Not sure where to post this so i decided to post it here.
I have two drives for RAID 1. The bios RAID and centos recognize the RAID 1. I installed CentOS, and the machine works fine with RAID 1 after installation.
Let call that two drives are drive A and drive B. When I pull off drive B from the case, and insert the other drive which same size with drive B. Then i reboot the machine. The bios RAID recognize the new drive and i rebuild new drive from bios RAID, but when at boot it stuck and gives this message:
switchchroot: mount failed: no such file or directoru
Kernel panic- not syncing: attempted to kill init!
Later, i reinserted the drive B, and reboot then it goes back to normal.
I'm playing around with different configurations on my box at home and wanted to practice setting up RAID 1 - 2 harddrives. Here is how I set it up during install. It seems to be working fine, but are there any issues with this?
The Windows user in me wants to be able to verifty that there are indeed two identical copies here, but from my limited knowledge I don't know how to browse the contents of my second hardrive. Everything seems to work by being mounted on something else. How can I verifty that I have done this correctly? /etc/fstab verifies LOgVol01 and LogVol02 but not LogVol00 which is the swap. Is this normal for the swap space not too show up there? It also verifies /dev/md0 but not /dev/md1. Is this because it is a Logical Volume Group or does this indicate there is something wrong with my setup?
final question. I want to test this by unplugging my first hard drive to simulate a failure. what can i expect will happen here? does my bios have to be setup to try to boot from the second drive after the first, and then failing finding the first drive it will just boot from the second? But the RAID is configured to operate on two drives, so won't there now be a misconfiguration that might stop things from working? Maybe i'm missing something here.
I am currently using areca Raid card with Centos 5 which allows me to configure Raid 6 with SAS drives. But it is really costing a bomb not to say that the lead time in ordering the card is long. Performance wise is fantastic though. Anyone know of any cheaper alternative to areca that can support Centos 5 and Raid 6 SAS Drives?
Anyone know what is a suitable SATA Raid card that supports Centos 4.4/4.6? I tried 3ware 9550 it is suppose to support Centos 4.4, but gives a kernel panic instead.
Would this be a good setup for a VPS Serving system with 2x 500gb hard disks (up to) 8gb memory.... (Looking to use OpenVZ to create about 14-15 512mb VZ VPS's)?
Host machine to do nothing other than host the VPS's. Host O/S to be Centos 5 x64, guest O/S's to be the usual OpenVZ supported linuxes.
Make 2 software raid partitions 120mb, each | +- Make RAID 1, mounted at /boot
Make 2 s/w raid partitions Remainder of drive | +- Make 1 LVM Physical Drive, using RAID 1 | +- Make Logical Partition, 20gb, mounted '/' +- Make LP, Swap 16gb +- Make LP. ext3 remainder, mounted as '/vz'
Is it important what order I should make the Logical Partitions? Should I create a /tmp partition? If so, how much?
I have probably what is the most simple thing I'm going to have to do soon, but I have never done it so I'm looking for tips of how to do it because I dont want to screw it up.
I want to copy a CentOS install from one RAID array, to another. However, I have a drive image (27GB RAID array) of the old RAID array, but the new RAID array will be larger.
How can I copy the old CentOS install, to a new array?
Today we are going to conduct a detailed study of RAIDability of contemporary 400GB hard drives on a new level. We will take two "professional" drives from Seagate and Western Digital and four ordinary "desktop" drives for our investigation. The detailed performance analysis and some useful hints on building RAID arrays are in our new detailed article.
Is Motherboard RAID as good as a dedicated PCI-E card? I am guessing a dedicated card is the best option, though costs more.
We are looking at buying a barebones server from Supermicro. It features an onboard RAID controller which supports RAID 0, 1, 5 & 10 - but for some strange reason it will only support RAID 5 if you use Windows. Here is a link to the page detailing the RAID features.
[url]
We are going to be running Linux, CentOS 5.1, so we will only have the choice of RAID 0, 1 or 10. This isn't an issue, as having RAID 10 on 4x SAS (15k) drives will be fine for speed and stability. What is an issue is would this RAID controller be as fast or reliable compared to a dedicated PCI-E card? If it can only use RAID 5 in windows, does that suggest this controller is too reliant on software? It would be a nightmare to suffer downtime and data loss because the controller couldn't hack it during a drive failure, or one day it decided to bugger up the array when rebooting.
So that leads me to looking at this card, this looks very good for what we need. Are adaptec a reliable brand? I've seen it advertised for £200, which is a good price.
[url]
This card features RAID 5 and 6, would RAID 6 be better than RAID 10 for redundancy, or is it too slow to bother with? Also it seems to have a battery module available for it, what does this achieve? Cos surely if the power dies the hard drives and motherboard can't run off this little battery, or does it just help the controller stay alive long enough with some hard drive information in its memory if the power goes out during a rebuild?
I am in a somewhat complicated situation... I wanted to order a custom server with hardware 3Ware RAID controller but after over a month of waiting I was told the HW RAID controller, as well as any other 3Ware controller they tried, does not work with the motherboard used in the server from Fujitsu-Siemens and that they simply got a reply from FS that the controller is not certified to work with their motherboard.
So although I'd prefer a HW raid, I am forced to either choose a different webhost or setup a software RAID. The problem is, I haven't done that before and am somewhat moderately...scared
I have read a lot of the info about SW RAID on Linux that I could find through Google but there are some questions unanswered still. So I thought that perhaps some of the more knowledgeable WHT members could help me with this problem...
The server specs will be:
Core2Duo E6600 (2.4Ghz), 2GB RAM, 6-8x* 250GB SATA II HDDs, CentOS 4.4 or SuSe, DirectAdmin
* I prefer 8 HDDs (or actually 9) over 6 but I am not sure if their server chassis can hold that many HDDs, I am awaiting answer from them. They don't have any other drives beside the 250GB ones so I am limited to those.
The preferred SW RAID setup is to have everything in RAID 10, except for the /boot partition which has to be on RAID-1 or no RAID I believe, plus one drive as hot spare (that would be the 9th drive). I am quite sure they will not do the setup for me but will give me access to KVM over IP and a Linux image preinstalled on the first HDD so that I'll have a functional system that needs to be upgraded to RAID-10.
How do I do that? The big problem I see is that LILO or GRUB can't boot from a software RAID-5/10 so I will have to mount the /boot partition elsewhere. It's probably terribly simple...if you have done it before which I have not. I have read some articles on how to setup a RAID-5/10 with mdadm (e.g. [url] ) but they usually do not talk about how to setup the boot partition. Should it be setup as a small sized (100-200MB) RAID-1 partition spread over all of the drives in the otherwise RAID-10 array?
What about swap? Should I create a 4-8GB (I plan to upgrade the server RAM to 4GB in near future) RAID-1 swap partition on each of the disks or swap to a file on the main RAID-10 partitions. The second sounds simpler but what about performance? Is swapping to a file on RAID-10 array a bad idea, performance wise?
Is it possible to grow a RAID-10 array in a way similar to growing a RAID-5 array with mdadm (using two extra drives instead of one of course)? mdadm doesn't actually even mention RAID-10 despite it does support it without having to create RAID-0 on top of RAID-1 pairs if the support is in kernel, from what I know.
How often do RAID arrays break? Is it worth having RAID if a servers hard drive goes down? I was thinking it may just be a better option to just have a backup drive mounted to my system and in the even of a system failure just pop in a new hard drive, reload the OS, and then reload all my backups?
I am in the process of restructuring the infrastructure on our servers. I am thinking of using either RAID 5 (1 hot spare) vs RAID 10 as my 1U server has 4 HDD tray.
RAID 5 would have better capacity but RAID 10 has better overall performance. Which one do you guys go for a shared hosting server?
Is it possible to turn a non raided setup into Linux software raid, while it is live, and if it's the OS drive? Can you even software raid the OS drive remotely? I've been thinking about doing it for the redundancy (and possible slight performance boost for reads, but doing it more for redundancy). I'm using CentOS.
I've been talking to the Planet about trading in my four and a half year old "SuperCeleron" (from the old ServerMatrix days) Celeron 2.4 GHz system for something new. As part of their current promotions, I've configured a system that looks decent:
Xeon 3040, 1 gig of RAM, 2x250GB hard disks, RHEL 5, cPanel+Fantastico, and 10 ips for $162.
Not too bad. I could bump up the ram to 2 gb for, I think, $12 more, which I'm thinking about and wouldn't mind some thoughts on. But, the thing that has me really confused is RAID. I like the idea of doing a RAID 1 setup with those two hard disks. But, the Planet wants $40/month for a RAID controller to do it. I really don't want to go over $200 a month!
Any thoughts on alternative redundancy strategies that might avoid that cost? Software RAID does not seem to be offered by the Planet, unless I can figure out how to do it after installation (is that possible?) Better ideas in general on the server?
Are there any significant difference between 4 15K SAS HD in RAID 10 versus 8 7.2K SATAII HD in RAID 10? I have the same question for 2 15K SAS HD in RAID 1 versus 4 7.2K SATAII HD in RAID 10.
I have room for 4 more hard drives on my home server. My original goal was to go raid 10 but I've been thinking, raid 5 can support 4 drives and give more capacity. Which one would have better performance as software (md) raid? I'm thinking raid 10 might actually have bad performance as software raid, vs hardware, compared to raid 5. Would raid 5 with 4 drives be better for my case?
We are looking to build our first server, and collocate it. It will be a higher investment than just renting the server, but will be worth it in the long term, and we have already decided we are going to support the hosting business for a minimum of 3 years - so we might as well invest in a server from the outset to benefit from lower data center charges and higher redundancy and performance.
We are currently looking at Supermicro for servers as they offer 1U barebones systems with dual hotswappable psus and upto 4 hotswappable drives. This would be ideal for redundancy, and also for taking advantage of the speed and redundancy that a RAID 10 array would give you. These two factors combined are very appealing as it would reduce the possibilities of downtime and data loss. Obviously we will be backing up daily, but its good for piece of mind to know that you could potentially blow a PSU and 2 hard drives, and your server will still be up long enough for a data centre technician to replace the parts.
Now then, my business partner and I are currently deciding what the best all round hard drive configuration would be. He has decided that we should opt for SAS instead of SATA to have lower latency seek times, which would give us better performance. I agree, though this does increase costs considerably.
He is then arguing that we use RAID 5 on cost grounds. He says we should only use 3 of the slots to begin with, save money on one drive by not having a spare, and hope we don't have a drive failure - which sods law will happen. I'm not happy us cutting corners to save money, because if we gamble and lose, that's a hell of a mess we have ourselves in, and will cost us a load more time, reputation and data center charges to get ourselves out of it.
I say we might as well go for RAID 10 for that extra performance, and redundancy, you can potentially lose 2 drives so long as they aren't from the same mirrored pair. With RAID 5 you can only lose a drive, it takes longer to rebuild onto a spare, and during rebuild the performance takes a hit. Also RAID 10 is much faster than RAID 5, and at the expense of the cost of a drive.
Now the question we should be asking is... would a SATA2 RAID 10 array provide better performance than a SAS RAID 5 array?
So I think the choice we have to make is either go for RAID 5 and run with a hot spare, and stock a cold spare, or go with RAID 10 and stock 2 cold spares.
We are considering going with Seagate drives because they are high performance and have 5 year warranties. I have had to RMA two Western Digital drives already in the past 12 months, a raptor and a mybook, both deaths invoked data loss.
The server is going to be a linux web, email, dns and mysql box. It will likely feature a single dual/quad core processor, and 4-8GB of unbuffered ddr2 ram.
Question though on RAID choices... I'm considering getting 3 x 250GB SATA drives. Would it be better to make two of them a RAID-1 mirrored pair for my OS, home directories, and use the 3rd drive seperately for backups, swap, and perhaps some logs.... OR should I put all three drives into a RAID-5 set and treat it as a single logical drive?
my math says usable space would actually be identical... with 465GB usable in either setup. RAID-1 would be faster for I/O with no parity overhead... but one drive would not be redundant. On the other hand, RAID-5 would be fully redundant but have parity overhead for writes.
