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22
votes
7answers
5k views

How can I use DD to migrate data from an old drive to a new drive?

I am upgrading the internal SATA hard drive on my laptop from a 40G drive to a 160G drive. I have a Linux/Ubuntu desktop which has a SATA card. I would actually like to do the same thing for a couple ...
19
votes
4answers
14k views

Clear unused space with zeros (ext3,ext4)

How to clear unused space with zeros ? (ext3,ext4) I'm looking for something smarter than cat /dev/zero > /mnt/X/big_zero ; sync; rm /mnt/X/big_zero Like FSArchiver is looking for "used space" ...
18
votes
4answers
33k views

linux: How can I view all UUIDs for all available disks on my system?

My /etc/fstab contains this: # / was on /dev/sda1 during installation UUID=77d8da74-a690-481a-86d5-9beab5a8e842 / ext4 errors=remount-ro 0 1 There are several other disks on ...
13
votes
1answer
2k views

How do pdflush, kjournald, swapd, etc interoperate?

Recently saw a question that sparked this thought. Couldn't really find an answer here or via the Google machine. Basically, I'm interested in knowing how the kernel I/O architecture is layered. For ...
10
votes
1answer
6k views

Understand output of `udevadm info -a -n /dev/sdb`

I plug an external HDD into my laptop. I try to find out the information by $ udevadm info -a -n /dev/sdb Udevadm info starts with the device specified by the devpath and then walks up the chain of ...
9
votes
1answer
3k views

Defragmentation of LVM2 logical volumes

Question: Is there a tool supporting de-fragmentation of LVM2 logical volumes ? (Making their extents into consistent sequences) Preferably by defining desired order of extents (something like ...
8
votes
1answer
199 views

How to re-size partitions in a complete hard drive image?

I have taken a complete image of a hard drive using: dd if=/dev/sda of=/home/user/harddriveimg bs=4M It would seem to me, that I should be able to re-size the partitions within it after suitably ...
8
votes
1answer
4k views

How can I check the condition of an SD card?

How can I check the health condition of an SD card? When I want to check a hard drive, I can use SMART, how should I check an SD card? Is there a universal approach?
7
votes
3answers
4k views

What is the best practice for adding disks in LVM

According to the Linux manpages you can add raw disks as well as partitions to a volume group. In other documentation (RedHat, CentOS or openSUSE), all examples refer to adding partitions to the VG ...
7
votes
5answers
767 views

how do I wipe a server that I don't have physical access to?

I have a Godaddy dedicated server that I would like to cancel. Before I do that I'd like to do a clean format on the server to make sure that the next person who gets the server isn't able to undelete ...
6
votes
3answers
4k views

How to resize a VirtualBox HDD image

I initially created a dynamically expanding VirtualBox image, and have tried to increase its hard drive space: VBoxManage modifyhd "VirtualBox VMs/JHBuild/JHBuild.vdi" --resize 16384 After that, I ...
6
votes
2answers
1k views

How to properly unplug/plug removable LVM2 device?

How to properly unplug (remove) and later plug (insert) removable (hot-plug, usb etc) storage device with LVM2 on it ? I've found this note Remove (unplug, eject): lvchange -an ...
6
votes
1answer
1k views

Move qcow2 image to physical hard drive

I have a qcow2 image that I use to boot an installation of linux using QEMU; I would like to place the contents of that image directly onto a physical hard drive so that I can boot to that linux ...
5
votes
3answers
2k views

Resume interrupted copying process

How to resume securely and reliably process of copying file $A into backup location $B done with pv "$A" > "$B" or cat "$A" > "$B" ? (let's assume file $A is very big, e.g. LVM2 snapshot file) ...
5
votes
7answers
18k views

Finding all storage devices attached to a Linux machine

I have a need to find all of the writable storage devices attached to a given machine, whether or not they are mounted. The dopey way to do this would be to try every entry in /dev that corresponds ...
5
votes
3answers
244 views

RAID 1 in linux

I'd like to setup RAID 1 with two drives in linux. I don't have a hardware RAID controller and don't want to buy one, so what is the best software RAID option for linux? Note: If it makes a ...
5
votes
1answer
2k views

Why can I not see some files in my USB stick on Windows that I can see on Linux?

I'm having a little problem with my USB stick. There are files and folders on the USB stick I can see and manipulate on my Linux machine (Fedora 20) but some of those files and folders appear nowhere ...
5
votes
3answers
529 views

FreeBSD 10 with Root-on-ZFS using only a part of the disk

I'm having a bit of trouble here. I'll try and be as concise as possible in describing my objective: I'm setting up a storage server for my employer, using two Intel DC S3500 series 120GB solid state ...
5
votes
2answers
526 views

How do I refresh the magnetic state on a disks with backups?

I have a couple of large disks with backup/archive material on them. They're ext4. Regarding the ones of those that will be stored for a couple of years without reading the whole disc again I've been ...
5
votes
1answer
229 views

Can I make a USB port on my Linux computer look like a mass storage device?

I'm running Kubuntu 12.04 on my PC. I want to make one USB port on my computer appear as if it is a USB mass storage device to other devices. In other words, something connected to this USB port will ...
4
votes
5answers
134 views

How do you layout extra storage

When I was doing dual boot all my extra storage was simple in /win/d, /win//e, /win/f, ... and formated ntfs. Now the desktop only runs Windows in a VM, and I access all my partitions from samba ( ...
4
votes
1answer
141 views

Disc light comes on when pressing keys in Iceweasel Preferences? Is this malevolent?

On Linux,I'm using the Iceweasel web browser (it's effectively Firefox), and in Edit/Preferences/General/Startup, when I type a URL into the "Home Page" box, the hard disc light comes on for EVERY ...
4
votes
2answers
148 views

Can you identify transport via sysfs?

I'm writing a script, and I'm interested in being able to identify the transport class (fc - "fibre channel", scsi, iscsi, etc.) for a given block device. I can retrieve this information via ls -l ...
4
votes
3answers
845 views

slow media - disk cache tuning?

Is there any way to make the system more consistent when using LUKS? (or slow storage in general) as it is everything is snappy until the write buffer is full, then everything grinds to a halt as the ...
3
votes
3answers
2k views

ReFS but for Linux

Microsoft is going to bring a "Resilient FileSystem" with Windows 8, but only for servers. I'd like that on a Linux desktop, but my search reveals no contender. There are so many filesystems for ...
3
votes
1answer
144 views

rsync move files, leave directories?

I'm using rsync to copy data between my internal and external hard drives. It's done what I need, but I'm running out of room on my internal hard drive. So, is there any way to get rsync to function ...
3
votes
2answers
125 views

Does using full-disk encryption affect the probability of losing data in case of storage errors?

So.. if there is a bad block on the HDD, what can survive better? not using FDE (full disc encryption) using FDE - since the whole disk has "1 partition" - the encrypted one, isn't it more likely to ...
3
votes
1answer
354 views

What are potential consequences of going nuts with sparse file based vdevs for a LVM to ZFS migration?

I've been playing around with ZFS having finally accepted that it's mature enough I shouldn't get burned. Now to migrate the home NAS box which is currently an LVM JBOD set up that's quite full, but ...
3
votes
2answers
212 views

Can lvm2 volumes based on device names like sda, sdb etc be mounted if their names change?

Lets say I would like to make a large volume from external usb drives. I create the lvm volume on drives that have been given certain device names sdf sdg or whatever and at some point they are ...
3
votes
1answer
78 views

Is there a more modern or more popular version of evms2?

I've just re-discovered evms having forgotten about it years ago thinking it was overkill for my needs. To my disappointment it appears to be unmaintained and not very well supported anymore. It ...
3
votes
1answer
2k views

How to enable (format) a disk in SunOS then add it to a DiskGroup?

SERVER # vxdisk list DEVICE TYPE DISK GROUP STATUS c1t0d0s2 auto:none - - online invalid c1t1d0s2 auto:none - - ...
3
votes
3answers
418 views

How to migrate data from server to server with as little downtime as possible?

I have a server running dovecot using the maildir format with a fairly large userbase (10k users or so) with each user having around a GB quota. The actual mail directories are stored on a separate ...
3
votes
1answer
328 views

How does ZFS grow/scale?

I am wondering how would one design a ZFS system to build something that is massively scalable, along the lines of your favorite cloud storage, but with all the neat benefits the come with ZFS. A ...
3
votes
1answer
226 views

Protecting data against bit rot

I have realized that I need to protect all of my photographs against bit rot (file corruption occurring at random due to errors in hard drives or network transfer). I recently discovered par2 which ...
3
votes
3answers
111 views

Share unchanging data from a central repository on a network

I have a bunch of different binary files (total size of all files is circa ~500GB) stored in a hard drive that is mounted to machine001. I have 200 other machines that need to access this data for ...
3
votes
1answer
180 views

Something like VMware “Changed Block Tracking” (CBT) in linux

I'm wondering if is there any possibility to track changed blocks in linux with an ext3/ext4 filesystem (or a specific one supporting it). I mean a feture like the Changed Block Tracking (CBT) ...
3
votes
1answer
2k views

Is it possible to change the sector size of a partition for zfs raidz pool in linux?

I've been migrating a zfs raidz pool on linux to new discs via virtual devices which were sparse files. I've used partitions on the discs as the discs are different sizes of 1.9T each. The last disc ...
3
votes
1answer
2k views

Clear unused space with zeros (btrfs)

How to clear unused space with zeros ? (I am asking for tool for btrfs filesystem) I'm looking for something smarter than cat /dev/zero > /mnt/X/big_zero ; sync; rm /mnt/X/big_zero Like ...
2
votes
2answers
177 views

How to securely export a device (HDD)?

So I have a Scientific Linux 6.3 (RHEL clone so basically the question is Redhat related) machine called "B" (with an extra "A" HDD besides the system HDD) and a notebook with SL 6.3. They are in a ...
2
votes
3answers
86 views

Mount same disk to two linux machines - SAN/NAS

I do not know anything from storage and filesystems that's why i have created this question. I want to mount the same disk to two linux machines and both machine must be able to read/write on the ...
2
votes
1answer
443 views

Incremental file back up by date

Is there any backup tool that supports partial back up by date? What I mean is that I have some small drives such as on a laptop that can't hold a full copy of all the files on an external 2TB drive. ...
2
votes
1answer
4k views

What to do after the LUNS are created

Our Management bought a New EMC2 VNX storage device . And a guy from vendor came to create the LUNS. I honestly have no idea how to configure the EMC SANS as i never got a chance to work on such ...
2
votes
1answer
6k views

extending a partition by resize2fs

I have a 4 GB SD card. Before the image load root@ubuntu# fdisk -l Disk /dev/sdb: 3965 MB, 3965190144 bytes 49 heads, 48 sectors/track, 3292 cylinders, total 7744512 sectors Units = sectors of 1 * ...
2
votes
1answer
516 views

Trapping “READ FPDMA QUEUED”

Recently I encountered a kernel message: ata3.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x0 ata3.00: irq_stat 0x40000008 ata3.00: failed command: READ FPDMA QUEUED ata3.00: cmd ...
2
votes
1answer
192 views

What is the smallest LVM2 logical volume unit?

Could you ensure me that minimal LVM2 size Unit is one extent to which all sizes are rounded up ? Is 4MiB the default size of extent for LVM2 ? Can it be configurable or is it the only size ? Small ...
2
votes
1answer
1k views

How should I set up additional EBS storage on an Amazon EC2 instance?

One of my clients has three EC2 servers on the Amazon cloud, with several attached EBS devices: server 1 and server 2 are ubuntu micro instances, and server 3, the main production box, is a ubuntu ...
2
votes
1answer
114 views

Running comprehensive speed tests on a drive

I'm wondering if anybody knows of any free packages, scripts or command line tools that can report a comprehensive speed test on a drive (e.g. generating random data, and testing how long it takes to ...
2
votes
1answer
32 views

Ways to store data for command line API

I am developing an API in Unix environment for virtual machines. I have to store some information in a table about virtual machines. Currently I am using python dictionary of virtual machine objects ...
2
votes
2answers
99 views

What is a good way of layering zfs filsystems to manage unpredictable future workload that doesn't severely compromise performance?

I've been playing around with ZFS and using sparse files as virtual devices to learn how to use the zfs tools. It seems that there isn't much of a hit in performance by creating a raid pool out of ...
2
votes
1answer
3k views

Mount exFAT file system as user without hardcoding

I've "solved" the following problem, but not in a desirable way. First, mounting exFAT file systems in Linux was truly as simple as this site says. The catch is, "as long as you are root." A user ...