June 26, 201214 yr My potential hardware includes an eSATA controller and two five disc enclosures. Can I buy unRAID plus and built two separate five disc arrays? That would give me ten discs but each array would only have five discs.
June 26, 201214 yr My potential hardware includes an eSATA controller and two five disc enclosures. Can I buy unRAID plus and built two separate five disc arrays? That would give me ten discs but each array would only have five discs. unRAID does not support multiple arrays. (in any version)
June 26, 201214 yr Author Thanks for the quick reply. I guess I have to think about the cost of the PRO version. That would allow me to have all ten drives in one array (even if they are in two eSATA enclosures), right? Thanks agin.
June 26, 201214 yr Do the enclosures have individual eSATA ports for all 5 disks in each enclosure? If it's just a single port on the enclosure and relies on port multiplication performance is going to be very poor.
June 26, 201214 yr Thanks for the quick reply. I guess I have to think about the cost of the PRO version. That would allow me to have all ten drives in one array (even if they are in two eSATA enclosures), right? Thanks agin. Correct, Assuming the hardware is supported. PS, the use of port multipliers is supported with certain chipsets, but you will see decreased speed on parity checks and rebuilds.
June 27, 201214 yr Author eSATA with PM will support up to 2 drives per port with acceptable speed. Oops, so my five drive enclosure only gets two drives? Too bad. One of fhe reasons I use the chassis is too keep the hot drives and the hot cpu in separate places.
June 27, 201214 yr eSATA with PM will support up to 2 drives per port with acceptable speed. Oops, so my five drive enclosure only gets two drives? Too bad. One of fhe reasons I use the chassis is too keep the hot drives and the hot cpu in separate places. No, with the right controller -- you can access all the drives through Port Multiplying. The point the poster was making, is that activities that simultaneously access 2 drives is probably OK. Activities that access > 2 drives at a time, will degrade performance. I had an 8-bay (2x4 drive port multiplying) config -- and that's definitely true. I'd get stutter on playback if I happened to hit 3 drives on the same PM supported card channel. Sometimes stutter even with 2 drives at the same time. Never with 1 drive.
June 27, 201214 yr Given that the unRAID CPU and graphics requirements are very light (probably in the 30-50W range) you will find about the significant source of heat are the drives. If you go with green drives then that is quite low too (perhaps 3W to 5W per drive). unRAID also spins down all the inactive drives (unlike a traditional RAID-1 or RAID-5 solution which requires all drives to be spinning). So even if you are streaming media to several different users you'll probably only have a few drives actually spun up at any time. The exceptions to this are when you are doing a parity check, rebuilding a failed drive or replacing a smaller drive with a larger one. In these cases all the drives have to be active as the full parity computation is being done. The current WD green drives use about 5.3W when running and 3.3W when idle, so even if you have a tower case with 12 drives in it and you are running them all you're only needing to cool about 60W, so a couple of fans and you're set. If you use 7200RPM drives then the power requirements rise to something like 12W per drive at full use, so then your cooling is going to be in the 150W range, still not a big issue. Just get a nice big case with a large diameter vent fan and a couple of intake fans in front of the drives. Regards, Stephen
June 27, 201214 yr Author No, with the right controller -- you can access all the drives through Port Multiplying. The point the poster was making, is that activities that simultaneously access 2 drives is probably OK. Activities that access > 2 drives at a time, will degrade performance. I had an 8-bay (2x4 drive port multiplying) config -- and that's definitely true. I'd get stutter on playback if I happened to hit 3 drives on the same PM supported card channel. Sometimes stutter even with 2 drives at the same time. Never with 1 drive. Got it. Wow, this is a great user community.
June 27, 201214 yr Author Given that the unRAID CPU ... ... so a couple of fans and you're set. Regards, Stephen The math seems to work but I've just seem to have seen serious heat issues when everything is stuffed into an old desktop case. Either that or the thing roars from all of the fans.
June 27, 201214 yr I had an 8-bay (2x4 drive port multiplying) config -- and that's definitely true. I'd get stutter on playback if I happened to hit 3 drives on the same PM supported card channel. Sometimes stutter even with 2 drives at the same time. Never with 1 drive. I'm planning on extending my current setup with an external closure. I have no experience on eSATA but to my understanding the current standard interface speed is 3.0Gbps, same as with SATA II. Since single playback could reach 70-80Mbps (high bitrate blu-ray) I do not understand how 3 streams from individual disks over single channel could cause any problems. A single disk can easily have a effective burst rate over 100MBps, that is 800Mbps which is nowhere near the theoretical bus speed of 3.0Gbps. So 3x70Mbps=210Mbps should be peanuts to any interface. Is my math totally of the mark or is there something funny going on with eSATA with port multiplier? I did not have too much time to do research but was able to find this: http://www.macgurus.com/productpages/guides/PortMultiplicationGuide.php It is mentioning 225MBps (~1,7Gbps) which would result in original authors setup 225MBps/5 = 45MBps parity sync speed. I'm getting right now with 10 disks with no bus limitation 75MBps parity sync speed so that is not a dramatic difference and definitely not too bad seeing what most of the users are reporting.
June 27, 201214 yr Given that the unRAID CPU ... ... so a couple of fans and you're set. Regards, Stephen The math seems to work but I've just seem to have seen serious heat issues when everything is stuffed into an old desktop case. Either that or the thing roars from all of the fans. As long as you set it up right they can be near silent. I use this case: http://www.newegg.com/Product/Product.aspx?Item=N82E16811129021 I use two 5 in 3 drive cages that take up the top 2/3s of the case. I disabled and blocked the front fan on the bottom of the case so all air is pulled through the drive cages by two 92mm fans mounted on the back of the cages. Core i3-2120 is cooled by the stock Intel heatsink. Exhaust is a 200mm fan on the top of the case, one 120mm on the back of the case and one 120mm fan on the side of the case. Drives all stay below 35 degrees and the CPU idles in the 20s; 40 under full load. These are all well within normal operating temperatures and this is in a house in the summer with no central air conditioning. And the server is barely audible unless you focus on trying to hear it.
June 28, 201214 yr ... I had an 8-bay (2x4 drive port multiplying) config -- and that's definitely true. I'd get stutter on playback if I happened to hit 3 drives on the same PM supported card channel. Sometimes stutter even with 2 drives at the same time. Never with 1 drive. Hi Chuck, It sounds like you were in Command-Based-Switching (CBS) mode, as opposed to Frame-Based-Switching mode (FBS) (please look them up; I'm terrible at explaining tech stuff). You would never want to use CBS when multiple moderate-to-high-bandwidth streams are involved. For a real-world test (I just happened to be messing with my PM enclosure), I did the following: seektest -b128k -n512 /dev/sdX on 4 PM-connected drives simultaneously. (seektest is a little hack of mine) [on each drive] performs 512 random-access reads of 128KiB each (total data = 64MiB) across the full drive surface (no "short-stroking") The entire test (all 4 drives) completed in 10.2 secs. So that would equate to 4 simultaneous streams of ~50Mbps each. (I believe that 48Mbps is a commonly accepted upper limit on BluRay bandwidth spec). The drives were 3x5K3000 and 1x7K3000 (all Hitachi 2TB), in a SansDigital TR4M+ (SiI 3726 port multiplier), connected to a single port on a Marvell 9125-based PCIe x1 v2 card. I don't use unRAID, but this was on a HP N40L running stock 2.6.37.6 Linux. Doing a straight read-transfer (sequential) test with the same setup, total length (per drive) of 640MiB with a buffer (transfer) size of 128KiB got transfer rates of 60, 58, 58 & 57 MiB/sec (simultaneous). This test would simulate a unRAID parity-check, I believe. I have not yet tried a similar test, but using two 4-drive PMs, each connected to the same (above 2-port) card. I've seen some "rumors" that it just won't handle 2 PMs at once (I dont' believe that); I also don't expect it to do 230+ MiB/sec on each PM. In closing, a "warning": Getting the right combination of OS/card/PM/bus is not a "formula"; I got lucky. Ie, YMMV/YMWV! --UhClem "We're all bozos on this bus"
June 28, 201214 yr Given that the unRAID CPU ... ... so a couple of fans and you're set. Regards, Stephen The math seems to work but I've just seem to have seen serious heat issues when everything is stuffed into an old desktop case. Either that or the thing roars from all of the fans. As long as you set it up right they can be near silent. I use this case: http://www.newegg.com/Product/Product.aspx?Item=N82E16811129021 I agree, I'm using this case: http://www.newegg.com/Product/Product.aspx?Item=N82E16811146072 with a 4 in 3 adapter in the 3x5.25 inch bay area and it is quite quiet. Its a great case for an 8 drive build and with a hot swap 4 in 3 module it would be good for a 12 drive build too. I use two 5 in 3 drive cages that take up the top 2/3s of the case. I disabled and blocked the front fan on the bottom of the case so all air is pulled through the drive cages by two 92mm fans mounted on the back of the cages. Core i3-2120 is cooled by the stock Intel heatsink. Exhaust is a 200mm fan on the top of the case, one 120mm on the back of the case and one 120mm fan on the side of the case. Drives all stay below 35 degrees and the CPU idles in the 20s; 40 under full load. These are all well within normal operating temperatures and this is in a house in the summer with no central air conditioning. And the server is barely audible unless you focus on trying to hear it. I blocked the inlets on the bottom of the case in order to get all the inlet air to be drawn in through the drives. Regards, Stephen
June 28, 201214 yr Author I agree, I'm using this case: http://www.newegg.com/Product/Product.aspx?Item=N82E16811146072 The trouble is that I'm trying to build an uber cheapy server. Starting with a $100 case and then added a powersupply, mobo, PCI for extra drives is going to get me into the cost of a prebuilt system (ie, north of $500). I'm trying to do this in a two or three year old desktop that will cost me about $50. Then I can spend on the OS & drives.
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