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Re: gpt and grub
by Peter 11 Apr '13

11 Apr '13

Quoting "Greg Bromage" <greg(a)bromage.org> > Craig Sanders wrote: >> one error in 10^14 bits is nothing to worry about with 500GB drives. >> it's starting to get worrisome with 1 and 2TB drives. It's a guaranteed >> error with 10+TB arrays....and even a single 3 or 4TB drive has roughly >> a 30-50% chance of having at least one data error. > > *nod* that's the root of my concern. And the "at least one" is the issue, > because once a disk fails, if there's a second error somewhere then it WILL > be encountered, because the rebuild has to traverse every sector of every > remaining disk. Out of curiosity, I googled for the 10^14 bits. http://www.zdnet.com/blog/storage/how-data-gets-lost/167 Cause of data loss Perception Reality Hardware or system problem 78% 56% Human error 11% 26% Software corruption or problem 7% 9% Computer viruses 2% 4% Disaster 1-2% 1-2% I find the 26% human error interesting. IMHO a lot of IT people underestimated quite often the impact of their work and the errors they make. Sometimes a simple solution may look worse on paper but it may save the day. Because it is easy to implement and harder to break;-) For the 10^14 Bits.. that was five years ago, and I am not sure whether still valid (a Terbyte was a lot in 2007). I have overnight synchronisation of ca. 3 TeraByte per night (deltas and some full-copies after maintenance), all from mirrored disks, and haven't seen any errors over the last 18 months. ZFS scrubs did not find errors as well. Regards Peter

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Re: gpt and grub
by Greg Bromage 11 Apr '13

11 Apr '13

Craig Sanders wrote: > one error in 10^14 bits is nothing to worry about with 500GB drives. > it's starting to get worrisome with 1 and 2TB drives. It's a guaranteed > error with 10+TB arrays....and even a single 3 or 4TB drive has roughly > a 30-50% chance of having at least one data error. *nod* that's the root of my concern. And the "at least one" is the issue, because once a disk fails, if there's a second error somewhere then it WILL be encountered, because the rebuild has to traverse every sector of every remaining disk. Of course, that might not be enough to cause the rebuild (and thus the array) to fail. And there's probably another set of probabilities to factor in there too. But I can guarantee you a probability of 1.0 (with no deviation) that it will happen on the array that holds the critical data you need to recover that your boss accidentally forgot to back up... :)

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Re: gpt and grub
by Petros 11 Apr '13

11 Apr '13

From: "James Harper" <james.harper(a)bendigoit.com.au> Sent: Thursday, 11 April, 2013 12:10:37 PM > Putting the error correction/detection in the filesystem bothers me. > Actually when I was checking over this email before hitting send it > occurred to me that maybe I'm wrong about this, knowing next to > nothing about ZFS as I do. Is a zpool virtual device like an LVM lv, > and I can use it for things other than running ZFS filesystems on? I have seen examples of (FreeBSD) UFS partitions on top of Zpools. http://www.markround.com/archives/37-ZFS-as-a-volume-manager.html I briefly considered it because of Samba 4 and ACL issues. ZFS (on FreeBSD, and Solaris, I think) supports NFSv4 ACLs, while UFS has POSIX ACLs (as Linux ext3/4 has). NFSv4 ACLs are close to Windows CIFS ACLs (much closer than Posix ACLs). Still, Samba is using Posix ACLs, and makes it harder for ZFS - on FreeBSD at least. The FreeBSD samba 4.0.4 port considers ZFS as underlying filesystem as untested and it needs some tweaks to get it working. The reason to use Posix ALs, I believe, is lacking Linux support for NFSv4 ACLs. There are RichACLs but they are not in the main kernel yet - OpenSuse has them in their kernel already. A question to ZFSonLinux - which ACLs are supported here? Regards Peter

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grub and bmc/ipmi
by James Harper 10 Apr '13

10 Apr '13

I am testing grub via a serial over ipmi on a HP ML110, and while it draws the grub screen correctly it is constantly redrawing it and eventually it gets more and more corrupt, and then more so once I hit a few keys. I've used GRUB via a HP ilo before and it seems fine, but this is a bmc which is a bit different. Any suggestions? Thanks James

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gpt and grub
by James Harper 10 Apr '13

10 Apr '13

I have a server that had 4 x 1.5TB disks installed in a RAID5 configuration (except /boot is a 'RAID1' across all 4 disks). One of the disks failed recently and so was replaced with a 3TB disk, and the goal is to replace the remaining 3 disks with 3TB disks to get more storage (holds Bacula backups so more storage = more online backup history). Being a 3TB disk I had to make it a GUID Partition Table, and aside from a clean install I did once where Debian installer just did everything for me, I've never used gpt before. I believe I'm supposed to make a partition called the BIOS boot partition... can I store data on here or is it separate to my existing /boot partition? I created such a partition and did grub-install /dev/sda but then on boot from that disk all I get is "GRUB _" (where _ is the flashing cursor). Any hints or links to good online resources would be appreciated. I've googled and can find a bunch of information about it but it's not working for me so I'm missing something somewhere... Thanks James

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bind9 pain with Debian squeeze.
by Andrew Spiers 10 Apr '13

10 Apr '13

Something seems to have gone wrong with my bind installation. There was an upgrade to this: Version: 1:9.7.3.dfsg-1~squeeze10 when the upgrade ran, the owner on /etc/bind/rndc.key got changed to bind:bind. The service can't start until I change it to root:bind, as discussed in Debian Bug 386791. However the package then sits at partially installed (because it couldn't start). Any time I try to install other software, this post-install script runs, changes the ownership on rndc.key again, and bind fails to start. I've tried tinkering with what I think is the postinstall script: /var/lib/dpkg/info/bind9.postinst but I can't much debug output. and it seems if I try to install the latest bind with dpkg, my edited version of that script gets overwritten. What is the right approach to solving this? Regards, Andrew.

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google calendar notifications
by John Wilson 07 Apr '13

07 Apr '13

I am trying to set up sms notifications for a shared gmail account. My wife and I both subscribe to a calendar on this account. I am trying to set it up so that we both get sms notifications about appointments but it doesn't seem to work for both of us. We have 3 gmail accounts, mine, hers and an additional account for "other" appointments. Any help would be appreciated. John Wilson

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Best way to copy a large directory tree
by Aryan Ameri 07 Apr '13

07 Apr '13

What's the best way to copy a large directory tree (around 3TB in total) with a combination of large and small files? The files currently reside on my NAS which is on my LAN (connected via gigabit ethernet) and are mounted on my system as a NFS share. I would like to copy all files/directories to an external hard disk connected via USB. I care about speed, but I also care about reliability, making sure that every file is copied, that all metadata is preserved and that errors are handled gracefully. I've done some research and currently, I am thinking of using tar or rsync, or a combination of the two. Something like: tar --ignore-failed-read -C $SRC -cpf - . | tar --ignore-failed-read -C $DEST -xpvf - to copy everything initially, and then rsync -ahSD --ignore-errors --force --delete --stats $SRC/ $DIR/ To check everything with rsync. What do you guys think about this? Am I missing something? Are there better tools for this? Or other useful options for tar and rsync that I am missing? Cheers -- Aryan

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Re: Transferring music to MTP devices
by Toby Corkindale 06 Apr '13

06 Apr '13

On 02/04/13 12:22, Brendon Oliver wrote: > On Tue, Apr 2, 2013 at 10:15 AM, Toby Corkindale > <toby.corkindale(a)strategicdata.com.au > <mailto:toby.corkindale@strategicdata.com.au>> wrote: > > Recent Android devices that run official firmware versions will only > support MTP for file transfers. > > > Can the community suggest an alternative music manager that supports MTP > devices that works cleanly? > > > I gave up wrestling with MTP to copy files to my Galaxy S3. Ended up > installing SSHdroid on it and now just scp stuff over by hand. I found > it seems to copy a a bit faster too than, eg, if I boot into windows to > drag & drop files within explorer (but that's probably subjective). Thanks for the suggestion. I could also use mtpfs, or adb push. However I'm specifically after an easy-to-use solution appropriate for someone who uses desktop environments. Cheers, Toby

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Wordpress anti-spam
by Russell Coker 03 Apr '13

03 Apr '13

Currently I'm using block spam by math (forcing commenters to solve a simple addition) and Akismet to stop Wordpress spam. This works reasonably well, now I get about a dozen comments in my spam folder a day (much less than it used to be). Does anyone have any other anti-spam systems that they can recommend? One thing I'd like is a plugin which only permits one pending or spam folder comment per IP address. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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