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• ubuntu server 12.04 new installation does not boot

  - by itsols

  I've just installed server 12.04 on a new machine. It's got two network cards and two hard drives. During installation it asked me if I wanted to make it RAID and I said ok to that. Finally, it came to the packages options and I chose things like Samba, LAMP, etc. And then it asked to reboot without the CD. Did that and that's where the problem started. Nothing comes on the screen. Only a blinking cursor. Has anyone experienced this problem? I'm guessing that it may be a RAID issue. Not sure. Any thoughts please...

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• Ubuntu 12.10 "fakeRAID" RAID0 installation

  - by João André

  I have 2 80 Gb HDD's with a RAID 0 motherboard configuration (Intel Z77, fakeRAID) with a 100 Gb partition running Windows 7 and a 60 Gb partition where I would like to install Ubuntu 12.10. However, even though the installer seems to correctly detect the RAID 0 array, GRUB2 is not installed and the computer boots into Windows normally. The same thing does not happen when installing Fedora 17. The installer (Anaconda) also detects the disk array, but GRUB2 installation is successful. What exactly are the differences between Ubiquity and Anaconda? And is there a way to correctly install GRUB2 in a fakeRAID system, since there are no alternative Ubuntu CDs?

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• How to Setup Software RAID for a Simple File Server on Ubuntu

  - by Sysadmin Geek

  Do you need a file server on the cheap that is easy to setup, “rock solid” reliable with Email Alerting? will show you how to use Ubuntu, software RAID and SaMBa to accomplish just that Latest Features How-To Geek ETC How To Boot 10 Different Live CDs From 1 USB Flash Drive The 20 Best How-To Geek Linux Articles of 2010 The 50 Best How-To Geek Windows Articles of 2010 The 20 Best How-To Geek Explainer Topics for 2010 How to Disable Caps Lock Key in Windows 7 or Vista How to Use the Avira Rescue CD to Clean Your Infected PC Install LibreOffice via PPA and Receive Auto-Updates in Ubuntu Creative Portraits Peek Inside the Guts of Modern Electronics Scenic Winter Lane Wallpaper to Create a Relaxing Mood Access Your Web Apps Directly Using the Context Menu in Chrome The Deep – Awesome Use of Metal Objects as Deep Sea Creatures [Video] Convert or View Documents Online Easily with Zoho, No Account Required

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• Removing mdadm array and converting to regular disks while preserving data

  - by Jeffrey Kevin Pry

  I have a 6 disk (2TB each) mdadm RAID 5 volume created in Ubuntu 12.04 Server. However, I'm moving to a different solution and want to "unraid" my disks but keep the data. Only 50% is in use. From what I can surmise I basically have to do this recursively for each physical disk. Fail the disk Format the failed disk Move a portion of files to the new disk. Reshape the array Shrink the logical volume md0 This seems like a very time consuming process. Is there an easier way to do this (automatically perhaps) without buying new disks to temporarily hold the data? I am also aware that during this processing my RAID volume will be degraded and vulnerable the entire time. I am not too concerned about this and will be using battery backup and moving the most important files off first. Thank you for your help!

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• Linux software RAID6: 3 drives offline - how to force online?

  - by Ole Tange

  This is similar to 3 drives fell out of Raid6 mdadm - rebuilding? except that it is not due to a failing cable. Instead the 3rd drive fell offline during rebuild of another drive. The drive failed with: kernel: end_request: I/O error, dev sdc, sector 293732432 kernel: md/raid:md0: read error not correctable (sector 293734224 on sdc). After rebooting both these sectors and the sectors around them are fine. This leads me to believe the error is intermittent and thus the device simply took too long to error correct the sector and remap it. I expect that no data was written to the RAID after it failed. Therefore I hope that if I can kick the last failing device online that the RAID is fine and that the xfs_filesystem is OK, maybe with a few missing recent files. Taking a backup of the disks in the RAID takes 24 hours, so I would prefer that the solution works the first time. I have therefore set up a test scenario: export PRE=3 parallel dd if=/dev/zero of=/tmp/raid${PRE}{} bs=1k count=1000k ::: 1 2 3 4 5 parallel mknod /dev/loop${PRE}{} b 7 ${PRE}{} \; losetup /dev/loop${PRE}{} /tmp/raid${PRE}{} ::: 1 2 3 4 5 mdadm --create /dev/md$PRE -c 4096 --level=6 --raid-devices=5 /dev/loop${PRE}[12345] cat /proc/mdstat mkfs.xfs -f /dev/md$PRE mkdir -p /mnt/disk2 umount -l /mnt/disk2 mount /dev/md$PRE /mnt/disk2 seq 1000 | parallel -j1 mkdir -p /mnt/disk2/{}\;cp /bin/* /mnt/disk2/{}\;sleep 0.5 & mdadm --fail /dev/md$PRE /dev/loop${PRE}3 /dev/loop${PRE}4 cat /proc/mdstat # Assume reboot so no process is using the dir kill %1; sync & kill %1; sync & # Force fail one too many mdadm --fail /dev/md$PRE /dev/loop${PRE}1 parallel --tag -k mdadm -E ::: /dev/loop${PRE}? | grep Upda # loop 2,5 are newest. loop1 almost newest => force add loop1 Next step is to add loop1 back - and this is where I am stuck. After that do a xfs-consistency check. When that works, check that the solution also works on real devices (such a 4 USB sticks).

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 6

  - by MarkPearl

  Learning Outcomes Discuss the physical characteristics of magnetic disks Describe how data is organized and accessed on a magnetic disk Discuss the parameters that play a role in the performance of magnetic disks Describe different optical memory devices Magnetic Disk The way data is stored on and retried from magnetic disks Data is recorded on and later retrieved form the disk via a conducting coil named the head (in many systems there are two heads) The writ mechanism exploits the fact that electricity flowing through a coil produces a magnetic field. Electric pulses are sent to the write head, and the resulting magnetic patterns are recorded on the surface below with different patterns for positive and negative currents The physical characteristics of a magnetic disk   Summarize from book   The factors that play a role in the performance of a disk Seek time – the time it takes to position the head at the track Rotational delay / latency – the time it takes for the beginning of the sector to reach the head Access time – the sum of the seek time and rotational delay Transfer time – the time it takes to transfer data RAID The rate of improvement in secondary storage performance has been considerably less than the rate for processors and main memory. Thus secondary storage has become a bit of a bottleneck. RAID works on the concept that if one disk can be pushed so far, additional gains in performance are to be had by using multiple parallel components. Points to note about RAID… RAID is a set of physical disk drives viewed by the operating system as a single logical drive Data is distributed across the physical drives of an array in a scheme known as striping Redundant disk capacity is used to store parity information, which guarantees data recoverability in case of a disk failure (not supported by RAID 0 or RAID 1) Interesting to note that the increase in the number of drives, increases the probability of failure. To compensate for this decreased reliability RAID makes use of stored parity information that enables the recovery of data lost due to a disk failure.   The RAID scheme consists of 7 levels…   Category Level Description Disks Required Data Availability Large I/O Data Transfer Capacity Small I/O Request Rate Striping 0 Non Redundant N Lower than single disk Very high Very high for both read and write Mirroring 1 Mirrored 2N Higher than RAID 2 – 5 but lower than RAID 6 Higher than single disk Up to twice that of a signle disk for read Parallel Access 2 Redundant via Hamming Code N + m Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Parallel Access 3 Bit interleaved parity N + 1 Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Independent Access 4 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, significantly lower than single disk for write Similar to RAID 0 for read, significantly lower than single disk for write Independent Access 5 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, lower than single disk for write Similar to RAID 0 for read, generally  lower than single disk for write Independent Access 6 Block interleaved parity N + 2 Highest of all listed alternatives Similar to RAID 0 for read; lower than RAID 5 for write Similar to RAID 0 for read, significantly lower than RAID 5  for write   Read page 215 – 221 for detailed explanation on RAID levels Optical Memory There are a variety of optical-disk systems available. Read through the table on page 222 – 223 Some of the devices include… CD CD-ROM CD-R CD-RW DVD DVD-R DVD-RW Blue-Ray DVD Magnetic Tape Most modern systems use serial recording – data is lade out as a sequence of bits along each track. The typical recording used in serial is referred to as serpentine recording. In this technique when data is being recorded, the first set of bits is recorded along the whole length of the tape. When the end of the tape is reached the heads are repostioned to record a new track, and the tape is again recorded on its whole length, this time in the opposite direction. That process continued back and forth until the tape is full. To increase speed, the read-write head is capable of reading and writing a number of adjacent tracks simultaneously. Data is still recorded serially along individual tracks, but blocks in sequence are stored on adjacent tracks as suggested. A tape drive is a sequential access device. Magnetic tape was the first kind of secondary memory. It is still widely used as the lowest-cost, slowest speed member of the memory hierarchy.

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• disks not ready in array causes mdadm to force initramfs shell

  - by RaidPinata

  Okay, this is starting to get pretty frustrating. I've read most of the other answers on this site that have anything to do with this issue but I'm still not getting anywhere. I have a RAID 6 array with 10 devices and 1 spare. The OS is on a completely separate device. At boot only three of the 10 devices in the raid are available, the others become available later in the boot process. Currently, unless I go through initramfs I can't get the system to boot - it just hangs with a blank screen. When I do boot through recovery (initramfs), I get a message asking if I want to assemble the degraded array. If I say no and then exit initramfs the system boots fine and my array is mounted exactly where I intend it to. Here are the pertinent files as near as I can tell. Ask me if you want to see anything else. # mdadm.conf # # Please refer to mdadm.conf(5) for information about this file. # # by default (built-in), scan all partitions (/proc/partitions) and all # containers for MD superblocks. alternatively, specify devices to scan, using # wildcards if desired. #DEVICE partitions containers # auto-create devices with Debian standard permissions # CREATE owner=root group=disk mode=0660 auto=yes # automatically tag new arrays as belonging to the local system HOMEHOST <system> # instruct the monitoring daemon where to send mail alerts MAILADDR root # definitions of existing MD arrays # This file was auto-generated on Tue, 13 Nov 2012 13:50:41 -0700 # by mkconf $Id$ ARRAY /dev/md0 level=raid6 num-devices=10 metadata=1.2 spares=1 name=Craggenmore:data UUID=37eea980:24df7b7a:f11a1226:afaf53ae Here is fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> # / was on /dev/sdc2 during installation UUID=3fa1e73f-3d83-4afe-9415-6285d432c133 / ext4 errors=remount-ro 0 1 # swap was on /dev/sdc3 during installation UUID=c4988662-67f3-4069-a16e-db740e054727 none swap sw 0 0 # mount large raid device on /data /dev/md0 /data ext4 defaults,nofail,noatime,nobootwait 0 0 output of cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid6 sda[0] sdd[10](S) sdl[9] sdk[8] sdj[7] sdi[6] sdh[5] sdg[4] sdf[3] sde[2] sdb[1] 23441080320 blocks super 1.2 level 6, 512k chunk, algorithm 2 [10/10] [UUUUUUUUUU] unused devices: <none> Here is the output of mdadm --detail --scan --verbose ARRAY /dev/md0 level=raid6 num-devices=10 metadata=1.2 spares=1 name=Craggenmore:data UUID=37eea980:24df7b7a:f11a1226:afaf53ae devices=/dev/sda,/dev/sdb,/dev/sde,/dev/sdf,/dev/sdg,/dev/sdh,/dev/sdi,/dev/sdj,/dev/sdk,/dev/sdl,/dev/sdd Please let me know if there is anything else you think might be useful in troubleshooting this... I just can't seem to figure out how to change the boot process so that mdadm waits until the drives are ready to build the array. Everything works just fine if the drives are given enough time to come online. edit: changed title to properly reflect situation

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• How do I align my partition table properly?

  - by Jorge Castro

  I am in the process of building my first RAID5 array. I've used mdadm to create the following set up: root@bondigas:~# mdadm --detail /dev/md1 /dev/md1: Version : 00.90 Creation Time : Wed Oct 20 20:00:41 2010 Raid Level : raid5 Array Size : 5860543488 (5589.05 GiB 6001.20 GB) Used Dev Size : 1953514496 (1863.02 GiB 2000.40 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 1 Persistence : Superblock is persistent Update Time : Wed Oct 20 20:13:48 2010 State : clean, degraded, recovering Active Devices : 3 Working Devices : 4 Failed Devices : 0 Spare Devices : 1 Layout : left-symmetric Chunk Size : 64K Rebuild Status : 1% complete UUID : f6dc829e:aa29b476:edd1ef19:85032322 (local to host bondigas) Events : 0.12 Number Major Minor RaidDevice State 0 8 16 0 active sync /dev/sdb 1 8 32 1 active sync /dev/sdc 2 8 48 2 active sync /dev/sdd 4 8 64 3 spare rebuilding /dev/sde While that's going I decided to format the beast with the following command: root@bondigas:~# mkfs.ext4 /dev/md1p1 mke2fs 1.41.11 (14-Mar-2010) /dev/md1p1 alignment is offset by 63488 bytes. This may result in very poor performance, (re)-partitioning suggested. Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) Stride=16 blocks, Stripe width=48 blocks 97853440 inodes, 391394047 blocks 19569702 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=0 11945 block groups 32768 blocks per group, 32768 fragments per group 8192 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 102400000, 214990848 Writing inode tables: ^C 27/11945 root@bondigas:~# ^C I am unsure what to do about "/dev/md1p1 alignment is offset by 63488 bytes." and how to properly partition the disks to match so I can format it properly.

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• How can I create a 4TB partition on my software RAID5 device?

  - by Kris Harper

  I have set up a RAID5 device with three 2TB hard drives using mdadm. The device was successfully created, but I cannot seem to create a partition on the device. When I try to make an ext3 or ext4 partition via Disk Utility, I get the following error Error creating partition: helper exited with exit code 1: In part_add_partition: device_file=/dev/md0, start=0, size=4000526106624, type= Entering MS-DOS parser (offset=0, size=4000526106624) MSDOS_MAGIC found found partition type 0xee => protective MBR for GPT Exiting MS-DOS parser Entering EFI GPT parser GPT magic found partition_entry_lba=2 num_entries=128 size_of_entry=128 Leaving EFI GPT parser EFI GPT partition table detected containing partition table scheme = 3 got it got disk new partition guid '' is not valid type '' for GPT appear to be malformed I have seen this question, but that seems to suggest using gparted to do the partitioning. I'm fine with doing that, but my RAID device doesn't show up in the list of gparted devices. I suspect because this is a RAID and not a regular disk. I have already created a GPT partition table on the device. How can I add a partition to my device?

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• How do I align my partition table properly?

  - by Jorge Castro

  I am in the process of building my first RAID5 array. I've used mdadm to create the following set up: root@bondigas:~# mdadm --detail /dev/md1 /dev/md1: Version : 00.90 Creation Time : Wed Oct 20 20:00:41 2010 Raid Level : raid5 Array Size : 5860543488 (5589.05 GiB 6001.20 GB) Used Dev Size : 1953514496 (1863.02 GiB 2000.40 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 1 Persistence : Superblock is persistent Update Time : Wed Oct 20 20:13:48 2010 State : clean, degraded, recovering Active Devices : 3 Working Devices : 4 Failed Devices : 0 Spare Devices : 1 Layout : left-symmetric Chunk Size : 64K Rebuild Status : 1% complete UUID : f6dc829e:aa29b476:edd1ef19:85032322 (local to host bondigas) Events : 0.12 Number Major Minor RaidDevice State 0 8 16 0 active sync /dev/sdb 1 8 32 1 active sync /dev/sdc 2 8 48 2 active sync /dev/sdd 4 8 64 3 spare rebuilding /dev/sde While that's going I decided to format the beast with the following command: root@bondigas:~# mkfs.ext4 /dev/md1p1 mke2fs 1.41.11 (14-Mar-2010) /dev/md1p1 alignment is offset by 63488 bytes. This may result in very poor performance, (re)-partitioning suggested. Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) Stride=16 blocks, Stripe width=48 blocks 97853440 inodes, 391394047 blocks 19569702 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=0 11945 block groups 32768 blocks per group, 32768 fragments per group 8192 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 102400000, 214990848 Writing inode tables: ^C 27/11945 root@bondigas:~# ^C I am unsure what to do about "/dev/md1p1 alignment is offset by 63488 bytes." and how to properly partition the disks to match so I can format it properly.

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• mdadm starts resync on every boot

  - by Anteru

  Since a few days (and I'm positive it started shortly before I updated my server from 13.04-13.10) my mdadm is resyncing on every boot. In the syslog, I get the following output [ 0.809256] md: linear personality registered for level -1 [ 0.811412] md: multipath personality registered for level -4 [ 0.813153] md: raid0 personality registered for level 0 [ 0.815201] md: raid1 personality registered for level 1 [ 1.101517] md: raid6 personality registered for level 6 [ 1.101520] md: raid5 personality registered for level 5 [ 1.101522] md: raid4 personality registered for level 4 [ 1.106825] md: raid10 personality registered for level 10 [ 1.935882] md: bind<sdc1> [ 1.943367] md: bind<sdb1> [ 1.945199] md/raid1:md0: not clean -- starting background reconstruction [ 1.945204] md/raid1:md0: active with 2 out of 2 mirrors [ 1.945225] md0: detected capacity change from 0 to 2000396680192 [ 1.945351] md: resync of RAID array md0 [ 1.945357] md: minimum _guaranteed_ speed: 1000 KB/sec/disk. [ 1.945359] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for resync. [ 1.945362] md: using 128k window, over a total of 1953512383k. [ 2.220468] md0: unknown partition table I'm not sure what's up with that detected capacity change, looking at some old logs, this does have appeared earlier as well without a resync right afterwards. In fact, I let it run yesterday until completion and rebooted, and then it wouldn't resync, but today it does resync again. For instance, yesterday I got: [ 1.872123] md: bind<sdc1> [ 1.950946] md: bind<sdb1> [ 1.952782] md/raid1:md0: active with 2 out of 2 mirrors [ 1.952807] md0: detected capacity change from 0 to 2000396680192 [ 1.954598] md0: unknown partition table So it seems to be a problem that the RAID array does not get marked as clean after every shutdown? How can I troubleshoot this? The disks themselves are both fine, SMART tells me no errors, everything ok.

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• Setting up Cluster Configuration using an existing web server as a Primary Node?

  - by RapidWebs

  Thanks in advance for any help which is issued! I am having a slight issue, and need help with the decision making process when it comes to setting up my Cluster Configuration, consisting on a line of Ubuntu Servers (12.04). We currently have a Primary node, which resides in the US within a Datacenter, but we are going to be using this for all serious bandwidth and resource intensive websites, and through a configuration of Virtualmin + Webmin, will be setup as a sort of pseudo-cluster, using Virtualmins Cluster Modules. Anyways, on to the issue: We also have a business line setup locally, with three servers. here are their specs: Intel P4 2.4 ghz, 1GB Ram, 110 gb sata, Ubuntu 12.04* AMD 1.3 ghz, 512MB Ram, 20 GB IDE P3 Xeon 800mhz (dual physical processors), 1GB Ram, 3 * 25 GB Raid Configuration (one in use for host operating system). The first machine is currently IN USE and is serving virtual hosts off a sub-domain. My question is this: How can I integrate the Secondary node (which will be the Primary node per say, in this smaller configuration...) which is currently in use, into the cluster configuration w/ the other two servers for: Sharing Resources Redundancy (HA?) NFS /w the two Raid Disks without having the FORMAT the secondary node, and start fresh moving all my services in to a DRBD network drive or something similar, and than restoring all active virtualmin's Virtual hosts. the idea is that I want minimal downtime to people currently being served from server2.mywebsite.com, and from what I understand, all services need to be on a NFS so that they can be mounted on demand and accessed from the other machine taking over (i.e. Heartbeat + DRBD Config.) but my issue is that i already have all these services installed to their default directory structure: how can i most easily setup this NFS and HA system, move all my desires services to this new drive, and do it with minimal down time, and without breaking Virtualmin and everything else on my server? even just some pointers, a thread i could read, or a step by step check list or run down of commands i could issue to get started would be great! thanks!

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• Virtual Disk Degraded

  - by TheD

  There is a physical DC with a Raid 1 Mirror, 2 Physical Disks, 500GB each. Dell Server Administrator is installed on the DC, and is reporting both physical disks are fine, online, in a good state etc. On a PERC S300 Raid Controller: Physical Disk 0:0 Physical Disk 0:1 However at the same time it's reporting that a virtual disk is degraded, what exactly does this mean? The virtual disk indicates it's State is in a Raid 1 Layout. Device Name: Windows Disk 0 If my understanding is correct then the Virtual Disk, when you drill down into Dell OpenManage should have both physical disks as members, as it is a mirror? Is this correct? However, when I drill down into the Virtual Disk, it only displays Physical Disk 0:0 included in Virtual Disk 1. I'm very new to server side/raid management etc. just while our server techy is away! Thanks!

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• low-cost RAID NAS for home use?

  - by gravyface

  Have a noisy, power-hungry Pentium 4 based Ubuntu server that I want to replace with a nice, low-power mini-ITX/Intel Atom-based machine to do my network services (DHCP, DNS, IPSec, Web/mail, FTP, etc.) and am thinking of a (hopefully) equally-low powered NAS using NFS over GbE with at least 1 TB space and a RAID 5 (preferred) or RAID 0 (likely) configuration for redundancy with a couple of spare disks I can swap in as needed down the road. Would I be better off getting a full sized ATX mobo/case and configuring the RAID internally? I really want to keep power consumption down as much as possible as I leave my home server up 24/7.

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• low-cost RAID NAS for home use?

  - by gravyface

  Have a noisy, power-hungry Pentium 4 based Ubuntu server that I want to replace with a nice, low-power mini-ITX/Intel Atom-based machine to do my network services (DHCP, DNS, IPSec, Web/mail, FTP, etc.) and am thinking of a (hopefully) equally-low powered NAS using NFS over GbE with at least 1 TB space and a RAID 5 (preferred) or RAID 0 (likely) configuration for redundancy with a couple of spare disks I can swap in as needed down the road. Would I be better off getting a full sized ATX mobo/case and configuring the RAID internally? I really want to keep power consumption down as much as possible as I leave my home server up 24/7.

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• What benchmark tool to use to benchmark hardware for VM server?

  - by Mark0978

  We are setting up a new piece of hardware to virtualize several of our servers on. Choices are RAID 5, RAID 6, and RAID 0+1. We are wanting to benchmark all three before we go live with the machine, but I'm not sure how to test the speed. Since we will be using it to host VMs, what will the actual disk traffic look like? What can I use to see if RAID 6 is too slow? Short of setting up the system with all the VM's on it and running that way, then redoing on all the work, I'm not sure how to test it. It them becomes more of a subjective test than an objective one. I'm worried that RAID6 will have too much overhead, that RAID5 will be to fragile with 3TB drives and I've never worked with 0+1 at all. So in short I'd like to setup the base machine (which will be running Linux) and then test the underlying SW RAID for speed. What kind of tool exists to simulate this kind of load? Barring the lack of a specific tool, how about a generic FS testing tool that will simulate different loads?

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• Missing over 100GB of Space on sda1 RHEL

  - by WifiGhost

  I have a server setup with a RAID 5 using (3) 500GB drives, 1 as a spare so unused in the RAID. So in my mind i start out with 990GB with the RAID 5 in place. When looking at DF or the built in disk space utility i only see a total of about 882GB, how can i find where the 100+GB went? How can i get it back? I've checked the RAID 5 BIOS and i see all the space. I've tried looking manually and through terminal commands with no luck. Filesystem - 1K-blocks - Used Available - Use% - Mounted on /dev/mapper/vg_web-lv_root 838084192 48368700 747153060 7% / tmpfs 12104644 592 12104052 1% /dev/shm /dev/sda1 495844 121546 348698 26% /boot /dev/mapper/vg_web-lv_home 82569904 259136 78116468 1% /home Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_web-lv_root 800G 47G 713G 7% / tmpfs 12G 592K 12G 1% /dev/shm /dev/sda1 485M 119M 341M 26% /boot /dev/mapper/vg_web-lv_home 79G 254M 75G 1% /home

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• Drive configuration for 5 large databases

  - by Mr. Flibble

  I've got 5 databases, each 300GB, currently on a RAID 5 array consisting of 5 drives. All the databases are used heavily, at the same time, so drive speed is an issue. Would I see better performance if I got rid of the RAID 5 configuration and just put each database on a separate drive? The redundancy provided by RAID 5 is not necessary due to mirroring elsewhere. Will the server then be able to perform reads / writes to different databases drives in parallel? More so at least than when it's in RAID? This is all on Windows 2003 / SQL 2008.

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• Are mobo raid controllers based on Intel ICH10R southbridge still considered software Raid?

  - by Breadtruck

  So do you still need specific software/drivers (intel matrix?) installed to manage the raid controller, setup the array. If the raid chipset is on-board the motherboard and it uses the CPU, and say I am using a Core 2 Quad Q9550, would a hardware based card still out perform the motherboard chipset? This is for a home workstation and I could spend $300 on a areca ARC-1210 PCI-Express x8 SATA II but I want to be able to justify the money for the raid card. My motherboard is a GIGABYTE GA-EP45-UD3P UPDATE: I was going to RAID5 using 4 500 GB drives, and I was going to buy a controller card but this article got me thinking hmmm....Toms-Southbridge Battle

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• Very slow disk performance on Dell PowerEdge 2950 w/ PERC 6/i running RAID 10

  - by vocoder

  I recently set up a server running Ubuntu 10.04 LTS on a Dell PowerEdge 2950 server - it has 6 500 gb 7200RPM SATA drives setup in a RAID 10 config. I am seeing extremely poor disk performance - the RAID array reports all disks are normal and using MegaCLI, it looks like the BBU is fine. hdparm -tT /dev/sda reports: Timing cached reads: 90 MB in 2.05 seconds = 43.96 MB/sec Timing buffered disk reads: 24 MB in 3.11 seconds = 7.72 MB/sec So as you can see, it takes forever to something as simple as an apt-get upgrade and even logging into the server. How do I go about troubleshooting what is causing this? I upgraded the firmware on the PERC 6i RAID controller to the latest, but didn't see any improvements.

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• AHCI and Memtest86+

  - by satanicpuppy

  I've got a motherboard with SATA AHCI enabled, and I need to disable it to run Memtest86+ (because Window's built-in RAM diagnostic tool isn't worth a barrel of warm snot), and because the Memtest developers are too lazy to fix the bootloader problem. Fine, I know how to do that. The problem is, I, in a moment of insanity driven by the fact that I work with hardware RAID cards all the time, felt the need to enable the onboard RAID. In retrospect, this was stupid: the onboard raid is a joke, but I'm stuck with it. My question is, if I disable AHCI am I going to lose the RAID information? I haven't been able to find a definitive yes or no anywhere, and I'm not in the mood to find out the hard way.

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• RAID 10: SPAN 2 vs SPAN 4

  - by LaDante Riley

  I am currently configuring RAID 10 (first time doing RAID ever) for a server at work. In the Configuration Utility. I am given the option of either span 2 or span 4. Having never done this before, I was curious if someone could tell me the pros and cons of for each span? Thanks The server is a Poweredge r620 with a PERC H710 mini (Security Capable) RAID controller. I have 8 600GB hard drives. I am creating this server as a network storage drive. I have SQL server historian database whose 1TB storage filled up and after 5 years of logging data.

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• How to make a Linux software RAID1 detect disc corruption?

  - by Paul

  This is one of the nightmare days: A virtualized server running on a Linux SW-RAID1 runs a VM that exhibits random segfaults in seemingly random codechunks. While debugging I find that a file gives different md5sums on each and every run. Digging deeper I find this: The raw disc partitions that make up the RAID1 mirror contain 2 bit-differences and ca. 9 sectors are completely empty on one disc and filled with data on the other disc. Obviously Linux gives back a sector from a undeterministically chosen disc of the mirror set. So sometimes the same sector is returned OK, sometimes the corrupted is given back. The docs say: RAID cannot and is not supposed to guard against data corruption on the media. Therefore, it doesn't make any sense either, to purposely corrupt data (using dd for example) on a disk to see how the RAID system will handle that. It is most likely (unless you corrupt the RAID superblock) that the RAID layer will never find out about the corruption, but your filesystem on the RAID device will be corrupted. Thanks. That will help me sleep. :-/ Is there a way to have Linux at least detect this corruption by using sector checksumming or something like that? Would this be detected in a RAID5 setup? Is this the moment I wish I used ZFS or btrfs (once it becomes usable without uber-admin capabilities)?

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• Slow Write Speed on ESXi host

  - by Gregg Leventhal

  I have an ESXi 5.0 free host with an internal datastore of 7.2K 5 disk RAID 5 using a PERC 710 mini RAID controller in a Dell Poweredge R620 Server with 32GB Ram and a 12 Core Xeon. I seem to get slow write speeds in the guests so I checked out ESXTOP and I see 15MB/s write speed there on this host, which is comprable to the guests. What could be causing such horrible write speeds? Is RAID 5 really this slow to write??

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• HP DL185 - very slow disk read speed

  - by fistameeny

  Hi, I have a HP DL185 G6 Server (12 disk model) with the following spec: Quad Core Xeon 2.27GHz 6GB RAM HP P212 RAID controller with battery backup 2 x 128GB 15K SAS 3.5" (RAID-1 for the operating system) 4 x 750GB 7.5K SAS 3.5" (RAID-5 for the data, 2TB usable space) The operating system is Ubuntu Server 9.10. Both drives have been formatted as EXT4. We are finding that read speed of the RAID-5 array is poor. Disk test results below: sudo hdparm -tT /dev/cciss/c0d1p1 /dev/cciss/c0d1p1: Timing cached reads: 15284 MB in 2.00 seconds = 7650.18 MB/sec Timing buffered disk reads: 74 MB in 3.02 seconds = 24.53 MB/sec For info, the RAID-1 array performs as follows: sudo hdparm -tT /dev/cciss/c0d0p1 /dev/cciss/c0d0p1: Timing cached reads: 15652 MB in 2.00 seconds = 7834.26 MB/sec Timing buffered disk reads: 492 MB in 3.01 seconds = 163.46 MB/sec We thought this was because with no battery, read/write cache is disabled. We have bought and installed the battery backup and have used the HP bootable CD to change the cache settings to 50% read / 50% write and check cache is enabled on the drives and the controller. Is there something I'm missing?

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