Is it possible to turn an already installed system into RAID0?

C

cabriofahrer

I have FreeBSD amd64 10.3 already installed on a single SATA drive (ada0) and I have other spare drives for additional data storage:

Code: 
$ dmesg | grep ada
ada0 at ata2 bus 0 scbus2 target 0 lun 0
ada0: <SAMSUNG HD160JJ WU100-41> ATA-7 SATA 2.x device
ada0: Serial Number S08HJ1QL907862
ada0: 300.000MB/s transfers (SATA 2.x, UDMA5, PIO 8192bytes)
ada0: 152627MB (312581808 512 byte sectors)
ada0: Previously was known as ad4
ada1 at ata3 bus 0 scbus3 target 0 lun 0
ada1: <SAMSUNG HD160JJ WU100-41> ATA-7 SATA 2.x device
ada1: Serial Number S08HJ1QL907857
ada1: 300.000MB/s transfers (SATA 2.x, UDMA5, PIO 8192bytes)
ada1: 152627MB (312581808 512 byte sectors)
ada1: Previously was known as ad6
ada2 at ata4 bus 0 scbus4 target 0 lun 0
ada2: <SAMSUNG SP1614C SW100-30> ATA-7 SATA 1.x device
ada2: Serial Number 00000000000000
ada2: 150.000MB/s transfers (SATA 1.x, UDMA5, PIO 8192bytes)
ada2: 152627MB (312581808 512 byte sectors)
ada2: Previously was known as ad8
ada3 at ata5 bus 0 scbus5 target 0 lun 0
ada3: <ST3160827AS 3.42> ATA-6 SATA 1.x device
ada3: Serial Number 4MT0ADSG
ada3: 150.000MB/s transfers (SATA 1.x, UDMA5, PIO 8192bytes)
ada3: 152627MB (312581808 512 byte sectors)
ada3: Previously was known as ad10
Trying to mount root from ufs:/dev/ada0p2 [rw]...

Ada0 and ada1 are the same and could therefore become a RAID0 array together. Is it possible to "merge" ada0 and ada1 to a RAID0 without losing my installation following the steps of chapter 18.2 of the Handbook? And if not, how are you supposed to create a software RAID0 system with FreeBSD without using the hardware option in the BIOS prior to committing to the installation? Because one of the advantages of software RAID with FreeBSD is that you can have it even without a RAID controller, right?

Another question: would my ada2 and ada3 be compatible for a second RAID0, let's say, in another PC? Also there I would need to know how to proceed with a fresh installation in order to create a software RAID0? ZFS is not an option to me, as I only have 2 GB of RAM.
 
Thank you, but I still don't like the idea of ZFS and I would really like to stick to UFS.

kpa said:
Otherwise it's a better idea to backup the whole system and build the new disk layout
Click to expand...

Allright, but how exactly do I do this? I think bsdinstall does not offer that option? The partition tool would recognize the hard drives and alternatively offer ZFS. So how do I implement the gstripe(8) solution at the beginning of an installation process, so that FreeBSD gets installed onto that RAID0 system?
 
The easiest option for what you're attempting to do, is by way of geom(8) CONCAT. Some might argue that it's not the best route to take. But I can speak from experience, that this method served me well, for years without any issue -- very dependable. :) It's easy, too!

--Chris
 
Do you really mean RAID0? As in faster but twice as likely to fail as a single disk? If you just need more space, that's not necessary. Partition the extra drives and make separate filesystems on them. That can be done without having to move the existing system to a whole new device.
 
Thanks so far for giving other ideas about gaining disk space, but yes I would really like to do a fresh install on a RAID0 system with UFS.

Chris_H said:
The easiest option for what you're attempting to do, is by way of geom(8) CONCAT. Some might argue that it's not the best route to take. But I can speak from experience, that this method served me well, for years without any issue -- very dependable. :) It's easy, too!

--Chris
Click to expand...

Could you please elaborate? Exact steps? So far I know that in bsdinstall, when you get to the partitioning part you can select "shell". And I guess then I would have to do

gpart destroy -F ada0
gpart destroy -F ada1
gpart create -s gpt ada0
gpart create -s gpt ada1

And to create the stripe something like gstripe label st0 /dev/ada0 /dev/ada1 or rather gstripe label st0 /dev/ada0p1 /dev/ada1p1, so stripe a previously created slice? And see, this is where my lack of knowledge starts: I would also need a boot and a swap partition, right? But are these created on the stripe /dev/stripe/st0 or twice on ada0 and ada1 and then only the freebsd-ufs partitions are striped?

On the other hand chapter 18.2 of the FreeBSD Handbook suggests doing gstripe label -v st0 /dev/ada0 /dev/ada1 on "unpartitioned" disks and then bsdlabel -wB /dev/stripe/st0, but wouldn't that be dangerously dedicated? It is all so confusing, so could someone please explain the exact steps/commands necessary to install FreeBSD onto a UFS-RAID0 stripe?
 
I also see an example that seems relevant in the gconcat(8) manual.

I have been meaning to try this out myself as I prefer UFS for simplicity and SSD durability seems quite high these days.

I would eliminate swap partition myself. I also think /boot can be a directory on your stripe with MBR.
 
Phishfry said:
I also think /boot can be a directory on your stripe with MBR.
Click to expand...

I am not so sure about that. Can you really create a freebsd-boot partition on a stripe, or would it not rather be necessary to have the freebsd-boot partition on a real device like ada0, so that the computer will be able to bootstrap at all, load the geom_stripe.ko module, as would be specified in /boot/loader.conf, to the be able to load the stripe, as would be specified in /etc/fstab?
 
Trying to do this with 160GB hard disk drives is not good. They are like 9 years old.

I am not sure gstripe(8) is directly bootable.(thank you WB@)

I have dual bay possible in my notebook. May just have to try.
RootOnZFS is the most common implementation of root on raid from my reading.
https://wiki.freebsd.org/RootOnZFS
 
You must log in or register to reply here.
Back
Top