A newbs Q's on dmraid, SW RAID and partitions [LONG]

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A newbs Q's on dmraid, SW RAID and partitions [LONG]

Post by lazarus »

LM 18.3/19 Cinnamon x64
AsRock G90FX mobo - AMD Phenom IIx6 cpu - 16GB RAM

This could, perhaps, go into one of the more mainstream forums but the questions are still pretty newb... I hope you'll forgive the length of post. :oops:

My home Win workstation ran a pair of SSDs (RAID 0) for boot and 3x 2TB HDDs (RAID 5) for data. It would report random failures on the data HDDs and started taking ridiculously long times to rebuild the array when a replacement HDD was installed. (Identical models & size to existing.) On testing, the "failed" HDDs were perfectly OK. In desperation I replaced all 3 HDDs with new ones, only to find the problem continued. Until, recently, the RAID failed utterly and completely.

No surprise there... I had, of course, BU'd the data at the first sign of trouble.

To test for mobo failure (I was using the mobos alleged on-board HW RAID) I removed the boot array and replaced them with a 1TB HDD and LM18.2, rebuilt the data array using dmraid on the old "failed" HDDs and haven't had a problem since. :? I've since migrated to LM18.3 and am now moving to LM 19; a fresh install, not an upgrade. So I won't carry over any mistakes made during this... learning experience.

Current Situation:
I'm still wary of the HDDs and the mobo's fake RAID. So I disabled the BIOS RAID and switched to mdadm instead of dmraid.

I'm hoping to add the 3 new HDDs I bought to replace the allegedly failing ones - the mobo will support 8x SATA - to give me 2xSSD in RAID 0 for system/boot and 6x2TB in RAID 10 for data. RAID 10, for quicker rebuild times than R5 should it turn out that the HDDs actually are a tad dodgy.

  • After rebuilding the array in mdadm, I've sinced noticed files in /home and elsewhere that are part of dmraid. eg. /home/dmraid.pdc and /home/dmraid.sil
    Are these leftover artifacts from when I was running the BIOS RAID? Safe to delete now? Or does dmraid still have some place even though I'm no longer using the fake RAID and these are needed files?
  • mdadm will support RAID 10? I believe so, but everything I've googled refers to R 0, 1 or 5. Odd.
  • Most newb question of all... how to best partition things? Is there any definitive guide to this, or is it really just personal preference/experience?

    FWIW, I'm thinking the boot array should have /boot, /swap (30-ish GB for 16GB physical RAM?) and root partitions. I may add a 20GB /var partition at the end to limit log sizes. The data array(s), with 6TB to play with, would be partitioned for /home, /usr and I'd probably create a /backup partition for Timeshift snapshots, partition images (clonezilla?) etc.
  • I'd also like to create a common shared partition that all users had full access to; for stored multimedia over the LAN. /media perhaps? Where would be the best location to mount this? /mnt/local/media?
  • Assuming that I went with the above partitions, let's say 1TB ea for /home, /usr and /backup and 3TB for /media, is it possible to simply (relatively) resize the partitions while retaining existing data should I realise I'd badly mis-estimated the required sizes?
Again, sorry for the long winded post. :oops: I could've made several shorter posts... but then I'd be repeating a lot of the above in each, ending up with a larger overall posting anyway.
- Andy

I may be weird but I'm saving up to become eccentric.
Hoser Rob
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Re: A newbs Q's on dmraid, SW RAID and partitions [LONG]

Post by Hoser Rob »

TL;DR. Have you tried searching "ubuntu dmraid" and "ubuntu sw raid"?
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