Read Raid-disk On Non-raid System

May 22, 2008

I want to take some data from a raid-disk (taken from a raid-1 sstem). Put it into a new system already, but this system doesn't have any raid.

When viewing "fdisk -l", it said /dev/sdb doesn't contain valid partition. Is there anyway I can mount it now? I am on CentOS 4 box

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400GB Hard Disk Drives In RAID 0, RAID 5 And RAID 10 Arrays: Performance Analysis

Mar 7, 2007

Quote:

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.

[url]

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Onboard Raid 1 (Read Only After Testing)

Oct 27, 2009

I have a server with 2 hard drives.

1. I configured the onboard Raid 1, both as Volume0

I installed CentOS successfully. So I tested the RAID to see if the mirror really works

2. I took out hddA and boot hddB as single drive. it work!

3. Then I took out hddB and boot hddA as single drive. it work!

4. Then I plug back hddA & hddB back together & boot it up

It gives me many error screen, I had to login as repair screen with root password. It says everything is read-only. So I try to remount but it fails

#e2fsck -y /dev/sda1
#mount -t ext2 -o rw,remount /dev/sda1 /
#mount -n -o remount ext2 /dev/sda1 /
#mount -o remount,rw /

None above works. I wonder if I am not suppose to do that way the first place?

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Setting Up RAID System

Mar 31, 2007

I've never loaded Linux onto a RAID array before,

I have an Adaptec 2105S card, with 3 x SCSI HDD's attached, in a RAID5 setup. When I boot the Cent OS Server 4.4 CD, it says I don't have any hard drives attached. I am then prompted to select a device driver, but it does not show up in the list.

The options in the list are:
- Adaptec AACRAID (aacraid)
- Adaptec AHA-152x (aha152x)
- Adaptec AHA-2740, 28xx, 29xx, 39xx (aic7xxx)
- Adaptec Aic79xx SCSI Host Bus Adapter driver (aic79xx)
- Adaptec SAS/SATA Host Bus Adapter driver (adp94xx)

It says if I have a driver disk, hit F2. The problem is that I don't have a driver disk.

The manual tells me to visit [url]for drivers, but it's not offline. When I go to the download section for the card [url]the only *nix option, is SuSE.

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Raid 5 On System Volume

Jun 9, 2007

Ive just bought a Power Edge 2600 and I decided to setup the three disks that came with it as raid 5 (within PERC) and installed Win2003 Std. Works great.

But while browsing one of my MCSA books I read that using a raid 5 configuration on the system / boot volume it is next to useless as it offers no redundancy should a volume fail. (With respect to easily booting it back up should a volume fail)

I'm going to use Raid 1 (again with PERC) across two other drives for my exchange data but I'm worried about my system volume. Is my MS book talking about the OS not been able to rebuild data should a volume fail or is this a general rule for raid 5 setups?

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Why Is RAID 1, Just Use A Backup System/server

Mar 7, 2008

I haven't yet broken into the realms of dedicateds, although I have a decent VPS and am anticipating the need to get a dedi in the future.

Hence I'm wondering briefly why exactly RAID (insert some random number?) is recommended? I know it does something to do preventing hard drive failure, although would an efficient backup system be a decent alternative with regards to cost?

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Map Failed Software Raid Disk In Windows?

Jan 11, 2007

I took two harddrives out of a windows 2003 server and imported them as foreign disks in my pc

the problem is... when i imported them as foreign disks, windows xp decided to mark every partition on both disks as failed... even though it hasn't failed.

Problem is now, i cant map to a drive... i need to do this so i can do an NT backup from the data off the drive, then restore that data to a new drive.

Here is what disk management looks like:

http://www.digitallyhosted.com/disk_management.gif

However when i look at it in Active Partition Recovery.... without running any recovery tools... it sees the data on all the drives fine:

http://www.digitallyhosted.com/partition_recovery.gif

Is there anyway to get windows to stop being a complete pain about this and just map the drive.

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Hardware RAID: Is Motherboard RAID As Good As A Dedicated PCI-E Card

Mar 24, 2008

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?

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RAID Controller Randomly Dropped Off System

Mar 26, 2007

This problem has happened to me twice on the very same server. I can't seem to figure out what's wrong with it.

My raid controller is Areca 1160 + 1GB Ram + 16xWD4000YS. Initially I had the problem of the disk dropping from the array randomly. I suppose this problem has been fixed since I have upgraded disks firmware according to WDC suggestion.

But there's another problem now. From my observation, the controller is randomly dropped off the system. When this happen, I cannot read/write anything from the disk at all. I can SSH in and able to run Areca CLI tool to see what's going on but only to get the message saying that it cannot find any Areca controller.

My only option is to restart the server and fsck all those 16 disks (not fun). I checked the log on the RAID controller itself, there was no sign of problem at all. No alert, no disk being dropped off the array, no events logged at all.

I'm using CentOS 4.3. Firmware on the RAID controller is 1.41, latest is 1.42. (Stupid me for not upgrading firmware when server crashed.) I plan to take the server down for RAID firmware upgrade soon. I just hoped that it's just problem with the firmware, not the controller or backplane itself.

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Moving My Install From Single Disk To Raid 1 Disks

Oct 27, 2009

If you want a quick run down as to WHY I want to do this, read here

Basically, my ISP could not get my server running stable on a simple raid 1 (or raid 5) so what it came down to was having them install my system on a single disk. I don't exactly like this, main reason being, if the system (or HDD) crashes, I'll end up with another several hours of down time... So here is my proposal:

Please Note: This will have to be accomplished on a live System (full backups!) over ssh as I don't trust my ISP to do things right as described in my post above.

Current Setup:
CentOS 5.3 x86_64
Dual Xeon 5410
16GB RAM
4x 750GB HDDs

/boot - /dev/sda1 - 512MB (real 471MB) ext3
/ - /dev/sda2 - 50GB (real 46GB) ext3
/home - /dev/sda3 - remaining space (real 642GB) ext3

swap - /dev/sdb1 - 32GB
/backup - /dev/sdb2 - remaining space (real 659GB) ext3

/dev/md0 - /dev/sdc + /dev/sdd - raid 1 (NOTE: uses entire disk, no partitions!)

Proposed Solution:

Code:
vgcreate -s 64M vg0 /dev/md0

lvcreate -L 512M -n lvboot vg0
lvcreate -L 50G -n lvroot vg0
lvcreate -L 5G -n lvtmp vg0
lvcreate --extent 100%FREE -n lvhome vg0

mkfs -t ext3 -m 1 /dev/vg0/lvboot
mkfs -t ext3 -m 1 /dev/vg0/lvroot
mkfs -t ext3 -m 1 /dev/vg0/lvtmp
mkfs -t ext3 -m 1 /dev/vg0/lvhome
Now, I'd like to 'init 1' at this stage but I can't, so I won't (possible solutions?? Possible to umount the / partition??)

Assuming I'd have to do this on a fully live system, I'd disable all services that I can

Code:
/etc/init.d/sendmail stop
/etc/init.d/postfix stop
/etc/init.d/saslauthd stop
/etc/init.d/httpd stop
/etc/init.d/mysql stop
/etc/init.d/courier-authlib stop
/etc/init.d/courier-imap stop
/etc/init.d/amavisd stop
/etc/init.d/clamd stop
/etc/init.d/pure-ftpd stop
/etc/init.d/fail2ban stop
/etc/init.d/syslogd stop
Then we copy all of our data from the single partitions to the raid disks

Code:
mkdir /mnt/newroot
mkdir /mnt/newroot/boot
mkdir /mnt/newroot/tmp
mkdir /mnt/newroot/home

Code:
mount /dev/vg0/lvboot /mnt/newroot/boot
mount /dev/vg0/lvroot /mnt/newroot/root
mount /dev/vg0/lvtmp /mnt/newroot/tmp
mount /dev/vg0/lvhome /mnt/newroot/home
(I think I covered everything)

Code:
umount -l /dev/sda1 (/boot)
umount -l /dev/sda3 (/home)
cp -dpRx /* /mnt/newroot/
mount /dev/sda1 /boot
cp -dpRx /boot/* /mnt/newroot/boot/
mount /dev/sda3 /home
cp -dpRx /home/* /mnt/newroot/home/
Once we have everything copied, update /etc/fstab and /etc/mtab to reflect the changes we made:
vi /etc/fstab

Code:
LABEL=/home /home ext3 defaults 0 3
LABEL=/ / ext3 defaults,usrquota,grpquota 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
LABEL=SWAP-sdb1 swap swap defaults 0 0
To

Code:
/dev/vg0/lvhome /home ext3 defaults 0 3
/dev/vg0/lvroot / ext3 defaults,usrquota,grpquota 1 1
/dev/vg0/lvboot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
LABEL=SWAP-sdb1 swap swap defaults 0 0
Moving on, we make a fail safe in the event this doesn't work out:
vi /boot/grub/menu.lst

find

Code:
default=0
add after

Code:
fallback=1
Then we find (in the same file):

Code:
title CentOS (2.6.18-164.el5)
root (hd1,0)
kernel /vmlinuz-2.6.18-164.el5 ro root=/dev/vg0/vgroot
initrd /initrd-2.6.18-164.el5.img
Add before:

Code:
title CentOS (2.6.18-164.el5)
root (hd3,0)
kernel /vmlinuz-2.6.18-164.el5 ro root=/dev/sda2
initrd /initrd-2.6.18-164.el5.img
Where (hd3,0) is /dev/sdc. If the system fails to boot to the raid then it'll auto boot to the single disk (/dev/sda)

then update my ramdisk:
mv /boot/initrd-`uname -r`.img /boot/initrd-`uname -r`.img_bak
mkinitrd /boot/initrd-`uname -r`.img `uname -r`

And now to set up grub...

Code:
grub
> root (hd0,0)
> setup (hd0)
we should see something like this:
Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... yes
Checking if "/grub/stage2" exists... yes
Checking if "/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 (hd0)"... 15 sectors are embedded.
succeeded
Running "install /grub/stage1 (hd0) (hd0)1+15 p (hd0,0)/grub/stage2 /grub/grub.conf"... succeeded
Done.


Code:
> root (hd3,0)
> setup (hd3)
Again, we should see something like this:
Checking if "/boot/grub/stage1" exists... no
Checking if "/grub/stage1" exists... yes
Checking if "/grub/stage2" exists... yes
Checking if "/grub/e2fs_stage1_5" exists... yes
Running "embed /grub/e2fs_stage1_5 (hd1)"... 15 sectors are embedded.
succeeded
Running "install /grub/stage1 (hd1) (hd1)1+15 p (hd1,0)/grub/stage2 /grub/grub.conf"... succeeded
Done.

Code:
> quit
From here I think we're ready to reboot, can't see where I missed anything. If all goes well then I should see my volume groups listed in 'df- h'

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Disk Writes Extremely Slow On SATA RAID

Jan 10, 2008

I'm running into a problem with a relatively new (2 months old) server. I have just a few accounts on it, and I'm already noticing unusual loads, for the... load. After some benchmarking with bonnie++ (and plain old "dd") there is clearly a problem.

Version 1.03b ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
SERVER NAME 2G 9096 16 7725 2 2543 0 20609 32 621627 55 +++++ +++

Isn't a write-speed over 7MB/s reasonable to expect? Also look at the low CPU times...

Anyway running the same test on a similar but older AND busier server showed much better results than this. In fact dd'ing a 1GB file from /dev/zero "finished" in about 10 seconds but then pegged the server at 99% iowait (wa) for a full three minutes (until done being written from cache I assume), bringing load to 15.00

That's all the info I have so far... the data center just replaced the card (which gave no errors) with no effect. Running these benchmark tests is about the extend of my hardware experience.

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Any Experiences With Software-Raid 5 Vs Hardware-Raid 5? (e.g. Hetzner EQ9)

Sep 17, 2009

I could try the Software-RAID 5 of the EQ9 Server of Hetzner.

Does anyone here has experiences, how fast a hardware raid 5 compared against the software-Raid 5 is?

The i7-975 should have enough power to compute the redundnacy on the fly, so there would be a minimal impact on performance. But I have no idea.

I want to run the server under ubuntu 8.04 LTS x64.

On it a vitualisation like VMware the IO-Load could get really high.

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Whats The Best For Server With SATA Raid 1 And SCSI Raid 10

Jan 14, 2008

So I've just got a server with 2xSATA raid 1 (OS, cpanel and everything in here) and 4xSCSI raid 10 (clean).

Which one do you guys think will give the best performance:

1. Move mysql only to 4xSCSI raid 10
2. Move mysql and home folder to 4xSCSI raid 10

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How To Setup Software RAID-10 On Linux With /boot On RAID-1

Jul 8, 2007

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.

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Worth Having RAID 1 If Raid Arrays Break

Feb 25, 2009

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?

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Software Raid 1 - Rather Slow During Raid 1 Recovery

May 20, 2009

I have a new server and it is rather slow during raid 1 recovery after system installed

CPU: Intel Core2Duo E5200 Dual Core, 2.5Ghz, 2MB Cache, 800Mhz FSB
Memory: 4GB DDR RAM
Hard Disk 1: 500GB SATA-2 16MB Cache
Hard Disk 2: 500GB SATA-2 16MB Cache

root@server [~]# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sdb1[1] sda1[0]
256896 blocks [2/2] [UU]

md1 : active raid1 sdb2[1] sda2[0]
2096384 blocks [2/2] [UU]

md2 : active raid1 sdb4[2] sda4[0]
480608448 blocks [2/1] [U_]
[=======>.............] recovery = 36.7% (176477376/480608448) finish=1437.6min speed=3445K/sec

the sync speed is just 3.4Mb/second and the total hours needs to be more than 40 hours

Also the server load is very high (nobody uses it)

root@server [~]# top
top - 07:00:14 up 16:55, 1 user, load average: 1.88, 1.41, 1.34
Tasks: 120 total, 1 running, 119 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.0%us, 0.2%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.2%si, 0.0%st
Mem: 4148632k total, 747768k used, 3400864k free, 17508k buffers
Swap: 5421928k total, 0k used, 5421928k free, 569252k cached

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RAID 5 Vs RAID 10 In Shared Hosting Server

Oct 22, 2009

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?

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Turn Non Raid Into Raid On Live Server

Dec 23, 2008

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.

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3ware RAID Or Software RAID

Mar 24, 2009

MY server configure our drives with RAID-1.

How can I check it my server configure with 3ware or software raid ?

Also please advise me how can I monitor raid configuration that my raid is working fine or no ?

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RAID Or Not To RAID: Trying To Decide On A New Server

Jul 11, 2008

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?

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Raid 1 SCSI Or Raid 10 SATA 10k

May 23, 2007

Just curious what your thoughts are on performance:

2 SCSI Drives 10k w/RAID 1

or

4 SATA 10k w/RAID 10

Prices are not too different with 4 drives just being a tad more.

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Software Raid Vs. Hardware Raid

Jun 5, 2007

how well software raid can perform and how it compares to hardware raid. How does software raid actually work and is it worth it?

How should I look at be setting up software raid if I was going to? Would you recommend just to use hardware raid instead?

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RAID 10 Or RAID 5 With Online Backup

Dec 10, 2007

Which do you guys recommend of the following?

4x 73GB 15,000rpm SAS drives in a RAID 10

or

4x 73GB 15,000rpm SAS drives in a RAID 5 w/ online backup

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Raid Disk Partition Errorc :: Warning: Invalid Flag 0x0000 Of Partition Table

Mar 16, 2008

I have a disk in raid, but it seems raid is not working correctly. I took it out, and plug into another server without raid. However, fdisk shows error

Quote:

#fdisk /dev/sdb
device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.

The number of cylinders for this disk is set to 20023.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)

2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help):

Should I correct the partition table now, or should I put it in another raid for checking?

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4 15K SAS RAID 10 Vs. 8 7.2K SATAII RAID 10

Nov 3, 2009

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.

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2 X SSD Raid 1 Or 4 X SAS Raid 10 For Mysql

Apr 19, 2009

I'm currently using 4 x 15K SAS raid 10 for a mysql server for a pretty busy forum, it has no I/O problem.

Now i'm going to migrate to a new server that i'm building soon, I have choice of:

2 x Intel X25-E SSD RAID 1

or

4 x 15K Fujitsu SAS RAID 10

will be using Adaptec 2405 RAID card.

The OS will be installed on a seperate hard drive.

If I go with the SAS setup, will be about $200 cheaper.

Which one do you think is better for Mysql performance?

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Raid 5 Vs Raid 10 (4 Drives)

May 10, 2009

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?

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Would You Choose RAID 5 Or RAID 10

Mar 16, 2008

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.

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Build RAID 0 Or Raid 5

Aug 23, 2007

I'm trying to build a physical raid 0/5 that can plug in to any computer which has SCSI behind it.

What are components you recommend (case, cpu, motherboard, SATA ...)

This is first time raid builder so i don't really need an expensive components.

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RAID-1 Pair Plus One Vs. RAID-5 Set

Oct 22, 2007

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.

I think I just sold myself on RAID-5, didn't I.

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4 500 Gb Disks In Raid 10 Or 2 150 Gb Raptor Disks In Raid 1

Apr 27, 2008

I would like to hear which configuration you think will be better for a hosting server.

I have allready a raid controller in the server.

I am more concerned with security.

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