Should partition sizes be powers of 2 ?

Tony0945 · Posted: Fri Jan 15, 2021 7:16 pm Post subject:

figueroa,

That 2011 BIOS is the latest available. Although seeing how the board is dual BIOS, maybe I could change the BIOS jumper.
I want to remove the sda drive as it is damaged and can't complete a smart control check. I suppose I could boot off of sdb and just replace sda with a similar drive.
I haven't thought of that before.

NeddySeagoon · Posted: Fri Jan 15, 2021 10:42 pm Post subject:

Tony0945,

Can't you boot from a floppy any more :)
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Tony0945 · Posted: Fri Jan 15, 2021 11:58 pm Post subject:

Tony0945 · Posted: Wed Jan 20, 2021 11:05 pm Post subject:

Got the drive assembled and into the computer. well, actually, the side is off and parts are strewn around, but i got it recognzing all the drives and in the right order.

I've started copying the partitions but something doesn't look right. I must have hit keys wrong?

Tony0945 · Posted: Wed Jan 20, 2021 11:27 pm Post subject:

Also parted

Tony0945 · Posted: Thu Jan 21, 2021 12:29 am Post subject:

Googled and used parted, x for advanced and f for fix. Looks right now.

NeddySeagoon · Posted: Thu Jan 21, 2021 12:45 am Post subject:

Tony0945,

The partition numbers don't matter. The sizes matter a lot. If the data is in the correct sized partitions, you can leave it in a mess.

If the table ordering really matters, you can change it without losing any data.
A partition table is a set of pointers to data. Removing the pointers does not remove the data, it just makes it difficult to get at.

Make a note of the numbers ...

Tony0945 · Posted: Thu Jan 21, 2021 2:23 am Post subject:

All partitions are ext4 so using labels from "e2label" in the /etc/fstab of each bootable partition.
So the grub entries should be PARTUUID if I understand you correctly. Or will labels do?

The last three partitions have copied. rsync just hung, so I mounted all the new partitions as /mnt/partN N=2,3,4 and used "cp -aur"

Now going to sign off, boot into the rescue partition and copy the main gentoo install into partition 1.
Then I'll have to:
1. edit all the /etc/fstab's using labels as noted
2. remove the SSD and carry it to a different machine. (It's actually sticking out with only the data and power cables attached.
3. Stick it in another machne, disconnect other dives to ensure it's /dev/sda. Candidate machines have bootable cdrom drives making it easier
4. boot sysrescuecd, chroot into partition1
5. run grub-install
6. for each of the other three partitions, chroot into them and install grublegacy or grub2 as appropriate
7. take the SSD out and transfer it back to the original machine.
The physical parts may be tough. It took me 15 minutes or so to get SSD mounted with the power cable correctly. Eyes are real bad today. Would up using a SATA power splitter which worked well. The existing SATA power cable has three connecters but they are short and hard to work with. Stupid pride prevented me from asking my wife to connect them.

Until tomorrow!

Tony0945 · Posted: Thu Jan 21, 2021 5:29 pm Post subject:

Wasted the morning stubbornly trying to get the USB usbstick to boot. Also tried running grub-install on the SSD in it's /dev/sdc position.
Then disconnected the other SATA connecters and rebooted. Endless scrolling of "GRUB Stage 1.5" message.
Along the way, I discovered that the mobo does support EFI. They just don't call it that. Tempted to scrap everything, reformat as gpt, and install r3efind. But I need a UEFI boot medium to do that. So, it's setup grub on another machine, or obtain another CD-ROM drive, possibly by disassembling a working machine. I used to have a portable CD drive from my sister's laptop. it vibrated too much to write reliably but might boot.

J

Tony0945 · Posted: Fri Jan 22, 2021 11:47 pm Post subject:

After the day long odyssey to restore my second system (see https://forums.gentoo.org/viewtopic-p-8563972.html#8563972). I've ordered a new DVD drive for this system.

szatox · Advocate Joined: 27 Aug 2013 Posts: 3203

NeddySeagoon · Posted: Sat Jan 23, 2021 12:42 pm Post subject:

Tony0945,

You can do an in place MSDOS to GPT migration without losing anything. There might even be a tool for it, I didn't search.
First some background, so you understand what you are getting into.

The MSDOS partition table has the primary partitions in the last 66 bytes of LBA 0.
If you have and extended partition, that reserves space and points to the first entry in a linked list that defines the logical partitions.
Each logical partition contains a pointer to the next logical partition, if there is one. Hence when you delete partition 5, all the rest move down one.

GPT has a 'protective, MSDOS partition table in LBA 0 then the first copy of the GPT follows. It occupies LBA 1 to 2047. Hence partitioning tools default to starting the first partition at LBA 2048.
So you have space for the first copy of the GPT before the first partition.
GPT keeps a second copy at the end of the block device too. That's unfortunate as with MSDOS in use you will likely have a filesystem there.

The method then, is to shrink the filesystem at the physical end of the device to make room for the backup copy of the GPT.
Copy the sector numbers from the existing MSDOS partition table.
Write a new GPT disk label. If you missed the filesystem shrink, this step will trash that filesystem.
Put the old partition boundaries back. Including the extended partition if there was one.
WARNING:the physically last partition on the device is now about 2048 blocks smaller as the space has been taken up by the GPT copy, so make the partition as big as you can.
Everything should just work but you did make a backup before you started, didn't you?

Grow the final filesystem to fit the space in its new home.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Tony0945 · Posted: Mon Jan 25, 2021 2:31 am Post subject:

Yes, NeddySeagoon, I could do that. There is plenty of room to shrink the last partition. But copying from the existing HDD was easy, just took time. I'd probably be better off re-partitioning it totally and putting a swap partition back. while editing the fstab's I see that the 32bit partition and the RESCUE partition use the existing swap device. Not sure about the Ubuntu partition. it might be best to just re0install Ubuntu anyway. I have no files there. My main Gentoo partition used both the external swap partition and a 12G swapfile, so deleting the swap partition was no problem. I could do that for the rescue partition also. Not sure about the 32bit partition. It should have swap as it's a build box for the k6 machine. The PC has 8G RAM with all slots full. But the 32bit install can only see half of it. 4G is not enough for some packages.

My new CD drive came yesterday. Now to find time to install it.

timeBandit · Posted: Tue Jan 26, 2021 7:31 pm Post subject:

Out of curiosity: Why allocate so much space to the rescue partition? For something that's truly for emergency use only, 145GB seems awfully chunky. I'd bet there's another 100GB there for the taking, to allocate to your other partitions, without (I would think) seriously compromising rescue functionality.

For any binary distro I wouldn't have thought twice but you did say, it's a Gentoo rescue partition. So why not make it lean and mean?

To illustrate, my small home server--with Apache, Postfix+Dovecot, a bare-bones DLNA server, a minimal Xfce desktop, and more besides--has an installed footprint of ~13GB, about 20% overall utilization of the system partitions. (Data reside on a separate, much larger HDD). Granted, this is a 32-bit system, and perhaps unattainably compact in a 64-bit world. I'd still bet 50% utilization of a 40-50GB partition is attainable with a solid collection of fix-my-system tools and a trim-but-useful desktop environment...and there's your 100GB.

Of course, "not worth the trouble to prune it" is a perfectly valid choice, too.

_________________
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Tony0945 · Posted: Tue Jan 26, 2021 8:13 pm Post subject:

Tony0945 · Posted: Wed Jan 27, 2021 8:34 pm Post subject:

All right! halfway home. I procured a new CDROM drive and still couldn't boot it. Tried setting BIOS from EFI MODE -Auto to EFI MODE - Bios. Not go.
Eventually found that setting SATA ports 4/5 to IDE instead of SATA (even though drive IS SATA) worked to get me into sysresecue CD.

From there, I chrooted into /devsda1 and ran "grub-install /dev/sda" (grub legacy is installed), then rebooted.
Success! (I thought). My familiar grub menu appeared. but when I selected the first entry, it failed to load with, I think, "can't find root device".
Right now I'm in the chroot, the only drives are the SSD at SATA port 0 and the LITE-ON CD drive at SATA port 4

Tony0945 · Posted: Wed Jan 27, 2021 10:38 pm Post subject:

PARTUUID didn't work either. this time I wrote the error message down.

"ERROR 15: File not found." I think it's a grub message.

I chrooted into the 32bit partition using linux32. I re-installed grub-legacy with "grub-install /dev/sda2". It failed to chain load with the same ERROR 15.

NeddySeagoon · kernel /boot//vmlinuz-5.4.72-gentoo

Tony0945,

Tony0945 · kernel /boot//vmlinuz-5.4.72-gentoo

Tony0945 · Posted: Thu Jan 28, 2021 2:04 am Post subject:

BTW, I did run "hdparm -tT /dev/sda" on the SSD when in the chroot. 532Mbps. Quite sweet! Fantastic to a guy that started with eight inch floppys on an Intel develpment system.

Tony0945 · Posted: Thu Jan 28, 2021 6:35 pm Post subject:

Up and running and booting on it's own!
Major problem with booting this morning. Would not boot from CD and could not open cd drive.
I unhooked every other drive and sysrescuecd 5.3.2 booted promptly. Threw away the old SATA cables.
BIOS still flaky about entering. Now chokes on DEL, halfway through listing devices. Still responds to F12 to select boot device. So I've left it at "Boot from CDROM first" If I don't have a bootable medium there, it switches to the first HDD. I'm thinking this BIOS need to be re-flashed but I'm not going to go there now.

Both grub legacy partitions are booting. The grub2 rescue partition was rescued by a procedure that I had to search for and put as a note in /boot/grub

NeddySeagoon · Posted: Thu Jan 28, 2021 7:17 pm Post subject:

Tony0945,

root (hd0,0) is grub speak for where to find the files that grub will load.
root= points tho the kernels root partition.

The two uses of the word root mean two different things.

It appears that's the hard bit done now that it boots on its own.

You can use the kernel command line

saellaven · l33t Joined: 23 Jul 2006 Posts: 648

saellaven · l33t Joined: 23 Jul 2006 Posts: 648

oh, and for a comparison to SSD on the same machine

Tony0945 · Posted: Thu Jan 28, 2021 8:06 pm Post subject:

saellaven,
Awesome speed. Awesome price!

542, 527. Pretty close. Velociraptor rotated nearly twice as fast as a standard hard disk.