of Disk Utility.

Since you are willing to lose data a simple repartition would do the job. If you use Options to make the basic format GPT you will have a lot of options in the future.

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#5844 - 11/15/09 04:05 PM Re: Remove HD partition [Re: Douglas]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
If you just want it done quick, open DU with the drive attached. Select the drive (not either of the two partitions below it) and select the Partition tab. Change 'two partitions' to 'one partition'. Give it a name other than Untitled. I always click Options to make sure its going to use the partition scheme I want. Intels boot from GUID/GPT, powerpc can only boot from APS. Close that window and click Partition. OK the warning and let it run. Should take about 15 seconds.

I don't use the Erase tab because you don't have the option to change the partition table type, and sometimes it's set wrong, so I just make a habit of always checking. I also format drives from other computers, and sometimes I have to for example format a HD in a macbook pro, from a G5, which will want to format it APS (goes by what's booted, not what's currently on the HD!) so I need to make sure I'm checking every time.

As above, if the partition scheme is correct you can probably get away with simply deleting the unwanted partition. This usually is pretty fast, maybe 20-50 seconds. SPLITTING a partition however, can be a very lengthy (hour+) affair if it has to move a lot of data into the smaller section before splitting it.
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#5860 - 11/16/09 01:25 AM Re: Remove HD partition [Re: Virtual1]
ryck Online


Registered: 08/04/09
Loc: Okanagan Valley
[quote=Virtual1Select the drive (not either of the two partitions below it)[/quote]

So THAT'S what those extra drive images are. I have a very simple set up without partitions and always wondered why I'd see them.

So, question....if I'm performing a preventive maintenance function (e.g. DU Repair Disk), and am not partitioned, is there any advantage of using one image over the other?

ryck


Edited by ryck (11/16/09 01:25 AM)
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#5871 - 11/16/09 03:52 PM Re: Remove HD partition [Re: ryck]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
image of what?
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#5873 - 11/16/09 04:25 PM Re: Remove HD partition [Re: ryck]
dkmarsh Offline
Moderator

Registered: 08/04/09

Technically, even an "unpartitioned" disk has a single partition. When you look at the left-hand column in the Disk Utility window, booted from a single-partition internal drive with no external drives connected, you'll see two entries, the bottom one indented relative to the top one.

The top entry is the physical device. The indented entry below, which bears the name of your boot drive, is the logical volume, which—as you'll see if you compare the Capacity when it's selected with the Total Capacity when the physical device is selected—isn't quite as big. (In my case, a 37.3 GB drive contains a single 37.1 GB partition.)

The discrepancy is accounted for by the space occupied by the the disk directory—the structure which "defines" the logical volume (slightly like the way the exterior walls define a house, even one with a single room, and in so doing eat up a little of the overall footprint).

Running Repair Disk with the physical device selected simply runs Repair Disk in turn on each logical volume (partition) contained on that device. If you have only a single partition, there's no difference betweeen the two. (Of course, when you're booted from your internal drive, you can't Repair Disk on it anyway, but that's what the case would be if you were booted from, say, your installation disc.)
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#5875 - 11/16/09 05:28 PM Re: Remove HD partition [Re: dkmarsh]
ryck Online


Registered: 08/04/09
Loc: Okanagan Valley
Thanks. Good to know.

ryck
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ryck

iMac (Retina 5K, 27", 2017), 3.4 GHz Intel Core i5, 8GB RAM, 2400 MHz DDR4
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Canon MX710 Printer
Epson Perfection V500 Photo Scanner
Carbon Copy Clone on 1TB LaCie USB-C
Carbon Copy Clone on 500GB OWC Mercury OTG Pro

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#5879 - 11/17/09 08:28 AM Re: Remove HD partition [Re: dkmarsh]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
Original single partition systems however did not have a partition table. The only partition just simply started at the first block on the drive. MS DOS partitions iirc still can work that way. Apple hasn't done that for a VERY long time.

Also OS 9 and earlier required drivers on the device, often around 9 separate partitions. These are not data partitions, and do not show up as partitions in disk utility, but if you use diskutil in terminal you can easily see them. So many OS 9 drives actually had around 10 partitions in their table, nine of which were drivers. Why so many drivers? I think they were for all the various kinds of drives such as scsi, jazz, etc, and OS 9 just put all the drivers on every time for simplicity's sake. The drivers were quite small, under 260k each typically.

Code:
localhost:~ virtual1 $ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *465.8 Gi   disk0
   1:                        EFI                         200.0 Mi   disk0s1
   2:                  Apple_HFS Macintosh HD            433.8 Gi   disk0s2
   3:       Microsoft Basic Data WINDOWS HD              30.7 Gi    disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *10.0 Gi    disk1
   1:                 Apple_HFSX virtual1                10.0 Gi    disk1s2
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *465.8 Gi   disk2
   1:        Apple_partition_map                         31.5 Ki    disk2s1
   2:             Apple_Driver43                         28.0 Ki    disk2s2
   3:             Apple_Driver43                         28.0 Ki    disk2s3
   4:           Apple_Driver_ATA                         28.0 Ki    disk2s4
   5:           Apple_Driver_ATA                         28.0 Ki    disk2s5
   6:             Apple_FWDriver                         256.0 Ki   disk2s6
   7:         Apple_Driver_IOKit                         256.0 Ki   disk2s7
   8:              Apple_Patches                         256.0 Ki   disk2s8
   9:                  Apple_HFS Service Classic         895.9 Mi   disk2s10
  10:                  Apple_HFS Service Tiger           11.4 Gi    disk2s12
  11:                  Apple_HFS Service Leopard         24.4 Gi    disk2s14
  12:                  Apple_HFS Mac OS 9.2.1            895.9 Mi   disk2s16
  13:                  Apple_HFS Mac OS 10.3.4           895.9 Mi   disk2s18
  14:                  Apple_HFS Mac OS 10.3.4 Disc 2    895.9 Mi   disk2s20
  15:                  Apple_HFS Mac OS 10.4.6           3.4 Gi     disk2s22
  16:                  Apple_HFS Mac OS 10.5.6           7.9 Gi     disk2s24
  17:                  Apple_HFS Mac OS 10.4.7           6.4 Gi     disk2s26
  18:                  Apple_HFS Mac OS 10.6.0           9.4 Gi     disk2s28
  19:                  Apple_HFS Service Snow            13.4 Gi    disk2s30
  20:                  Apple_HFS Service Data            384.6 Gi   disk2s32



That third drive is OS 9 bootable and you can see all the drivers at the top. It shows up as 12 (data) volumes on the desktop and disk utility.

And if you really want to split hairs, the partition table itself is a partition, that describes the entire drive.
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#5926 - 11/18/09 11:28 PM Re: Remove HD partition [Re: jchuzi]
artie505 Online


Registered: 08/04/09
> It would be advisable to click Security Options and opt to zero out data before clicking the Erase button. This takes longer than simple erase but will map out bad blocks.

In view of

Quote:
We find, for example, that after their first scan error, drives are 39 times more likely to fail within 60 days than drives with no such errors.

and

Quote:
Despite those strong correlations, we find that
failure prediction models based on SMART parameters
alone are likely to be severely limited in their prediction
accuracy, given that a large fraction of our failed drives
have shown no SMART error signals whatsoever.

from Google's "Failure Trends in a Large Disk Drive Population," don't you think it would be wise to advise posters to run a surface scan before zeroing all data?

Mapping out a bad block you don't know is there leaves you at far greater risk of a catastrophic issue than does leaving it intact.
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#5937 - 11/19/09 03:33 AM Re: Remove HD partition [Re: artie505]
jchuzi Online


Registered: 08/04/09
Loc: New York State
Good points, Artie.
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#5942 - 11/19/09 07:50 AM Re: Remove HD partition [Re: artie505]
alternaut Offline

Moderator

Registered: 08/04/09
Originally Posted By: artie505
Mapping out a bad block you don't know is there leaves you at far greater risk of a catastrophic issue than does leaving it intact.

Hmm, are you saying that the simple act of checking if there is a problem (with a utility other than SMART) is worse than actually having one? shocked If you actually mean that the remapping process causes the problem, I suspect you're putting the horse behind the cart: one's a symptom, the other a cause.
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#5959 - 11/19/09 06:34 PM Re: Remove HD partition [Re: alternaut]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
I would say SMART is a better way of confirming a problem than relying on it to catch one.

I've seen many hard drives fail in my time. I just hauled off a box of about 130. It's been my observation that SMART is the first sign in about 2% of cases. The entire remainder I would split about 65/35 with sudden death being 65% (click click click) and slow performance being 35%. Of those 65% however, had they been checking io speeds I strongly suspect they'd have received advance warning before total failure. A lot of people say their computer was being sluggish recently and I assume that was it. So it's possible that the "slow io" warning occurs as much as 80% of the time before a catastrophic failure.

In almost every case of slow IO being the symptom of suspicion, when I check them their SMART is passing. Then I surface scan them with that nugget I posted earlier, and see the slow IO. Sometimes then I start seeing it get worse, and start producing io errors. At that point, about 20% of drives smart toggles to FAIL, the other 80% remains PASS until they suddenly start timing out or fail altogether and are a real pain to get anything off from.

Needless to say, I don't give SMART any kudos. It's a nice idea, but I just don't understand why the slow IO doesn't trip a flag, but it never seems to. And it's almost always a critical warning. I've only seen two drives in all my time that had slow io in a range and continued to run otherwise reliably for more than a couple weeks.

I am currently running a rather primitive script on the servers here that does a slow background incremental scan on all attached volumes, insuring a complete read pass on all attached drives at least once per month. (DRIVES, not VOLUMES, it watches both slices of a mirror) If anyone is interested in playing with it let me know. It's designed for machines that run 24/7 and have at least one large volume that needs to be kept an eye on. Known to work on servers with up to 7+ TB of drives. Very spartain interface (bash) but emails warnings. It tagged a failing 1TB a month ago here that turned out to be a failing bridge board in the enclosure. Had the replacement drive in hand the day it failed to remount. smile
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#5960 - 11/19/09 06:42 PM Re: Remove HD partition [Re: alternaut]
Virtual1 Offline


Registered: 08/04/09
Loc: Iowa
as far as the remapping issue goes, remapping is a nice idea for isolated issues. A single block becoming unreliable and gets remapped, I'm ok with that. But when it's remapped hundreds of blocks I want to hear about it. Most SMART track remaps, and are set at some reasonable limit (usually around 100) before toggling SMART general status.

Problem is that bad blocks were common 10 or even 6 years ago, and are rather uncommon nowadays. Total failure however I think has gotten more common, and that's not something SMART is likely to be able to give you advance notice on. I think SMART in general is outdated in that respect. The slow IO that I look for indicates a general drop in performance, that signals impending critical hardware failure. (head, arm stepper, etc)

If they were truly smart, (hah, punny) they'd incorporate the scan that my script does, and run a slow periodic read scan while the drive was idle. THAT would be a lot more likely to find problems.
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#5967 - 11/19/09 10:19 PM Re: Remove HD partition [Re: Virtual1]
Hal Itosis Offline


Registered: 09/03/09
Loc: 10.6.8 (build 10K549)
Originally Posted By: Virtual1
Total failure however I think has gotten more common, and that's not something SMART is likely to be able to give you advance notice on. I think SMART in general is outdated in that respect. The slow IO that I look for indicates a general drop in performance, that signals impending critical hardware failure. (head, arm stepper, etc)

There's a very accessible (no geekage required) piece of freeware called smartctl menu which puts a lot of info on the menubar. The last item is 'quit' so it can be removed cleanly. It displays all the S.M.A.R.T. values (including the much disputed Seek_Error_Rate and Load_Cycle_Count items). I realize there's no 'precise' threshold which holds true for all models and manufacturers... but maybe a user taking occasional peeks at that info on their own HD can espy a noticeable change one day (or something).

smartctl doesn't pretend to be a predictor of failure (i don't think so anyway), but it does at least show us what all measurements exist easily enough (in a free package based on the smartmon tool suite).

--

[might want to check the FTM server's HD... this session ran slow as molasses. wink ]


Edited by Hal Itosis (11/19/09 10:24 PM)

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#5977 - 11/20/09 03:30 AM Re: Remove HD partition [Re: alternaut]
artie505 Online


Registered: 08/04/09
Quote:
Mapping out a bad block you don't know is there leaves you at far greater risk of a catastrophic issue than does leaving it intact.

> Hmm, are you saying that the simple act of checking if there is a problem (with a utility other than SMART) is worse than actually having one?

I said nothing about checking for anything with anything; if OS X's "zero all data" functionality checked for and spotlighted bad blocks rather than blindly obscuring them there'd have been no reason to post.

What I said is that remapping causes a problem in that (in view of the Google report) mapping out a bad block you don't know is there leaves you ignorant of your risk of (perhaps) imminent catastrophic HD failure while leaving the block intact leaves you with the possibility of tripping over it and being in a better position to possibly recover your data before your HD goes irredeemably south.


Edited by artie505 (11/20/09 04:02 AM)
Edit Reason: Changed "remapping" to "OS X's 'zero all data' functionality"
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#5985 - 11/20/09 05:45 AM Re: Remove HD partition [Re: Hal Itosis]
artie505 Online


Registered: 08/04/09
> smartctl doesn't pretend to be a predictor of failure (i don't think so anyway), but it does at least show us what all measurements exist easily enough (in a free package based on the smartmon tool suite).

Great!

Thanks for mentioning it. smile
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The new Great Equalizer is the SEND button.

In Memory Of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire

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Moderator:  alternaut, cyn