Choosing new Raid Card Help - AVS Forum
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post #1 of 19 Old 08-17-2010, 07:27 AM - Thread Starter
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I currently have an Areca 1231ML with 12 Seagate 1.5 TB drives in Raid 6

I am about out of storage space and I am looking for a new Raid Card, I'd like something that is SAS so that I can use an SAS expander upto 48 drives.

My plan would be to have 3 x 16 Drive Raid 6 Arrays on one card eventually, this should let me start with 2TB and hopefully then add new arrays at 3TB or 4TB in the future (keeping the 1231ML as well).

I have looked at other Areca cards, but I'm not sure which ones will do what I want:

ARC-1880ix-12 (or 16)
http://www.areca.com.tw/products/1880.htm

ARC-1680ix-12 (or 16)
http://www.areca.com.tw/products/pci...1680series.htm

LSI SAS 9201-16i
http://www.lsi.com/storage_home/prod...16i/index.html

LSI SAS 9211-4i
http://www.lsi.com/storage_home/prod...-4i/index.html

Again I plan to do Raid 6, and I want to be able to stream 2 blu-ray's at once. Thanks.
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post #2 of 19 Old 08-17-2010, 09:27 AM
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I thought of this and then got extremely worried. 2 parity drives for 48 drives is just insane. Thats almost guaranteeing a catastrophic failure. It sounds great because then you only waste 2 drives but is that really enough for that many drives? Not unless I misunderstand how it works and it really uses 2 per 16?
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post #3 of 19 Old 08-17-2010, 10:03 AM
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No, he said 3 16 drive arrays so 2 parity drives for each array (6 total). Which still seems kinda low.
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post #4 of 19 Old 08-17-2010, 11:12 AM - Thread Starter
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Well I could do 3 x 16 drive arrays raid 6 with a hotspare so 2 parity + 1 hot spare per 16 or I could do 4 x 12 drive arrays raid 6 so 2 parity per array or 8 parity total.

Any thoughts on the cards though? I am going to looking to purchase one within a month and I dont know if I aim for a $500 LSi or a $1000 Areca, I like the interface of the areca and the performance is great, not sure I need all the performance it has to offer though.
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post #5 of 19 Old 08-17-2010, 01:19 PM
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Good luck running multiple RAID 5 arrays on an Areca. The performance drops significantly, to 10MB/s. They are fast with a single array but not very good with multiple. I had a 1680LP with an HP expander card and had to remove the second array to get my perf back. I ended up selling both cards and going back to a 1231ML. They software i spretty awesome though and the OOB management rocks.
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post #6 of 19 Old 08-17-2010, 01:46 PM - Thread Starter
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So you think multiple 1231ML's would be the way to go? I've thought about doing that, and doing a 12 x 2TB array on it which would probably get me around 19TB usable with Raid 6. But again I don't know how long that would last me.
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post #7 of 19 Old 08-17-2010, 03:23 PM
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Have you considered buying sata/sas dumb hba's..there just controller cards without raid capabilities. Then you could use zfs/raidz2 to create a pool/s. Raid2 is raid6 whereas raidz is like raid-5. I was going to look for a 2/4 port external sata/sas controller then buy a enclosure and connect it to a port, buy another enclosure when needed add it to another port etc.... Then you just use zfs's utilities to add the extra storage to the pool/s. If you don't want to use solaris you can perhaps use http://www.nexenta.org/ to control the madness.

If you just want hardware raid:

Anyways...I use the 3ware, perc5/6, p400 at work to do pretty much what your saying however if your splitting up drives for multiple arrays your creating more overhead and wasting space...my opinion. Unless you just need multiple arrays...creating one large array spanning all the drives minus one hot-spare and then creating logical volumes within the array might be a better option. No wasted space for each array to have it's own parity and less overhead for the controller if you decided to use hardware raid. I just setup a storage server where the nas had 12 drives, I created a raid-6 array from 11 of those drives and one hot-spare. Withing the one array I setup LV's for the customer..one lv for the os, one lv for storage pool1, one lv for storage pool2, another lv for snapshots etc..

Just a idea...
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post #8 of 19 Old 08-17-2010, 03:46 PM
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not raid2 ...sorry raidz2
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post #9 of 19 Old 08-17-2010, 05:39 PM
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A hot spare isnt going to help you any if multiple drives fail. AFAIK on mine I still have to tell it to manually rebuild. Maybe it does this automatically but it still takes days to rebuild so if another drive were to go out you are still SOL. Its not much better than just having a known working drive sitting on a shelf and in fact having a spare drive laying around might even be better than a hot spare.
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post #10 of 19 Old 08-18-2010, 10:30 AM
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Most higher end cards use the hot-spare marked for the arrray " or global hot-spare, in the case of multiple arrays", automatically without intervention. The rebuild process depends on interconnect protocol, drive speed and what load the system is under during a rebuild. Personally I like raid-6 and feel comfortable using it without a hot-spare because it has dual parity and the likelihood two drive failures "under normal conditions" is extremely rare. However, if your inclined to use a hot-spare then that means you would have to have 3 drives fail before data loss upon a fourth drive failing. Zfs also, as of july 09, has raidz3 "triple parity".
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post #11 of 19 Old 08-18-2010, 02:43 PM
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Well if 1 drive failed the hotspare would start rebuilding the array which could cause a 2nd drive failure or 3rd of course its all math and probability but...
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post #12 of 19 Old 08-19-2010, 07:17 AM - Thread Starter
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To stream 3bluray I'd be looking at 120mbps or about 15Mb/s read speeds, I dont see why I couldnt get this with one GOOD raid card and multiple arrays?
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post #13 of 19 Old 08-19-2010, 08:49 AM
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You can get that with a single hard drive.
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post #14 of 19 Old 08-19-2010, 08:50 AM
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Quote:
Originally Posted by ogormask View Post

Well if 1 drive failed the hotspare would start rebuilding the array which could cause a 2nd drive failure or 3rd of course its all math and probability but...

Rebuilding doesn't cause a drive to fail. A drive fails when it is defective.
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post #15 of 19 Old 08-19-2010, 12:24 PM
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Agreed, I have never seen drives fail due to rebuilding parity. You can have multiple arrays if you want but it's more overhead for the card and chews up more space. Anyways, I can't justify paying $$ for a high end card when I can do what I need though software. Honestly, I was never a big fan of software raid but it's come a long way and ZFS implements it the best...my opinion. This leaves more money for me to purchase external sata/sas hba's and DAE's. I have a few people running openfiler and iscsi on commodity hardware using software raid and they have been happy for some time now. If I had my heart set on a reasonably priced card, instead of other options, I personally would opt for a 12/+ port 3ware card. I see better IOPS performance on there cards and they are available easily over the Internet. If I just had $ to throw around I might consider a MD100 and just add other unit/s when needed as they are expandable.
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post #16 of 19 Old 08-19-2010, 01:29 PM
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Or when its worn out and rebuilding puts a lot of stress on all the drives.
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post #17 of 19 Old 08-20-2010, 11:17 AM
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True, but that a defective drive/s. That's why I usually go with dual parity and a hot-spare or two. Also you can use monitoring utilities to monitor the SMART messages and be proactive about replacing problematic or failing drives before a failure occurs...other then a outright failure. Depending on what application you use you could have it email you about potential issues. Nothing is perfect ... Anyways, from a enterprise standpoint ....if your data is that important then you need backups.

Have a good day guys.
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post #18 of 19 Old 08-20-2010, 11:22 AM
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anyways... does anyone have a recommendation for him? lol
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post #19 of 19 Old 08-20-2010, 03:54 PM
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To be specific ..these are pricey but nice.

Adaptec 2252400-R 12-Port
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