Replacing the B3 boot hard drive

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asparak
Posts: 173
Joined: 08 Jun 2009, 07:38

Replacing the B3 boot hard drive

Post by asparak » 20 Feb 2015, 10:34

Hi all,

It's time to do a routine replacement of my boot hard drive and I'm also planning to upgrade the capacity at the same time. Anything special I need to look out for, or can I just disk clone and go for it?

Thanks

Asparak

Gordon
Posts: 1373
Joined: 10 Aug 2011, 03:18

Re: Replacing the B3 boot hard drive

Post by Gordon » 22 Feb 2015, 09:35

Verify that your U-Boot version is at least 2010.06. A 3TB drive or larger won't work otherwise.

Code: Select all

strings /dev/mtd0 | grep "^U-Boot "

asparak
Posts: 173
Joined: 08 Jun 2009, 07:38

Re: Replacing the B3 boot hard drive

Post by asparak » 24 Feb 2015, 16:28

Thanks Gordon. Applied the patch last year when I changed the external drive disk. Confirmed U-Boot is 2010.06.

I'll get a new disk on order.

Thanks

Stryker
Posts: 56
Joined: 17 Oct 2013, 11:03

Re: Replacing the B3 boot hard drive

Post by Stryker » 27 Feb 2015, 20:18

I recommend manually repartitioning the disk, since the install-script included in the rescue-system does not care about correct alignment in regards to advanced format disks (4K-sectors) with GUID-Partition-Tables (GPT).
If you bought a disk with a capacity of 2TB or more, you will have to use 4K sectors (address-limitations, 2^32 * 512B = 2TiB ~ 2,2TB).

The problem is, that most modern (AF) disks are still emulating 512B sectors to the system, but use 4K internally.
So it can happen, that a logical block (LBA) of a partition with sector-size 4K does overlap two internal 4K-secotrs.
This leads to performance issues, since the disk-controller has to perform two writes to physical blocks for each logical block.

- How to manually install -
You can hook up your new disk to a regular (linux) system and create the necessary partitions, maybe even remove the lvm-layer and go for a regular ext4 for home.
root has to be ext3 though, ext4 is not recognized by the bootloader.

Manually "Installing" can be achieved simply by copying over the files from the old system. (Remember to preserve permissions and owner, "cp -a")
You should also check, whether /etc/fstab or the lvm referenced the disk UUIDs instead of their names in /dev/ and modify accordingly.

It's a bit of work, but might be worthwile. Also a nice excercise in linux-commandline-operation.

redw0001
Posts: 96
Joined: 07 Sep 2009, 14:03

Re: Replacing the B3 boot hard drive

Post by redw0001 » 28 Feb 2015, 01:55

For anyone considering an SSD same alignment issue exists, to get the best out of it 4K alignment needs to be taken care of.

stasheck
Posts: 107
Joined: 15 Jan 2014, 13:13

Re: Replacing the B3 boot hard drive

Post by stasheck » 10 Mar 2015, 09:47

Does it really make a difference for B3? Has anyone taken performance measures?

Modern disks can obtain speeds around 100 MBps, while B3 controller allows some 25-30 MBps...

stasheck
Posts: 107
Joined: 15 Jan 2014, 13:13

Re: Replacing the B3 boot hard drive

Post by stasheck » 09 May 2015, 06:06

Scratch my last comment.

With 3TB HGST NAS drive:
# hdparm -Tt /dev/sda

/dev/sda:
Timing cached reads: 592 MB in 2.00 seconds = 295.92 MB/sec
Timing buffered disk reads: 392 MB in 3.01 seconds = 130.20 MB/sec

So, controller is actually capable of quite high speed - the bottleneck is later, with the CPU, when we try to do something with this data.

Gordon
Posts: 1373
Joined: 10 Aug 2011, 03:18

Re: Replacing the B3 boot hard drive

Post by Gordon » 10 May 2015, 03:22

I actually did run an extensive data throughput test and there is in fact degrading of performance at some point. I wrote about it some time ago, probably in the first Gentoo topic :?:

The conclusion however is that there is no real benefit from really fast disks because there is some bottleneck elsewhere. You may however benefit from (really) large disks where you only use the first ~65% of its capacity. Shamefully, in the original Bubba OS the swap space is located at the very end of the disk and that does result in additional degrading of performance when swap is needed. On the 1TB green drive where I performed this test speed on the swap partition was probably only 1/10th of the speed I got on the root partition (using Bubba OS layout).

stasheck
Posts: 107
Joined: 15 Jan 2014, 13:13

Re: Replacing the B3 boot hard drive

Post by stasheck » 10 May 2015, 06:35

Good thing then that Arch by sakaki aims to create swap as second partition 8)

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