Author Topic: Some general questions  (Read 1979 times)

Offline activoice

  • Newbie
  • *
  • Posts: 4
  • Karma: +0/-0
    • View Profile
Some general questions
« on: November 05, 2012, 03:26:04 pm »
I've been reading as much as I can in the wiki, and forum and have a few questions.

I've recently built a new server, includes one 500gb system drive, and six 3tb drives.  Five of the 3tb drives are almost full, I left about 15gb of empty space on them.  I've got a Mediasonic 4 bay enclosure that I plan to put four 2tb WD20EARS drives inside that I will connect over USB 2 that I plan to use as PPU's.

Is there some recommended ratio of PPU's to DRU's? 

If I add another three 3tb drives bringing me up to 27tb is 8tb of PPU still sufficient? if not how much PPU space should i have for 27tb of data?

I've already got my shares setup, and I don't plan to do drive pooling... So I've got my shares called \\Server\Movies1, \\Server\Movies2, etc..  Is that fine can I still access them directly like that after setting up FlexRaid?

My C drive will not be a DRU, it's basically system files, and where I do my downloading, and temporary storage... any issues copying files from my C drive, to the D drive directly, or should I be copying from the C drive to the share as \\Server\Movies1?


Sorry lots of questions...




Offline DrBlaze

  • Sr. Member
  • ****
  • Posts: 281
  • Karma: +14/-0
    • View Profile
Re: Some general questions
« Reply #1 on: November 05, 2012, 05:21:00 pm »
If you do a search for "usb" you will find a lot of stories about extremely slow speeds with flexraid and usb2.  You may get better results with usb3, but there is not much feedback from users at this point.

Also, each PPU must be at least as large as the largest DRU.  So your PPU must be at least 3TB.  You could span 2x2TB and have 2x4TB PPU, but having spanned PPU's is seen by many as not ideal.  Also some who have spanned  either DRU or PPU have reported slow speeds.  You won't really know until you set it up.

If I were you, I would transfer the data from 1 or 2 of the 3TB drives to your 2TB drives.  That way you can have 2 or 3 PPU's (all 3TB), with the rest of your 3TB's as DRU, and your 4 2TB's as separate DRU.

You can try things over usb2 but I suspect that Create, Update, Verify, etc. will be painfully slow.

Offline activoice

  • Newbie
  • *
  • Posts: 4
  • Karma: +0/-0
    • View Profile
Re: Some general questions
« Reply #2 on: November 05, 2012, 06:44:22 pm »
Ok so because I am using 3tb drives as DRU's I would have no choice but to use 3tb drives as PPU's..  ok so that's a bit of an investment.  (I'll have to think on it)

The enclosure actually has ESATA, so I guess speed wise I can just install an ESATA card that has NCQ / Port Multiplier support and that gets around the performance hit with USB 2.


How about my other questions..



Offline b-earl

  • Hero Member
  • *****
  • Posts: 660
  • Karma: +13/-1
    • View Profile
Sv: Some general questions
« Reply #3 on: November 06, 2012, 04:02:20 am »
Hi activoice

If you do not use pooling then flexraid will not interfere with you mounting of the drives. It will only create the parity on the ppu drives.
If you only use the raid function then you copy directly from drive c to d. If you have a pool, then you are not allowed to copy directly to drives.
« Last Edit: November 06, 2012, 04:07:30 am by b-earl »
Server HW: Chenbro RM41416 case | Supermicro X11SCZ-F + LSI SAS 9305-16i | i3-8300 | 16 GB DDR4 ECC Ram
Server OS:   Windows Server 2016 (UEFI) on  250 GB Samsung 970 Evo M.2 ssd
tRAID 1.1.0 2017.02.11
Backupserver: Supermicro X10SLM-F UEFI + LSI SAS9211-8i IT FW
Server OS: Win 2016 + tRAID

Offline activoice

  • Newbie
  • *
  • Posts: 4
  • Karma: +0/-0
    • View Profile
Re: Some general questions
« Reply #4 on: November 06, 2012, 08:39:51 am »
Ok great so that answers most of my questions... I was thinking I can buy some 3tb drives when the price comes down a little bit more, and stick those in the 4 bay enclosure connected over ESATA.

The only unanswered question really is... is there a recommended ratio of PPU space to DRU capacity...   so I was going with all 3tb drives... would 12tb of PPU be good to protect 27tb of DRU?  too much, too little?


Offline b-earl

  • Hero Member
  • *****
  • Posts: 660
  • Karma: +13/-1
    • View Profile
Sv: Some general questions
« Reply #5 on: November 06, 2012, 10:19:42 am »
Hi,
I use 1 ppu for 10 tb.
Personally I think I would use 2 ppu's for 27 tb. I think. 3 and above is overkill since with flexraid only the drive is gone not the whole raid.
Server HW: Chenbro RM41416 case | Supermicro X11SCZ-F + LSI SAS 9305-16i | i3-8300 | 16 GB DDR4 ECC Ram
Server OS:   Windows Server 2016 (UEFI) on  250 GB Samsung 970 Evo M.2 ssd
tRAID 1.1.0 2017.02.11
Backupserver: Supermicro X10SLM-F UEFI + LSI SAS9211-8i IT FW
Server OS: Win 2016 + tRAID

Offline DrBlaze

  • Sr. Member
  • ****
  • Posts: 281
  • Karma: +14/-0
    • View Profile
Re: Some general questions
« Reply #6 on: November 06, 2012, 10:52:16 am »
The only unanswered question really is... is there a recommended ratio of PPU space to DRU capacity...   so I was going with all 3tb drives... would 12tb of PPU be good to protect 27tb of DRU?  too much, too little?

It's probably best not to think in terms of Amount of TB.  Instead think in terms of # of DRU per PPU.  We RT users are limited for now to 1 PPU only (til RT becomes more stable), so I have 10 DRU and 1 PPU. If I could I would have 2, then I could have 2 simultaneous failures and still have all my data.  From reading posts by snapshot users, I would probably guess that on average they seem to like having 1 PPU for every 5-6 DRU.  Obviously it all depends on how crucial that data is.

Offline activoice

  • Newbie
  • *
  • Posts: 4
  • Karma: +0/-0
    • View Profile
Re: Some general questions
« Reply #7 on: November 07, 2012, 11:16:47 am »
Ok so if I am using Snapshot raid then I can have multiple PPU's but I have to perform snapshot's regularly I guess.  But if I go with real time, then I can only have 1 PPU, but the system keeps the parity data updated in real time.

I guess I could get one of those 3tb Western Digital drives that work over USB 3, and that should be sufficient for the PPU for now.


And it's ok to pretty much fill my DRU drives right... (leaving about 15gb of empty space) the PPU drive is the one that contains all of the data necessary for recovery?

Offline b-earl

  • Hero Member
  • *****
  • Posts: 660
  • Karma: +13/-1
    • View Profile
Sv: Some general questions
« Reply #8 on: November 07, 2012, 01:28:06 pm »
Hi,
It is in some threads written that it is better to change theorize from 15 to about the size of the biggest file you will copy to the pool. For example if you want to copy a blu ray that it should be st least 50 gb
Server HW: Chenbro RM41416 case | Supermicro X11SCZ-F + LSI SAS 9305-16i | i3-8300 | 16 GB DDR4 ECC Ram
Server OS:   Windows Server 2016 (UEFI) on  250 GB Samsung 970 Evo M.2 ssd
tRAID 1.1.0 2017.02.11
Backupserver: Supermicro X10SLM-F UEFI + LSI SAS9211-8i IT FW
Server OS: Win 2016 + tRAID