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I have a Ubuntu PC using Ubuntu 19.10. In 2011 I had a serious car accident and one of the by products of said accident is an extreme difficulty holding things in my memory. Long term things are fine, as are things that I read, but I tend to forget, for example what I did last week.

My background before the accident was in IT (I was an MCSE) and I already had a Linux box setup as a media server for home using Mythtv.

After the accident I could no longer work, so I amused myself by changing distributions from Fedora to Ubuntu, adding hard drives to my Ubuntu system and various O/S upgrades etc over the years.

This brings me to my problem, I now have a large number of hard drives attached to my Mythtv system, but when I compare the amount of storage space that I have, to that which I am using, it's less that 1/2.

I need some kind person to look at my list of available drives, formats and files and suggest a way to rationalise things for best performance with some redundancy (I have no redundancy at present and I would be broken hearted if I lost everything) I do have the spare capacity to create some sort of raid.

These are the Available drives: Disk /dev/sda: 4001GB Disk /dev/sdb: 4001GB Disk /dev/sdc: 4001GB Disk /dev/sdd: 6001GB Disk /dev/sde: 4001GB Disk /dev/sdf: 128GB (ssd) Disk /dev/sdg: 2000GB Disk /dev/sdh: 4001GB

Total drives including a 256GB Solid state (not currently switched on) 128gb+256gb+2000gb+4001gb+4001gb+4001gb+4001gb+4001gb+6001gb = 28390GB or 28.39 TB

Of this space I am using a Storage LVM which is 13889gb in size and a boot drive / swap.

The PC has 8gb ram installed.

  • Is there a metric for "performance?". Is mythTV slow? Or are you simply tring to recover free space on those drives? – user535733 Feb 23 at 10:37
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    So you have about 28TB of physical drives and about 13TB in an LVM. How much data do you have? Are you saying you can not access the other ~15GB? If so I suggest you google search “Manage LVM”. You can probably extend your LVM to access the remaining physical storage space. Be careful though, if you have no data backups your data is at risk. – PonJar Feb 23 at 10:56
  • Thanks for the replies. In answer to the first post by User 535722, Mythtv is a bit slower than normal, but definitely not unusable. I am really trying to utilise available space, in the most effective way possible. The system is too big for me to backup, so I was thinking that some redundancy might be in order. Ponjar, the large 13Tb LVM contains all of my data, as well as backups from other systems. It is always about 99 per cent full. I could just extend the LVM, but I'm worried th would still be no redundancy and as you say, it would be sad to lose this data because of a failure. – David Maher Feb 25 at 0:57
  • I am now going to try to move my boot Ubuntu install from an orphaned raid 1 drive, which also hosts part of the lvm, to a faster SSD (the 256gb drive that I have already) This will hopefully become the boot drive. – David Maher Feb 26 at 22:20
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So here's what I did:

Installed a new copy of ubuntu using LVM on the 256GB SSd, but made the partition only 50GB, which allowed me to mirror it using Raid 1 and LVM. I then mirrored it with the 128GB SSD.

I then moved things around on my 12TB LVM partition so that I had enough separate drives free to mirror that storage volume as well.

I think it was important to make sure that the mirrored drives were all separate drives to the storage LVM and didn't contain any part of the main LVM partition, since I wanted redundancy, and if part of the mirror and part of the man 12TB partition were on the same physical drive, you could still potentially lose everything with a single drive failure. (It's possible, but I'm not sure, that LVM mirroring won't let you do that anyway).

So that's what I've done, the mirror is still synchronising, and will probably take a couple of days. All that's left to do is make sure that I can boot from both 1/2s of the SSD mirror.

  • Synchronization of the mirror is now complete, so there are 2 copies of the data. Now that this is done, I'm starting to think that it is quite inefficient space wise, to use a mirror for a large amount of data. I'll ask another question about changing to a raid array. – David Maher Mar 5 at 5:38

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