Software RAID 1 Woes.
May 21, 2009
I have a box colocated in a datacenter, and it seems like one of my drives have failed, but I need to find out what drive I need to ask the datacenter to swap.
cat'ing /proc/mdstat provides a very vague answer, but I was hoping someone could give me a better picture.
The harddrives are plugged into port 0 and 1 of the supermicro motherboard.
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid1]
md0 : active raid1 sdb1[1] sda1[0]
200704 blocks [2/2] [UU]
md1 : active raid1 sdb2[1] sda2[2](F)
624928384 blocks [2/1] [_U]
unused devices: <none>
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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.
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Jun 24, 2009
I am trying to set up my first VPS account and it has gone reasonably well until I was actually going to point my domain to the IP I have received. I am absolutely confused as how to set up my own DNS and the instructions I have found have not made me significantly smarter..
I am on Debian using DirectAdmin control panel. Domains are registered through NameCheap. What I first tried doing was just using the two DNS adresses that were in the DirectAdmin administrator settings panel as it was installed but this didn't seem to work and when pinging these hosts I didn't get an answer at all. I reckon this is not the way to do it..
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Jul 11, 2008
I've set up SPF records, reverse DNS, etc. but it seems that my 'virgin' IP is still being rejected as it's never sent mail before. I've sent an email to to MS as suggested in another thread, which was replied to later on saying "forwarded to our anitspam team"... but I haven't heard back since.
Any ideas what I'm doing wrong? Gmail accepts my emails without any hassle. I'm assuming (read: hope) ISPs are accepting my emails too... I was wondering if anyone has any idea how to test if other providers are accepting my email?
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Jul 16, 2008
My company went with Liquidweb over 3 years ago on the strength of positive recommendations given in this forum. For the most part things have been good, but service and quality have visibly deteriorated in the last few months, and I feel that the community should know. Here are a few examples:
1) We ordered a new dedicated database server from Liquidweb. It started crashing randomly, requiring a full system reboot. The only software we were running on this server was Postgres, which doesn't typically halt linux systems. The first time it crashed we chalked it up to a fluke. The techs at Liquidweb said it was probably "due to serverload", even though this server wasn't heavily stressed at all.
A few weeks later it crashed again. I talked to a Liquidweb tech and he said there were some weird hard drive related messages on the terminal in the datacenter. He said he would have a systems restore "specialist" look into it. This was at 3AM in the morning. The next morning, the server was back up, but we wanted an explanation for the down time. Another Liquidweb tech put us in touch with a systems restore specialist, who said that "we don't know went wrong. the error seems so sporadic that we cannot debug it without an error message." I asked him what happened to the error messages that were on screen the previous night. He said that someone had reboot the system without taking note of the error messages! So basically, his attitude was to wait for it to crash again, rather than proactively try to solve the problem!
I grew frustrated with them and asked him to run an HD scan to check the integrity of the disk. He said that they didn't really have any tools to do that except for one, and seemed reluctant to run it. I told him to do it anyway. It turned up massive failures with the integrity of the hard disk (on this, our brand new server). The fact that I had to basically tell him how to do his job to get our server back running was not the kind of service we were paying for.
2. This morning. For no reason, one of our webservers was unable to contact any of the internal servers in our network, resulting in downtime. I called a specialist at Liquidweb. He didn't know what was going on. I asked him to check the network cables, because the servers were still accessible via their remote ips, just not on the internal ones. He went down to the server room and said that the network cable from our webserver to the switch was simply unplugged. I don't even know how that could have happened, given the fact that it had been working fine for months, and we hadn't had any changes of hardware. Don't these cables snap in with a clip? Can someone explain to me how that is possible short of someone tripping over the wire, then failing to put it back in?
3. Now. The Liquidweb network has been down for an hour. Completely down, inaccessible. This must affect hundreds of sites. The explanation, given on the support page (liquidweb.com/support), is:
"We are currently experiencing latency and packet loss affecting portions of our network. Our network engineers are currently working on the issue and we will update this page as more information is available."
It doesn't seem like a latency or packetloss issue. It's a connectivity issue. Their network is down. Their Dedicated SLA guarantees 100% uptime. I'm not a network expert, but this would seem to imply some redundancy or failover. Which should prevent this currently impossible situation from happening.
We have multiple servers with them, and are currently spending thousands of dollars each month. Given that Liquidweb is more expensive than many other alternatives, a material portion of our monthly fees go towards that unseen "premium" of quality service and quality technology that now seems to be rapidly falling.
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Oct 3, 2008
I've been using Servint VPS hosting for the past few years and have been very happy with them. But unfortunately I have been experiencing problems for the last couple of months. My forums are regularly going down for a few minutes at a time and I have been submitting tickets to Servint.
Servint replied suggesting that my sites aren't going down. Yet I tried the sites on different PC's at different locations and they have been down. I started a thread on one forum and got confirmation from quite a few members that they experienced downtime. Servint have now accepted that there has been downtime.
I asked Servint for suggested solutions and they didn't provide any
I specifically asked if I needed to upgrade the VPS package, they originally said an upgrade wasn't necessary but 4 days later said that I did need an upgrade.
I've upgraded twice in the last few weeks and as of today I am on a Super VPS @ $199 / mth - Servint have confirmed that they have upgraded me to this package
But my sites have been down for about the last hour or two
In my ticket today, Servint have said "the longest your sites were down was 5 minutes".
This is simply not true, and even if it was true, regular 5 minute downtime is not acceptable in my view.
I feel that no one at Servint is taking my issues seriously. They had repeatedly told me that there was no problem but now they admit that there is one and they don't seem willing or able to fix it - this has been going on for a couple of months.
I ask "what am I doing wrong", because I see such great reviews of Servint here on WHT and I don't understand why I'm not getting the same level of service.
I have very limited technical knowledge - should I be using another type of hosting that provides more in-depth tech support?
Is it possible that the problems I am experiencing are outside of Servint's control and that I am expecting too much from them?
I want to stay hosted with Servint, but I'm having great difficulties at present. Given the great reviews I see of Servint, I'm actually concerned that they will tell me that my business is not worth the trouble and that I should host my sites elsewhere. What should I do?
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May 1, 2008
I'm trying to upload about 200 Gb of data and it became clear to me to route it out a specific connection sftp was the way to go.. (the ssh2 kind)
The problems I'm now having is that the 2 applications I rely on cannot get the job done.. CuteFTP Pro 8 can't even begin to get it done it crashes, errors out etc. and for while there it looked like the free program WinSCP was going to get it done but now it errors out/crash's and while it actually did get about 1/4 of the data done, it seems to think when it reported it done.. it got it all (that is when it doesn't crash for no reason, these crashes only occurred mainly when I tried to get it do 3/4's or the rest of the data)
So anyway.. recommend me a good client app if you can.. (that does real folder sync transfers) preferably ssh2/sftp, I'm uploading to dreamhost if that makes a difference I assume it doesn't though..
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Apr 5, 2007
So we have 10 racks of mess in our custom colo cage. Each rack currently has 20+ servers, most with dual network interfaces hooked up, most racks with two switches and 3+ apc remote power strips per rack. Each rack is an APC 4 post unit [url]
We have no cable management trays and currently tie up cables with velco and zapstraps, trying to keep power cables to the left and cat5 cables to the right. Unfortunately, even with all our effort, it's really turning into a wall of cabling that is basically insulating each rack and causing a temperature issue (or the potential for one at least).
Even worse, we want to add in KVM over IP hooked up on nearly every server. While I see the great benefits of the KVM, I can't see how on earth we are going to make the cabling work out!
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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Jan 5, 2009
I am trying to determine if i really got RAID 5 from a server of ServerLoft.
But i am not really sure how, fdisk only show 1 HDD.
This is the screenshot of IRMC hopefully it help, what do you guys think?
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Apr 19, 2009
The answer to my previous seems to HARDWARE RAID because of the ability of the server to still function during a rebuild.
The hardware is 4 X 1TB Western Digital RE3 Drives
However which configuration would you suggest, RAID 5 or RAID 10?
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