Re: OT: harddrive addition for RAID
On Mon, 17 Oct 2011 23:09:04 +0100 Raf Czlonka r...@linuxstuff.pl wrote: On Mon, Oct 17, 2011 at 06:12:00PM BST, Camaleón wrote: 1. does the HD need to be exactly the same as the one its being paired with ? Not necessarily, but you will lose the remainder difference space between the smallest and the bigger of the disks. If you were referring to the brand/model/serial number of the disks some people think is better they exactly match (me) others think the opposite. It's not just size that matters ;^) If you'd like your RAID array to perform better it's always better to have the disks identical - cache size, speed, etc. If you have drives which don't match, essentially your RAID will perform as good as your worst drive. Regards, Thanks Raf, I'll check the spec with care, and make sure they are the same before proceeding. Best wishes / 73 Richard Bown e-mail: rich...@g8jvm.com or richard.b...@blueyonder.co.uk nil carborundum a illegitemis ## Ham Call G8JVM . OS Debian Wheezy amd64 on a Dual core AMD Athlon 5200, 4 GB RAM Maidenhead QRA: IO82SP38, LAT. 52 39.720' N LONG. 2 28.171 W ( degs mins ) QRV HF + VHF Microwave 23 cms:140W,13 cms:100W,6 cms:10W 3 cms:5W ## -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20111018083511.4f92a...@debian.g8jvm.com
Re: OT: harddrive addition for RAID
On Mon, 17 Oct 2011 18:11:05 -0500 Stan Hoeppner s...@hardwarefreak.com wrote: On 10/17/2011 5:09 PM, Raf Czlonka wrote: On Mon, Oct 17, 2011 at 06:12:00PM BST, Camaleón wrote: 1. does the HD need to be exactly the same as the one its being paired with ? Not necessarily, but you will lose the remainder difference space between the smallest and the bigger of the disks. If you were referring to the brand/model/serial number of the disks some people think is better they exactly match (me) others think the opposite. It's not just size that matters ;^) If you'd like your RAID array to perform better it's always better to have the disks identical - cache size, speed, etc. If you have drives which don't match, essentially your RAID will perform as good as your worst drive. Also keep in mind that with software RAID you won't be mirroring drives but partitions, since you're looking to mirror your boot/system drive. Getting your BIOS, boot loader and mdraid setup correctly so that the surviving drive boots the system after the other fails can be very very tricky, especially for a Linux RAID novice. If this is what you want to accomplish, then you have a lot of reading and research ahead of you, and likely some trial and error, along with headaches. Given the costs, learning curve, and ease of use issues, if I were you, I'd simply purchase a good cheap real RAID0/1 card and two new matching 500GB drives. Something like this combo: 1 x http://www.newegg.com/Product/Product.aspx?Item=N82E16816116075 2 x http://www.newegg.com/Product/Product.aspx?Item=N82E16822136073 Setting up a RAID1 set will be pretty easy with this card, and if one drive fails the card simply boots the other automatically and writes the failure to a log file and/or sends you an email. No hoops you have to jump through as with mdraid. And you'll also get a nice little speed bump due to the 128MB of cache on board. If your system is connected to a good working UPS you can enable write caching for even better performance. Total cost of these parts from Newegg is about $270+shipping. All you need is a free PCIe x1 slot. If the cost isn't prohibitive, you'll be much happier with this solution. Thanks thats VERY informative, I'll check some prices and see whats in the piggy bank, it may involve bribing my wife with a pair of shoes ;) -- Best wishes / 73 Richard Bown e-mail: rich...@g8jvm.com or richard.b...@blueyonder.co.uk nil carborundum a illegitemis ## Ham Call G8JVM . OS Debian Wheezy amd64 on a Dual core AMD Athlon 5200, 4 GB RAM Maidenhead QRA: IO82SP38, LAT. 52 39.720' N LONG. 2 28.171 W ( degs mins ) QRV HF + VHF Microwave 23 cms:140W,13 cms:100W,6 cms:10W 3 cms:5W ## -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20111018083851.6ac97...@debian.g8jvm.com
Re: OT: harddrive addition for RAID [Warn: long message]
18/10/2011 01:11, Stan Hoeppner wrote: On 10/17/2011 5:09 PM, Raf Czlonka wrote: On Mon, Oct 17, 2011 at 06:12:00PM BST, Camaleón wrote: 1. does the HD need to be exactly the same as the one its being paired with ? Not necessarily, but you will lose the remainder difference space between the smallest and the bigger of the disks. If you were referring to the brand/model/serial number of the disks some people think is better they exactly match (me) others think the opposite. It's not just size that matters ;^) If you'd like your RAID array to perform better it's always better to have the disks identical - cache size, speed, etc. If you have drives which don't match, essentially your RAID will perform as good as your worst drive. Also keep in mind that with software RAID you won't be mirroring drives but partitions, since you're looking to mirror your boot/system drive. Getting your BIOS, boot loader and mdraid setup correctly so that the surviving drive boots the system after the other fails can be very very tricky, especially for a Linux RAID novice. If this is what you want to accomplish, then you have a lot of reading and research ahead of you, and likely some trial and error, along with headaches. Given the costs, learning curve, and ease of use issues, if I were you, I'd simply purchase a good cheap real RAID0/1 card and two new matching 500GB drives. Something like this combo: 1 x http://www.newegg.com/Product/Product.aspx?Item=N82E16816116075 2 x http://www.newegg.com/Product/Product.aspx?Item=N82E16822136073 Setting up a RAID1 set will be pretty easy with this card, and if one drive fails the card simply boots the other automatically and writes the failure to a log file and/or sends you an email. No hoops you have to jump through as with mdraid. And you'll also get a nice little speed bump due to the 128MB of cache on board. If your system is connected to a good working UPS you can enable write caching for even better performance. Total cost of these parts from Newegg is about $270+shipping. All you need is a free PCIe x1 slot. If the cost isn't prohibitive, you'll be much happier with this solution. While everything that's been said is true, such migration isn't that bad and you'll learn a lot in the process, and mdadm raid is a lot more flexible than hardware raid at the cost of a little overhead (only makes a difference if the system is very busy AND you can afford a real high hand card). You should buy two raid cards, just in case the first one fails in between two backups and isn't available anymore... Easiest way is to backup, wipe old drive, reinstall from scratch to a raid system and restore data as needed. Debian installer will let you do that just fine. You can even throw lvm and/or encryption in at the same time and get a fresh start ! If you really want it the hard way, I'll try to break it down for you from memory: _BACKUP _CHECK BACKUP CONSISTENCY _Put the new drive in, partition as needed without creating any file-system. _Install/check mdadm, initramfs-tools and busybox on your running system _Create a degraded raid setup mdadm --create /dev/md0 --auto=md --level=1 --raid-devices=2 missing /dev/sdb1 Here sdb1 would be your new drive partition, missing being the slot where your old drive partition will fit in the end. auto=md is a preference of mine, since the partition layout is set before the raid creation, I create a non partition-able raid (See man mdadm and the -a option in the create section). There are several options that can be interesting to set at creation time (chunks, name ...), they are not necessary and your raid will run just fine with the defaults. _Check that the raid is started (run it if necessary), and format it: cat /proc/mdstat mkfs.ext4 /dev/md0 Repeat the process for other partitions. From single user mode or from a live cd, copy over you existing data to the raid volumes (cp, rsync, whatever you like to use. Make sure to keep all permissions and file attributes.) _mount new system, bind mount /proc, /sys, /dev from the running system to the raid one. Mount /boot from the new system if it's an autonomous partition. _chroot on the raid system _populate /etc/mdadm/mdadm.conf with: su -c mdadm --misc --detail --brief /dev/md* 2 /dev/null | tee -a /etc/mdadm/mdadm.conf _Check mdadm hook scripts presence: find /etc/initramfs-tools/ -name mdadm If they aren't there, copy them over from /usr/share/initramfs-tools/. As an extra safety measure (this should not be necessary), you can do: echo -e raid1\nmd_mod /etc/initramfs-tools/modules It's not needed if you have MODULES=most in /etc/initramfs-tools/initramfs.conf. _Take note of filesystems UUID's: blkid /dev/md* Compare with the output of: ls -l /dev/disk/by-uuid | grep md _Adapt /etc/fstab, arrays will be assembled in initramfs, so you want only file-systems UUID's in there, no mdadm arrays or partitions ones. This is the
Re: OT: harddrive addition for RAID
On Mon, 17 Oct 2011 23:47:45 +0100, Richard wrote: On Mon, 17 Oct 2011 17:12:00 + (UTC) Camaleón noela...@gmail.com wrote: 2 questions:- 1. does the HD need to be exactly the same as the one its being paired with ? Not necessarily, but you will lose the remainder difference space between the smallest and the bigger of the disks. If you were referring to the brand/model/serial number of the disks some people think is better they exactly match (me) others think the opposite. 2. how easy is it to change from a non RAID config to a RAID config. ie. can I just put in the second HD and run something to automagically change the config to RAID ? I don't think so... manual reconfiguration is required which usually involves more than one command. Thanks Camaleon The reason I ask about matching the HDs is that I have a Hitachi 500 GB drive, I can add another 500 GB HD for GBP 32, but if it requires an exact match a Hitachi 500 GB HD will cost around GBP 50. There is no need to match the exact serial number, but the hard drive technical specifications (seek speed, cache size, interface...) to avoid having the array always degraded because of i.e., timeouts. But you can perfectly buy a Segate, WD or Hitachi hdd (now part of WD's business) that pairs with the specs of your current hard disk. As I said, other users prefer doing it by this way to avoid having both disks with a factory error (in the event there has been an error on the manufacturing process, both disks will be affected, so choosing different brands reduces this possibility). As for question 2 , I had a feeling that it would have to be a manual process :(, Comments appreciated Ugh, nope. Dealing with software raid is a very consuming and difficult task, remember that you are playing with data, the most valuable treasure you have :-) You have to care, for instance, about the bootloader and when something goes wrong, you need to make the proper steps to be able to boot the system with the raid in a degraded state. Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/pan.2011.10.18.11.42...@gmail.com
OT: harddrive addition for RAID
Hi, I'm thinking about adding another 500 GB HD to use RAID. 2 questions:- 1. does the HD need to be exactly the same as the one its being paired with ? 2. how easy is it to change from a non RAID config to a RAID config. ie. can I just put in the second HD and run something to automagically change the config to RAID ? -- Best wishes / 73 Richard Bown e-mail: rich...@g8jvm.com or richard.b...@blueyonder.co.uk nil carborundum a illegitemis ## Ham Call G8JVM . OS Debian Wheezy amd64 on a Dual core AMD Athlon 5200, 4 GB RAM Maidenhead QRA: IO82SP38, LAT. 52 39.720' N LONG. 2 28.171 W ( degs mins ) QRV HF + VHF Microwave 23 cms:140W,13 cms:100W,6 cms:10W 3 cms:5W ## -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20111017173934.19424...@debian.g8jvm.com
Re: OT: harddrive addition for RAID
On Mon, 17 Oct 2011 17:39:34 +0100, Richard wrote: I'm thinking about adding another 500 GB HD to use RAID. Hardware RAID or software RAID? If the latter, what kind of RAID, md or dm? And what kind of raid level: 0, 1, 1+0...? ;-P 2 questions:- 1. does the HD need to be exactly the same as the one its being paired with ? Not necessarily, but you will lose the remainder difference space between the smallest and the bigger of the disks. If you were referring to the brand/model/serial number of the disks some people think is better they exactly match (me) others think the opposite. 2. how easy is it to change from a non RAID config to a RAID config. ie. can I just put in the second HD and run something to automagically change the config to RAID ? I don't think so... manual reconfiguration is required which usually involves more than one command. Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/pan.2011.10.17.17.12...@gmail.com
Re: OT: harddrive addition for RAID
On Mon, Oct 17, 2011 at 06:12:00PM BST, Camaleón wrote: 1. does the HD need to be exactly the same as the one its being paired with ? Not necessarily, but you will lose the remainder difference space between the smallest and the bigger of the disks. If you were referring to the brand/model/serial number of the disks some people think is better they exactly match (me) others think the opposite. It's not just size that matters ;^) If you'd like your RAID array to perform better it's always better to have the disks identical - cache size, speed, etc. If you have drives which don't match, essentially your RAID will perform as good as your worst drive. Regards, -- Raf -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20111017220904.ga5...@linuxstuff.pl
Re: OT: harddrive addition for RAID
Hi, firstly: this is only offtopic if you're not running Debian. Richard (richard.b...@blueyonder.co.uk on 2011-10-17 17:39 +0100): Hi, I'm thinking about adding another 500 GB HD to use RAID. 2 questions:- 1. does the HD need to be exactly the same as the one its being paired with ? No. Assuming you're going with Linux software raid (md or lvm), you can do partition-level raid. So even if the disks are not of equal size, you can create partitions that are and use the remainder of one of the disks as extra (non-raid) storage. 2. how easy is it to change from a non RAID config to a RAID config. ie. can I just put in the second HD and run something to automagically change the config to RAID ? In general, it is not easy, and potentially very dangerous. But it's not rocket science either. Anyway, you should be prepared to do a lot of command-line typing where a single typo could possibly destroy your system. If you are already using LVM, that makes the process slightly less dangerous and significantly easier. This list can help you out. Just making sure you know what you're getting into :) Regards and good luck, Arno -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20111018003618.664f9...@neminis.loos.site
Re: OT: harddrive addition for RAID
On Mon, 17 Oct 2011 17:12:00 + (UTC) Camaleón noela...@gmail.com wrote: On Mon, 17 Oct 2011 17:39:34 +0100, Richard wrote: I'm thinking about adding another 500 GB HD to use RAID. Hardware RAID or software RAID? If the latter, what kind of RAID, md or dm? And what kind of raid level: 0, 1, 1+0...? ;-P 2 questions:- 1. does the HD need to be exactly the same as the one its being paired with ? Not necessarily, but you will lose the remainder difference space between the smallest and the bigger of the disks. If you were referring to the brand/model/serial number of the disks some people think is better they exactly match (me) others think the opposite. 2. how easy is it to change from a non RAID config to a RAID config. ie. can I just put in the second HD and run something to automagically change the config to RAID ? I don't think so... manual reconfiguration is required which usually involves more than one command. Greetings, Thanks Camaleon The reason I ask about matching the HDs is that I have a Hitachi 500 GB drive, I can add another 500 GB HD for GBP 32, but if it requires an exact match a Hitachi 500 GB HD will cost around GBP 50. As for question 2 , I had a feeling that it would have to be a manual process :(, Comments appreciated -- Best wishes / 73 Richard Bown e-mail: rich...@g8jvm.com or richard.b...@blueyonder.co.uk nil carborundum a illegitemis ## Ham Call G8JVM . OS Debian Wheezy amd64 on a Dual core AMD Athlon 5200, 4 GB RAM Maidenhead QRA: IO82SP38, LAT. 52 39.720' N LONG. 2 28.171 W ( degs mins ) QRV HF + VHF Microwave 23 cms:140W,13 cms:100W,6 cms:10W 3 cms:5W ## -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20111017234745.17bef...@debian.g8jvm.com
Re: OT: harddrive addition for RAID
On 10/17/2011 5:09 PM, Raf Czlonka wrote: On Mon, Oct 17, 2011 at 06:12:00PM BST, Camaleón wrote: 1. does the HD need to be exactly the same as the one its being paired with ? Not necessarily, but you will lose the remainder difference space between the smallest and the bigger of the disks. If you were referring to the brand/model/serial number of the disks some people think is better they exactly match (me) others think the opposite. It's not just size that matters ;^) If you'd like your RAID array to perform better it's always better to have the disks identical - cache size, speed, etc. If you have drives which don't match, essentially your RAID will perform as good as your worst drive. Also keep in mind that with software RAID you won't be mirroring drives but partitions, since you're looking to mirror your boot/system drive. Getting your BIOS, boot loader and mdraid setup correctly so that the surviving drive boots the system after the other fails can be very very tricky, especially for a Linux RAID novice. If this is what you want to accomplish, then you have a lot of reading and research ahead of you, and likely some trial and error, along with headaches. Given the costs, learning curve, and ease of use issues, if I were you, I'd simply purchase a good cheap real RAID0/1 card and two new matching 500GB drives. Something like this combo: 1 x http://www.newegg.com/Product/Product.aspx?Item=N82E16816116075 2 x http://www.newegg.com/Product/Product.aspx?Item=N82E16822136073 Setting up a RAID1 set will be pretty easy with this card, and if one drive fails the card simply boots the other automatically and writes the failure to a log file and/or sends you an email. No hoops you have to jump through as with mdraid. And you'll also get a nice little speed bump due to the 128MB of cache on board. If your system is connected to a good working UPS you can enable write caching for even better performance. Total cost of these parts from Newegg is about $270+shipping. All you need is a free PCIe x1 slot. If the cost isn't prohibitive, you'll be much happier with this solution. -- Stan -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/4e9cb609.2090...@hardwarefreak.com
