Best eSATA JBOD? 210
redlandmover writes "I already have an HP Media Server (upgraded processor, and memory) that has already been upgraded internally to 3.5TB. I'm sure everyone already has their favorite backup solution (RAID, WHS, a billion external hard drives, etc). My question is: what is the best JBOD (Just a Bunch of Drives), eSATA-connected, external hard drive enclosure? (Preferably, at least 4 drives.)"
Why? (Score:2, Informative)
I think Linux and Windows can both do this quite easily in software... but why bother? JBOD is the worst of both worlds when it comes to storage arrays. You have all the risk of losing everything if one drive dies, without gaining the performance benefits that RAID 0's striping gives you. Hard disks are cheap enough for a 2TB RAID 10 array to be affordable.
Yes this was quite a predictable comment, but someone had to say it..
If you need more than ten disks, go for cheap SAS (Score:5, Informative)
You can get an external (4-port, but acts like one big 1.2 GiByte/s pipe) SAS RAID card for less than $500 that will allow you to make multiple RAID sets of up to 32-disks in a set using true hardware RAID 5,6,10, etc. You can even get a battery backup unit for the RAID card cache for $100 (priceless on critical DB systems).
An external SAS card allows you to connect over a hundred drives through one connection using SAS expanders (some cards support up to 256 devices). Some external SAS RAID/JBOD cards have two SFF-8088 connections, for eight SAS lanes total. That's 2.4 Gigabytes/sec raw. At that rate, it's your PCI-e bus that's usually the bottleneck.
A lot of SAS expanders are expensive, but Chenbro has some ones for $300 that spread one x4 lane SAS cable into 24 or 32 cables, plus they can be daisy-chained for more storage. Then, buy a nice 24-slot Supermicro 4U chassis with dual-redundant power. That's a little less than $1000. All you need is the Chenbro expander in the chassis, no need for a motherboard.
If you're really cheap, you can use a cheaper $150 external SAS JBOD-only card, but hardware raid really is a must if you have a lot of storage. Plus, a hardware raid can use write-back cache, since it has effectively non-volatile RAM using the battery backup unit. And no, a UPS is NOT a replacement for NVRAM... Has your system ever crashed for any reason or hung for any reason? I've never had a RAID card hang or crash.
So, basically, besides the external SAS card, you have:
24-slot chassis with redundant power: $1000
chenbro SAS expander: $300
cables: depends
That's about $60/slot, plus you have redundant power (and an upgrade route to dual-redundant controllers). You can scale this to hundreds of terabytes, too. Over a petabyte if you have multiple controllers (with raid array rebuilding on one card not affecting rebuilding on another).
Re:Why? (Score:4, Informative)
No that's not correct. JBOD is just that. Just a bunch of disks. Has nothing to do with redundancy (or lack of redundancy). What you do with them is completely up to you. You can implement a RAID-Z with them on solaris (which is actually faster on my Enterprise-class disk array than the built-in RAID-6 in hardware!), Linux RAID-5, RAID-10, or whatever. Except for issues of battery-backed caching, I have come to the opinion that for most low- to middle-end storage needs, a large JBOD and software RAID is the way to go.
Re:I stopped reading the summary (Score:3, Informative)
You'll be crying when you rebuild that raid and two disks fail at the same time (happened to me). No - raid isn't a backup solution.
Re:I stopped reading the summary (Score:3, Informative)
RAID 1 + swapping out/rebuilding a mirror disk periodically is a perfectly reasonable backup solution.
Sure, if you're retarded. I was going to say it was ok for home, but no, that's just stupid. Even a batch job that tars a bunch of directories onto a second HD works better (and no additional hardware either).
Re:The best ESATA isn't really ESATA at all. (Score:3, Informative)
Make sure to find a port multiplier with FBSS (FIS-based switching) support. Also make sure that your SATA controller supports this feature. Otherwise, there can only be one outstanding command for all attached disks, and performance will be abysmal.
Re:I stopped reading the summary (Score:5, Informative)
Re:Drobo (Score:1, Informative)
See the Drobos [drobo.com] at the linked page. No eSATA, but perhaps you can get an eSATA -> firewire 800 or iSCSI (sp?) dongle. The best part about them is ease-of-use.
and the worst part is that their users all seem to be morons who don't realize they've been ripped off by slick marketing.
Re:Why? (Score:3, Informative)
No that's not correct. JBOD is just that. Just a bunch of disks. Has nothing to do with redundancy (or lack of redundancy).
This is incorrect. JBOD is similar to RAID 0 without striping, allowing one to use disks of dissimilar size. There are some RAID controllers that will incorrectly refer to presenting physical drives directly. However most RAID will correctly present a JBOD as a single logical volume.
Please refer to the Wikipedia article on RAID [wikipedia.org].