Re: [gentoo-user] RAID 1 on /boot
On Sat, February 22, 2014 06:27, Facundo Curti wrote: Hi all. I'm new in the list, this is my third message :) First at all, I need to say sorry if my english is not perfect. I speak spanish. I post here because gentoo-user-es it's middle dead, and it's a great chance to practice my english :) Now, the problem. First of all, there are plenty of people here who don't have English as a native language. Usually we manage. :) I'm going to get a new PC with a disc SSD 120GB and another HDD of 1TB. But in a coming future, I want to add 2 or more disks SSD. Mi idea now, is: Disk HHD: /dev/sda /dev/sda1 26GB /dev/sda2 90GB /dev/sda3 904GB Disk SSD: /dev/sdb /dev/sdb1 26GB /dev/sdb2 90GB /dev/sdb3 4GB And use /dev/sdb3 as swap. (I will add more with another SSD in future) /dev/sda3 mounted in /home/user/data (to save data unused) Why put the swap on the SSD? And a RAID 1 with: md0: sda1+sdb1/ md1: sda2+sdb2/home (sda1 and sda2 will be made with the flag: write-mostly. This is useful for disks slower). In a future, I'm going to add more SSD's on this RAID. My idea is the fastest I/O. Now. My problem/question is: Following the gentoo's dochttp://www.gentoo.org/doc/es/gentoo-x86+raid+lvm2-quickinstall.xml, it says I need to put the flag --metadata=0.9 on the RAID. My question is ¿This will make get off the performance?. metadata=0.9 might be necessary for the BIOS of your computer to see the /boot partition. If you use an initramfs, you can use any metadata you like for the root-partition. I only found this documenthttps://raid.wiki.kernel.org/index.php/RAID_superblock_formats#The_version-0.90_Superblock_Format. This says the difference, but nothing about performance and advantages/disadvantages. Another question is, ¿GRUB2 still unsupporting metadata 1.2? See reply from Canek. In case that metadata get off performance, and GRUB2 doesn't support this. ¿Anyone knows how can I fix this to use metadata 1.2? I don't partitioned more, because I saw this unnecessary. I just need to separate /home in case I need to format the system. But if I need to separate /boot to make it work, I don't have problems doing that. But of course, /boot also as RAID... /boot seperate as RAID-1 and metadata=0.9 and you are safe. ¿Somebody have any ideas to make it work? It is similar to what I do, except I don't have SSDs in my desktop. I have 2 partitions per disk: 1 : /boot (mirrored, raid-1) 2 : LVM (striped, raid-0) All other partitions (root, /usr, /home, ) are in the LVM. I use striping for performance reasons for files I currently work with. All important data is stored and backed up on a server. For this, an initramfs is required with support for mdraid and lvm. Thank you all. Bytes! ;) You're welcome and good luck. Please let us know what the performance is like when using the setup you are thinking off. -- Joost
Re: [gentoo-user] RAID 1 on /boot
On Sat, 22 February 2014, at 5:27 am, Facundo Curti facu.cu...@gmail.com wrote: ... I'm going to get a new PC with a disc SSD 120GB and another HDD of 1TB. But in a coming future, I want to add 2 or more disks SSD. Mi idea now, is: Disk HHD: /dev/sda /dev/sda1 26GB /dev/sda2 90GB /dev/sda3 904GB Disk SSD: /dev/sdb /dev/sdb1 26GB /dev/sdb2 90GB /dev/sdb3 4GB And use /dev/sdb3 as swap. (I will add more with another SSD in future) /dev/sda3 mounted in /home/user/data (to save data unused) And a RAID 1 with: md0: sda1+sdb1/ md1: sda2+sdb2/home (sda1 and sda2 will be made with the flag: write-mostly. This is useful for disks slower). In a future, I'm going to add more SSD's on this RAID. My idea is the fastest I/O. I think you're thinking along the right lines, but I'd use something dedicated to the job: • http://bcache.evilpiepirate.org • https://wiki.archlinux.org/index.php/Bcache Stroller.
Re: [gentoo-user] RAID 1 on /boot
On 22/02/2014 11:41, J. Roeleveld wrote: On Sat, February 22, 2014 06:27, Facundo Curti wrote: Hi all. I'm new in the list, this is my third message :) First at all, I need to say sorry if my english is not perfect. I speak spanish. I post here because gentoo-user-es it's middle dead, and it's a great chance to practice my english :) Now, the problem. First of all, there are plenty of people here who don't have English as a native language. Usually we manage. :) I'm going to get a new PC with a disc SSD 120GB and another HDD of 1TB. But in a coming future, I want to add 2 or more disks SSD. Mi idea now, is: Disk HHD: /dev/sda /dev/sda1 26GB /dev/sda2 90GB /dev/sda3 904GB Disk SSD: /dev/sdb /dev/sdb1 26GB /dev/sdb2 90GB /dev/sdb3 4GB And use /dev/sdb3 as swap. (I will add more with another SSD in future) /dev/sda3 mounted in /home/user/data (to save data unused) Why put the swap on the SSD? And a RAID 1 with: md0: sda1+sdb1/ md1: sda2+sdb2/home (sda1 and sda2 will be made with the flag: write-mostly. This is useful for disks slower). In a future, I'm going to add more SSD's on this RAID. My idea is the fastest I/O. Now. My problem/question is: Following the gentoo's dochttp://www.gentoo.org/doc/es/gentoo-x86+raid+lvm2-quickinstall.xml, it says I need to put the flag --metadata=0.9 on the RAID. My question is ¿This will make get off the performance?. It has no impact on performance. metadata=0.9 might be necessary for the BIOS of your computer to see the /boot partition. If you use an initramfs, you can use any metadata you like for the root-partition. The BIOS should not care at all as it is charged only with loading code from the MBR. However, if the intention is to use grub-0.97 then the array hosting the filesystem containing /boot should: * use RAID-1 * use the 0.90 superblock format That way, grub-0.97 can read the filesystem from either block device belonging to the array. Doing it any other way requires a bootloader that specifically understands md (such as grub2). There's also the neat trick of installing grub to all disks belonging to the array for bootloader redundancy. However, I'm not entirely sure that Code Listing 2.35 in the Gentoo doc is correct. Given that particular example, I would instead do it like this:- grub device (hd0) /dev/sda grub root (hd0,0) grub setup (hd0) grub device (hd0) /dev/sdb grub root (hd0,0) grub setup (hd0) The idea there is that, should it ever be necessary to boot from the second disk, the disk in question would be the one enumerated first by the BIOS (mapping to hd0 in grub). Therefore, grub should be installed in that context across all disks. It should not be allowed to boot from any given drive and subsequently try to access =(hd1). With grub2, it's a little easier because it is only necessary to run grub-install on each of the drives: # grub-install /dev/sda # grub-install /dev/sdb I only found this documenthttps://raid.wiki.kernel.org/index.php/RAID_superblock_formats#The_version-0.90_Superblock_Format. This says the difference, but nothing about performance and advantages/disadvantages. The 0.90 superblock format is subject to specific limitations that are clearly described by that page. For example, it is limited to 28 devices in an array, with each device being limited to 2TB in size. Also, the 0.90 format will cause issues in certain setups because of the way that it places its metadata at the end of the block device [1]. That said, the 0.90 format does allow for the kernel to construct the array without any intervention from userspace so it still has its uses. The 1.2 format positions the superblock 4KiB from the beginning of the device. Note that this has nothing at all to do with the data, which usually begins 1MiB in. If you run mdadm -E on a member of such an array, the offset will be reported as the Data Offset. For example: Data Offset : 2048 sectors So, it's not a matter of alignment. Rather, the advantage of the 1.2 format is that it leaves a little space for bootloader code e.g. in case you want to create an array from whole disks rather than disk partitions. None of this matters to me so I tend to stick to the 1.1 format. It wouldn't actually make any difference to my particular use case. Another question is, ¿GRUB2 still unsupporting metadata 1.2? See reply from Canek. In case that metadata get off performance, and GRUB2 doesn't support this. ¿Anyone knows how can I fix this to use metadata 1.2? I don't partitioned more, because I saw this unnecessary. I just need to separate /home in case I need to format the system. But if I need to separate /boot to make it work, I don't have problems doing that. But of course, /boot also as RAID... /boot seperate as RAID-1 and metadata=0.9 and you are safe. ¿Somebody have any ideas to make it work? It is similar to what I do, except I don't have SSDs in my desktop. I have
Re: [gentoo-user] RAID 1 on /boot
Thank you so much for the help! :) It was very useful. I just need wait my new PC, and try it *.* jeje. Bytes! ;)
Re: [gentoo-user] RAID 1 on /boot
Please let us know what the performance is like when using the setup you are thinking off. Of course. I will post these here :) 2014-02-22 16:13 GMT-03:00 Facundo Curti facu.cu...@gmail.com: Thank you so much for the help! :) It was very useful. I just need wait my new PC, and try it *.* jeje. Bytes! ;)
[gentoo-user] RAID 1 on /boot
Hi all. I'm new in the list, this is my third message :) First at all, I need to say sorry if my english is not perfect. I speak spanish. I post here because gentoo-user-es it's middle dead, and it's a great chance to practice my english :) Now, the problem. I'm going to get a new PC with a disc SSD 120GB and another HDD of 1TB. But in a coming future, I want to add 2 or more disks SSD. Mi idea now, is: Disk HHD: /dev/sda /dev/sda1 26GB /dev/sda2 90GB /dev/sda3 904GB Disk SSD: /dev/sdb /dev/sdb1 26GB /dev/sdb2 90GB /dev/sdb3 4GB And use /dev/sdb3 as swap. (I will add more with another SSD in future) /dev/sda3 mounted in /home/user/data (to save data unused) And a RAID 1 with: md0: sda1+sdb1/ md1: sda2+sdb2/home (sda1 and sda2 will be made with the flag: write-mostly. This is useful for disks slower). In a future, I'm going to add more SSD's on this RAID. My idea is the fastest I/O. Now. My problem/question is: Following the gentoo's dochttp://www.gentoo.org/doc/es/gentoo-x86+raid+lvm2-quickinstall.xml, it says I need to put the flag --metadata=0.9 on the RAID. My question is ¿This will make get off the performance?. I only found this documenthttps://raid.wiki.kernel.org/index.php/RAID_superblock_formats#The_version-0.90_Superblock_Format. This says the difference, but nothing about performance and advantages/disadvantages. Another question is, ¿GRUB2 still unsupporting metadata 1.2? In case that metadata get off performance, and GRUB2 doesn't support this. ¿Anyone knows how can I fix this to use metadata 1.2? I don't partitioned more, because I saw this unnecessary. I just need to separate /home in case I need to format the system. But if I need to separate /boot to make it work, I don't have problems doing that. But of course, /boot also as RAID... ¿Somebody have any ideas to make it work? Thank you all. Bytes! ;)
Re: [gentoo-user] RAID 1 on /boot
On Fri, Feb 21, 2014 at 11:27 PM, Facundo Curti facu.cu...@gmail.com wrote: Hi all. I'm new in the list, this is my third message :) First at all, I need to say sorry if my english is not perfect. I speak spanish. I post here because gentoo-user-es it's middle dead, and it's a great chance to practice my english :) Now, the problem. I'm going to get a new PC with a disc SSD 120GB and another HDD of 1TB. But in a coming future, I want to add 2 or more disks SSD. Mi idea now, is: Disk HHD: /dev/sda /dev/sda1 26GB /dev/sda2 90GB /dev/sda3 904GB Disk SSD: /dev/sdb /dev/sdb1 26GB /dev/sdb2 90GB /dev/sdb3 4GB And use /dev/sdb3 as swap. (I will add more with another SSD in future) /dev/sda3 mounted in /home/user/data (to save data unused) And a RAID 1 with: md0: sda1+sdb1/ md1: sda2+sdb2/home (sda1 and sda2 will be made with the flag: write-mostly. This is useful for disks slower). In a future, I'm going to add more SSD's on this RAID. My idea is the fastest I/O. Now. My problem/question is: Following the gentoo's doc, it says I need to put the flag --metadata=0.9 on the RAID. My question is ¿This will make get off the performance?. I only found this document. This says the difference, but nothing about performance and advantages/disadvantages. I don't know the performance differences, if any, but in my tests everything worked with the default metadata (1.2). Another question is, ¿GRUB2 still unsupporting metadata 1.2? No, GRUB2 supports it just fine. You just need to use the mdraid1x GRUB2 module. In case that metadata get off performance, and GRUB2 doesn't support this. ¿Anyone knows how can I fix this to use metadata 1.2? It's not necessary. I don't partitioned more, because I saw this unnecessary. I just need to separate /home in case I need to format the system. But if I need to separate /boot to make it work, I don't have problems doing that. It works fine; I tested it in a virtual machine (and I used systemd, but it should not be significantly different with OpenRC). You can check my steps in [1] and [2] (with LUKS support). But of course, /boot also as RAID... It works even with boot being on LVM over RAID. ¿Somebody have any ideas to make it work? I didn't tested in a real life machine (I've never been a fan of neither RAID nor LVM), but in a VM it worked without a hitch. Again, check [1] and [2]. Hope it helps. Regards. [1] http://article.gmane.org/gmane.linux.gentoo.user/269586 [2] http://article.gmane.org/gmane.linux.gentoo.user/269628 -- Canek Peláez Valdés Posgrado en Ciencia e Ingeniería de la Computación Universidad Nacional Autónoma de México
Re: [gentoo-user] RAID 1 on /boot
On Sat, Feb 22, 2014 at 12:41 AM, Canek Peláez Valdés can...@gmail.com wrote: [ snip ] [1] http://article.gmane.org/gmane.linux.gentoo.user/269586 [2] http://article.gmane.org/gmane.linux.gentoo.user/269628 Also, check [3], since the solution on [2] was unnecessarily complex. Regards. [3] http://comments.gmane.org/gmane.linux.gentoo.user/269628 -- Canek Peláez Valdés Posgrado en Ciencia e Ingeniería de la Computación Universidad Nacional Autónoma de México
