ReadyNAS Update

[VLSmooth]

In response to Bob's IM at work, I'm waiting for a memory RMA to arrive for my ReadyNAS before it has a chance of working.

The Infrant forums thread has the details. Go go ASCII art kernel debug error messages!

[Jonathan]

• You are increasingly communicating in lists instead of paragraphs.
• This is generally considered bad style.

[VLSmooth]

Why do you think lists are "generally considered bad style"? I find it an efficient way to quickly and clearly convey information.

[VLSmooth]

Got the ram, did another factory install, and now it works like a charm now.

Currently uploaded and crc32 checked 251 gigabytes (1293 files, 66 directories). Download/upload speeds are 30+/10+ megabytes per second without jumbo packets (my main computer's silly XP installation is missing "Network Connections" so I can't change my MTU).

I'll toss more on later, I need to organize/rename more stuff.

ps. I tried all the steps here to no avail. I'll probably need to reinstall windows, but I'm too lazy to do that now.

[Jonathan]

Why is there such a big discrepancy between up and down?

[VLSmooth]

I'm not exactly sure, but if I would hazard a guess, it's due to the RAID5 and/or journaling. Perhaps XORing and writing to multiple disks isn't parallelized as well as reading from multiple drives?

[VLSmooth]

Also, they recently released a fanless version, Repetoire. Grr, I might've gotten that if I knew. Then again, the NV is pretty darn quiet.

[VLSmooth]

Yep, according to StorageReview's article here, RAID5 definitely plays a role in the read/write speed discrepancy.

Quotations split up to mitigate wall-of-text syndrome.

For reads, striping with parity can actually be faster than striping without parity. The parity information is not needed on reads, and this makes the array behave during reads in a way similar to a RAID 0 array, except that the data is spread across one extra drive, slightly improving parallelism.

For sequential writes, there is the dual overhead of parity calculations as well as having to write to an additional disk to store the parity information. This makes sequential writes slower than striping without parity.

The biggest discrepancy under this technique is between random reads and random writes. Random reads that only require parts of a stripe from one or two disks can be processed in parallel with other random reads that only need parts of stripes on different disks. In theory, random writes would be the same, except for one problem: every time you change any block in a stripe, you have to recalculate the parity for that stripe, which requires two writes plus reading back all the other pieces of the stripe! Consider a RAID 5 array made from five disks, and a particular stripe across those disks that happens to have data on drives #3, #4, #5 and #1, and its parity block on drive #2. You want to do a small "random write" that changes just the block in this stripe on drive #3. Without the parity, the controller could just write to drive #3 and it would be done. With parity though, the change to drive #3 affects the parity information for the entire stripe. So this single write turns into a read of drives #4, #5 and #1, a parity calculation, and then a write to drive #3 (the data) and drive #2 (the newly-recalculated parity information). This is why striping with parity stinks for random write performance. (This is also why RAID 5 implementations in software are not recommended if you are interested in performance.)

Another hit to write performance comes from the dedicated parity drive used in certain striping with parity implementations (in particular, RAID levels 3 and 4). Since only one drive contains parity information, every write must write to this drive, turning it into a performance bottleneck. Under implementations with distributed parity, like RAID 5, all drives contain data and parity information, so there is no single bottleneck drive; the overheads mentioned just above still apply though.

[moonunit]

In response to Bob's IM at work, I'm waiting for a memory RMA to arrive for my ReadyNAS before it has a chance of working.

I'm sure I missed it, but is there a thread on why you decided to go with the ReadyNAS instead of a small Linux Computer. I was considering a RAID setup, with a micro-computer with Linux and LVM, etc. Of course, you do get the RMA support if things break, which is also nice.

What is your current solution for backups? Do you have another few drives laying around in your main computer for weekly backups, etc?

Peace
-Trev

[bob]

When you can afford to get a custom system made for the purpose, rather than building and messing with a linux system you don't want to deal with, then you get the custom system.

[VLSmooth]

Ack, for some reason I forgot about this thread.

I'm sure I missed it, but is there a thread on why you decided to go with the ReadyNAS instead of a small Linux Computer.

Pretty sure I posted it before the great forum rewind of 2006 (TM), but just in case I didn't, the reasons were primarily convenience and cost.

The ReadyNAS NV is specially tailored for redundant storage, small, low-power, quiet, and generally well-designed. Infrant's X-RAID approach allows upgrading/expansion without having to backup everything, which is simply a blessing. Infrant also has pretty active forums and continues to improve.

Of course, I tinkered with the idea of building a system from scratch, but found the dollar savings to be miniscule (hardware RAID-5 cards are NOT cheap). The potential setup and configuration headaches weren't exactly thrilling either.

What is your current solution for backups? Do you have another few drives laying around in your main computer for weekly backups, etc?

I don't have a convenient way of backing up ~873 GB of RAID-5 data, so my backup solution is just to put things on the NAS. Yes, the NAS controller itself is a single-point of failure (stupid RAM). However, the ReadyNAS NV does support one-button backup of a special backup share to a USB hard drive if I so desire.

Hope that helps,

[Jonathan]

I just installed Cygwin on Amber's computer to back it up onto my desktop Linux box using rsync. Of course, I am only concerned with ~15GB of music, not a terabyte of video, so my backups fit nicely on a single drive.

Don't use the rsync compiled for MinGW; Cygwin is the way to go here.

I left a DOS batch file on her desktop that runs a Cygwin shell script that calls rsync, so she can run it whenever she likes. I might look into using Windows Scheduler or something to automate it at some point; it depends on what she wants.

[moonunit]

What is your current solution for backups? Do you have another few drives laying around in your main computer for weekly backups, etc?

I don't have a convenient way of backing up ~873 GB of RAID-5 data, so my backup solution is just to put things on the NAS. Yes, the NAS controller itself is a single-point of failure (stupid RAM). However, the ReadyNAS NV does support one-button backup of a special backup share to a USB hard drive if I so desire.

Hope that helps,

I guess my thoughts were more about the accidential erasure of data, that even a zSeries mainframe couldn't stop you from doing. I hate it when I accidently erase files. There is no undelete usually! Also, say there is a rogue program / virus / spyware that deletes all .mp3s and .avis, then what do we do?!

I see what you mean about the hardware-RAID solution. The product sheet does say that, but I remember seeing Hardware-RAID claims a while back, and probably should just check on these guys.

Another issue for me is both software and hardware connectivity to the box. Ethernet is entrenched, but technology always seems to move faster that I can predict. On the software front, maybe I want a streaming audio server that supports a new protocol that all of the new camera phones are supporting.

The size is awesome! I'k still wavering on my personal trade-offs, and if I really need "all of the functionality" that much be needed.

I do love ease of HD expandibility, very much so! But where to back it all up?!!

I'm in the few-hundred gigabytes of data range, definitely not near 1TB yet.

Som many questions. What is the maximum storage per device on an SATA-II HD?

Repetoire looks great, but I don't have a media center right now. Maybe I could put it under my monitor.

Have a great one!
-Trev