Why not more than 19 disk and why not SAS Expanders?

I was just wondering why unRAID does not support more than 19 drives and also no support SAS expanders, at least standard LSI chip based expanders? Non-RAID expanders cards can be had on ebay for as low as $30-40 which is much better than those SATA port replicators, both in terms of reliability, price and performance!

can you provide a link to one?

I was just wondering why unRAID does not support more than 19 drives and also no support SAS expanders, at least standard LSI chip based expanders? Non-RAID expanders cards can be had on ebay for as low as $30-40 which is much better than those SATA port replicators, both in terms of reliability, price and performance!

Frankly more then 19 drives in one case is pushing it to begin with. Not to mention you have to have PSU that can support that many... or multiple PSU's.  For now, I think 19 drives is more than enough, and as drive sizes increase you can just remove older ones and replace them with the new higher capacities ones.

Lot of cases have 24 drives, there is a new Norco 4224 coming up in 2010, unRAID as I have seen it performs a staggered spinup of drives so that at least 24 drives should be possible with a quality 750w PS like the Corsair HX. Then, most cases/builds will end up with more than 20 SATA channels being available (2x 8ch SATA cards and at least 6x channels on the mainboard).

Using SAS expanders will allow daisy chaining chasis by just a single and cheap cable. Basically anything using the LSI X28 and X36 expander chips should work (example is the Chenbro CK13601 and the CK12803). The LSI 3080/3442 work well with expanders. I have got a 3442E-R off at ebay for $65. This is great value and will easily support daisy chaining up to four 24-bay chassis.

Here is a link to the 3442E-R:

http://www.lsi.com/storage_home/products_home/host_bus_adapters/sas_hbas/lsisas3442er/index.html

Starcat:

You may need to email [email protected] and request the SAS expander be added.  A post in the Feature Requests section may be a more appropriate place for it, but may go unseen by Tom.  Sometimes driver additions are very easy and can be included in the next beta, which in this case will be 5.0beta1.  This is an interesting concept I think several of us would be interested in.

Regarding the Norco 4224, I am very interested in this case as long as they use quieter fans.  This is the only thing that has kept me from going to a Norco case.  I may be able to tweak the software, but when it comes to hardware mods I lack anything that resembles competence.

Prostuff1:

Just because you don't have a need for a specific feature doesn't mean it shouldn't be included.  I started off thinking I would never exceed 6 drives in my system and 9 months later I am up to 12 and looking for a new case to hold them.  I for one love to see new features and support for additional hardware included in unRAID as it gives me so many options for the future.  If Tom can expand unRAID to support 30 drives, I'm sure someone would use it

On a side note, I would like to see double parity added before support for more drives is added.  Just my opinion though.

Prostuff1:

Just because you don't have a need for a specific feature doesn't mean it shouldn't be included.  I started off thinking I would never exceed 6 drives in my system and 9 months later I am up to 12 and looking for a new case to hold them.  I for one love to see new features and support for additional hardware included in unRAID as it gives me so many options for the future.  If Tom can expand unRAID to support 30 drives, I'm sure someone would use it

I agree with you, but I guess my concern stems from putting all of my eggs in one basket.

On a side note, I would like to see double parity added before support for more drives is added.  Just my opinion though.

I would prefer dual parity (similar to RAID6) and/or multiple arrays in one machine.  So I could split off one array for only my DVD backups and the another array for computer backups, and another for general file storage, etc.  Granted all of those would have to be protected by there own parity drive but it may be a "penalty" I am willing to take.

Do unRAID support more than one array in a single installation? I don't want to mess up with two separate computers, I just want to connect a second case by a SAS expander, I don't necessary need all drives to be in the same volume, however it would help with some clients, say a Popcorn Hour streaming client who can only access a SINGLE share for which the virtualization of unRAID user shares is a very cool feature!

What about using port multipliers?

http://www.addonics.com/products/host_controller/AD5HPMSXA.asp

WeeboTech, too expensive and too limiting for what they are. You basicaly can't connect to a second chassis with a reliable, lockable and single (infiniband) cable up to 24x disks. A side benefit in supporting some basic (LSI based) non-RAID SAS/SATA cards would be using 15k SAS drive for parity increasing (write) performance a LOT!

LSI have drivers for *all* operating system, they are cheap and they are OEM'ed by almost all major brand vendors like HP, IBM, Sun, .. so lot of cheap surplus on ebay. Multilane cables are inexpensive and a SAS expander is about $170 new, for 24x drives this is a a steal! Just add a chassis with a PS and support in unRAID and we'll get much bigger, reliable systems with better performance too. Sometimes swapping out drives for the next available size isn't feasable. It wouldn't be very compelling for someone using 1.5TB drives today to swap out 20 drives against 2T drives as the difference in size is just too small to justify the trouble and time involved in swapping out the drives. I would indeed like to be able to connect a second case, fill up for now and swap out drives *when* huger capacities like 3T get available at reasonable prices. This makes the upgrade window a little longer, so again, having only 18 drives max limit (not counting the cache drive and the parity drive) is a shortcut.

ftp222, there is a custom made 3x 120mm fanboard available for both the older 4020 and newer 4220 Norco cases. It cost $60 incl. shipping within cont. USA. You may also use 3x 140mm fans, they just feet side to side in the middle of the case and are an excellent seal.

Just added 24 drive support in unreleased 4.5.1 and working with a guy to get SAS controllers working.

Just added 24 drive support in unreleased 4.5.1 and working with a guy to get SAS controllers working.

Now, THIS is what I call GREAT News!

Please consider the LSI 3442 card as it is has good specs, works with all expanders and can be found everywhere cheaply.

Thanks for bringing this up, Starcat, and thanks Tom for great new features in the pipeline!

Just added 24 drive support in unreleased 4.5.1

<cough>

Any chance you'd bump the 5-disk restriction of the standard license by a disk or two?

Or maybe give the option to use that cache disk as a normal disk?

Personally, I think there should be a third paid level, somewhere between the Plus and Pro, like 8 or 12 drives for $99.  That would hit a sweet spot imo.

5 disks for 70 bucks...  He could give us a little break. (make them half the pro?) 

... (make them half the pro?)

Like a Semi-Pro license? 

Well back blaze has 67TB in one 4u chassis everything in for 7800$US. Check it out.

Yes they have two power supplies. They can fit 45 Hard drives standing straight up, and they run cool.

67 TB because they do raid 6. I think to go to that size, you would need multiple parity drives (2or3) to speed things up when checking for parity.

http://blog.backblaze.com/2009/09/01/petabytes-on-a-budget-how-to-build-cheap-cloud-storage/

No I would opt for redundant power supply and better faster controllers for that many drives, but they use this config in their day to day business (online backups).

All this said, I doubt I ever need more than 19-20 drives worth, although it would be great to buy a 24 drive case and be able to use all 24 drives. The only thing that bugs me, is not being able to see the serial number like you can in backblazes setup. BTW, their hard drives are held in place by gravity, standing straight up so you can see the serial numbers of the hard drives. Makwes for quick in and out replacement.

On that note, does unRaid support Hot plug SATA, or do you have to reboot everytime? I never tried it, I always shutdown the array, and reboot to change drives. Just curious.

On that note, does unRaid support Hot plug SATA, or do you have to reboot everytime? I never tried it, I always shutdown the array, and reboot to change drives. Just curious.

DO NOT hotplug a drive in unRAID!  There are multiple instances listed here that when that is done it can rearrange the drive naming (sdx, hdx) and cause all sorts of problems.  Some/most report that it cuases drive corruption and then a file system check/rebuild is needed.

On that note, does unRaid support Hot plug SATA, or do you have to reboot everytime? I never tried it, I always shutdown the array, and reboot to change drives. Just curious.

 

DO NOT hotplug a drive in unRAID!  There are multiple instances listed here that when that is done it can rearrange the drive naming (sdx, hdx) and cause all sorts of problems.  Some/most report that it cuases drive corruption and then a file system check/rebuild is needed.

I can attest to the drive naming changes with drives outside of the array.

I have not done this with a drive in the array, nor would I recommend it.

The array has to be stopped and started if there is a drive change within the array. In fact I think there are times when a reboot is required for the low lever md driver to detect the drive change.

Any news on the SAS cards and would the LSI SAS3442 be supported? Tom, others?

THANKS much again!!

sas in general? the mv8 is a sas card

Actually more like SAS cards supporting expanders like the LSI SAS3442 series with external SFF connectors.

These expanders, what affect do they have on the available bandwidth? Are they like port multipliers with low overhead?

No, not like Port Multipliers, very stable, mature and professional technology, much more like a switch.

http://www.avsforum.com/avs-vb/showpost.php?p=18005435&postcount=5288

http://hardforum.com/showthread.php?t=1484614&page=1

I have read a large majority of those 2 threads already but have yet to find anything which explains how they work or their affect on available bandwidth.

Also, I thought FIS-based Port Multipliers already acted much more like a switch.