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Storage Raid Card...the excitement!

Discussion in 'Hardware' started by davie107, 26 Nov 2018.

  1. davie107

    davie107 Linux or Windows???

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    Hi All,

    I have set myself up a Plex server on an old desktop pc I had lying around. It is an AMD FM1 cheap and cheerful machine running ubuntu but does the job. The os is on a ssd and drives for storage.

    Currently I have 3x 2tb drives full with media, however it will need another drive soon and I could probably do with some redundancy incase of a drive failure.

    My mobo doesn't support raid, so I understand I can get a raid controller card to setup a raid array?

    Are there any cards people would recommend what should i be looking for, what would be the best Raid to set it up in, I was thinking 5 or 6 and adding extra drives?

    What would be the easiest way to transfer all of my data across and add drives at a later date?

    Thanks in advance
     
  2. Mister_Tad

    Mister_Tad Super Moderator Super Moderator

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    In before Gareth: RAID isn't backup. So don't rely on it as such.

    Back on track. RAID6 technically works with 4x drives, but it's kind of pointless (you may as well run RAID10), so you would be looking at RAID5.

    "It will need another drive soon" - due to capacity? In which case it will need two more drives soon if you want to use RAID5. Three more for RAID6, due to losing aforementioned capacity to parity.

    RAID6 is technically better for larger-ish SATA drives given the theoretical chance of an unrecoverable write error during a rebuild causing you to lose everything with RAID5. This is more of a mathematical exercise than an imminent risk though... I've been running RAID5 on 4x4TB for quite some time with no issues, though will be moving to double-parity and a larger array soon.

    With regards to RAID cards, all are not created equal - you'll be wanting a hardware controller with onboard cache (preferrably battery/flash-backed) for RAID5/6. There are cheap RAID adaptors that are have neither of these things and will A) suck performance wise and B) chew CPU cycles whilst they do it. Second hand cards on ebay with battery backed cache (usually abbreviated BBWC) will almost certainly come with a dead battery (if any at all), so factor this into the price.

    Cards with capacitor-backed flash (FBWC) are a better option for lower mainenance, as the capacitors tend to have a much longer service life before they start complaining.

    After a bunch of false stars with some ebay cheapos, I eventually picked up a new HP P222, using it for a while and been very happy with it. As it happens I'll be moving it on in the near future, but this is just because I'm moving to a larger dedicated NAS appliance.

    Transferring data is kind of a pain. The best option is to dump it all onto the fully-built array. This is difficult if you're re-using drives, unless you have some externals/backups that you can pull the data from.

    If you get a controller with online capacity expansion and online level migration, you could create a RAID5 3x2TB, dump what you can on there, and then grow it disk by disk. This is liable to take weeks, but may be the only option.

    As you're using linux, software RAID may be a viable option, though I've not used it in pretty much forever. @Gareth Halfacree may be able to offer more insight.

    I'm inclined to think that HW may be better in this case, as SW RAID is likely to be quite demanding of the CPU, and I'm thinking ECC memory may be a strong preference as well, which could incur quite a bit of cost if your platform doesn't already support it.
     
    Last edited: 26 Nov 2018
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  3. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    \o/
    Plus side of software RAID: there's no extra hardware to break.
    Downside of software RAID: there's no extra hardware to offload checksumming, provide a write cache, offer battery backup, and so forth.

    Personally, I use software RAID - but I'm only using it in its absolute most basic form, a simple mirror, and the server's on a UPS so there's less need for a battery backup on the drives themselves.
     
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  4. davie107

    davie107 Linux or Windows???

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    Thanks for the reply, the media is all ripped from dvds or downloaded so not massively worried about backup currently as nothing is irreplaceable (just time) but once I sort the server a backup will be created.

    Looks like Raid 5 it is and 2 more 2tb drives.

    I had seen the Adaptec ASR-6805T which seem to be running about £35/£40 on ebay some with or without batteries. However i will look at the p222.

    I also have a spare 120gb ssd would this be worth adding in as a cache and how easy is that to do and would there be any benefit?

    In theory I could create the Raid 5 array with 3 drives and then transfer the files from one drive, add the drive in to create a 4 drive array and so on?

    Thanks

    David
     
  5. Dr. Coin

    Dr. Coin Active Member

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    With current drive sizes recovering a lost drive from a redundant system, takes a very long time and is at risk of error and or failure during the recovery process. I'd recommend staying clear of RAID, for a media system. Also often not discussed but using RAID adds one more level of failure to the system, the RAID controller. If the controller fails, and the drives are good you can only recover the data with a compatible controller. To use RAID you will lose at least 1 drives capacity to parity, thus expanding to 4 drives will not increase your storage capacity.

    For media I'd simple use a software JBOD or logical volume, easy to create under Linux. You probably won't notice the performance difference of software vs hardware and your not locked into one manufactures controller scheme, i.e. if motherboard fails or upgrading you can easily move the drives to the new system especially as you have a separate system drive. If the media is absolutely precious to you and any loss of data is unacceptable, then simple create a back up, preferable in a second machine and you can use any one of the abundant options for creating and maintaining the backup. Additional benefits, you can use mismatch drives sizes and it is easy to add drives as you go (only limited by SATA ports on motherboard).

    My personal NAS/plex server uses software RAID (stores more than just media). The plex server I built for my mother-in-law uses a logical volume, and this past summer I just added another drive to triple the storage (originally had 2x 1 TB added a 4 TB drive = 6 TB). The 4 TB cost less than the original 2x 1 TBs. If I'd being using RAID I'd would have been locked into buying 1 TB (or only using 1 TB of the drive capacity) alternative option and more painful would have been to rebuild the array with new drives.
     
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  6. davie107

    davie107 Linux or Windows???

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    Thanks, would JBOD require me to format the drives will it let you include subsequent drives further down the line? part of the reason to look for a Raid card is that I only have 4 Sata connectors of which i have the os ssd and 3 storage drives however a new mobo bay be cheaper than a raid card and an extra drive for parity. The drive sizes is a big reason why JBOD may work better for me currently.
     
  7. Mister_Tad

    Mister_Tad Super Moderator Super Moderator

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    @Dr. Coin makes a good point - it's worth taking a step back and instead of asking "how to RAID", maybe "should I RAID" is more valid.

    If we're just talking Plex + media here, where I don't even think having one logical volume will bring any appreciable benefit... you could get a cheap-n-dumb SATA HBA to add drives, and just point plex to the new location. Plex does the aggregating anyway so I'm not sure what a JBOD would give you on top of that.
     
  8. Dr. Coin

    Dr. Coin Active Member

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    It means that I don't have manage which drive I add files to.

    Exactly.
     
  9. davie107

    davie107 Linux or Windows???

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    Thanks for everyones input looks like JBOD is the way to go, anything to look out for when it comes to a sata HBA?

    Also
    Worst case happens if one of the drives fails? would it be whole files that i need to replace and i take it i would have to work out what files were saved on the failed drive?
     
  10. Votick

    Votick My CPU's hot but my core runs cold.

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    For ease of use and expand ability you should look into some sort of NAS.
    Can then easily swap the drives out for bigger disks when needed, RAID and 9/10 they run no issues.
    Just point Plex and sit back.

    23TB Plex - Dell R410 with Synology is my setup.

    The bigger boys on the Plex forums run similar servers and then shelves of Netapps (If only I had the space).
     
  11. Mister_Tad

    Mister_Tad Super Moderator Super Moderator

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    Good grief. Like legit supported kit, or ebay cast-off specials?
    The former (well either, tbh) seems like batsh_ levels of overkill for media. Not that I don't appreciate batsh_ levels of overkill (and I do have a soft spot for NetApp storage for reasons I won't go into here :lol:)
     
  12. Votick

    Votick My CPU's hot but my core runs cold.

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    Nah there all ebay or free kit from there work.
    One guy had a Netapp with 5 disk shelves - was something crazy like 90TB and this was maybe 4/5 years ago.


    EDIT: Found the thread - https://forums.plex.tv/t/largest-pms-server/86687/5
     
  13. Mister_Tad

    Mister_Tad Super Moderator Super Moderator

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    Noice. I used to use a few Centera units that I de-WORM/CASed that were cast-offs, but even those 1U nodes were a bit impractical... especially not having a rack at the time.
    I do have a colleague that's running Mcdata FC switches at home, that are probably 15-20 years old. Seems practical.
     
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