I've been reading up on FreeNAS and RAID Z, and one of the things  is that you shouldn't use ZFS (or more specifically, RAID Z) on a machine without ECC RAM. I'm wondering what the reasoning behind this is. Is this an issue with RAID Z specifically? Is there any particularly heightened risk from not using ECC RAM with ZFS vs other file systems? Or is this just a general concern about corrupt memory spreading to a filesystem which would otherwise have corrected the error thanks to its ?
122342
I have a new server and am planning to upgrade the paltry 2 GB of memory to the maximum of 16 GB. (Theoretically 8 GB is the limit, but empirically 16 GB has been shown to work.)   advise that ECC memory is not that important, but I'm not so sure I believe this.     I've installed  and am planning to add ZFS volumes as soon as my new hard drives arrive.   Would it be stupid to skimp and get non-ECC memory for a ZFS-based NAS?  If it's necessary, then I'll bite the bullet, but if it's just paranoia, then I'll probably skip it.  Is there any reason ZFS or FeeeNAS specifically would require ECC memory, or suffer especially when running on a system using non-ECC memory?
101282
I apologize if this question has been answered previously.  I've checked through the "similar titles" but haven't exactly had any luck.  I'm aware of the problem and I know the solution, I simply don't know how to implement the solution properly.  Any help would be greatly appreciated.  What I'm experiencing is a SMART failure 05 and I'm being warned that a disk failure is imminent.  My old partitions is what is causing the problem and the solution is to skip over the bad sectors via a new partition.  I have a 100gb hard drive, and I think it's safe to say that the first 20gb are borked in this regard.  How do I set up a partition outside of these first 20gb?  Would I designate this as "free space"?  Or something else?  Please be detailed (e.g. screen shots), I'm fairly computer literate but I'm a beginner when it comes to Ubuntu 12.04.  Thank you for your help!
73526
briefly list the format of the free command, noting that buffers is kernel memory that must be written out to disk and cache is file data that does not need to be written disk.  On my system, unlike most times I have run free, buffers occupies over 10% of RAM.  Usually, buffers are a small, almost token, value.    My question is, what exactly is in the area called buffers?  Can I look for it with lsof?  Does it consist of open file regions that have not been flushed?  Is it memory mapped file regions?  What is it?  The system runs well and little swap is used, so performance is fine.
2113
So, let's say your server had 6 healthy hard drives.  A drive fails (will not mount/detect, drops out of raid with errors) or is failing (SMART getting worse, etc).  You need to swap out the bad drive.  When you open the case you see.. six identical hard drives.  How can you tell which one is no longer healthy/mounting/functioning?  System would be linux, most likely ubuntu server, using at most simple software RAID.  The hard drives would be SATA and connected directly to the motherboard. (no raid controller)   I don't want to randomly disconnect drives until I pick the correct one.  The drives all appear identical to me; I imagine there is some common way to identify which drive is which that I am unaware of.  Does anyone have any pointers/tips/best practices?  Thanks!  EDIT: I had wanted this to be 'generalized' in a hand-wavy sort of way, but it just came off as 'incomplete' and 'horrible'.  My bad!
97566
from the above pic, you can see we have 3191 RAM free, but at the same swap is also using about 661 bytes. why it is occurring ? can any give a glance regarding this.  Thanks
25128
I'm still new to ZFS. I've been using Nexenta but I'm thinking of switching to OpenIndiana or Solaris 11 Express. Right now, I'm at a point of considering virtualizing the ZFS server as a guest within either ESXi, Hyper-V or XenServer (I haven't decided which one yet - I'm leaning towards ESXi for VMDirectPath and FreeBSD support).   The primary reason being that it seems like I have enough resources to go around that I could easily have 1-3 other VMs running concurrently. Mostly Windows Server. Maybe a Linux/BSD VM as well. I'd like the virtualized ZFS server to host all the data for the other VMs so their data could be kept on a physically separate disks from the ZFS disks (mount as iscsi or nfs).  The server currently has an AMD Phenom II with 6 total cores (2 unlocked), 16GB RAM (maxed out) and an LSI SAS 1068E HBA with (7) 1TB SATA II disks attached (planning on RAIDZ2 with hot spare). I also have (4) 32GB SATA II SSDs attached to the motherboard. I'm hoping to mirror two of the SSDs to a boot mirror (for the virtual host), and leave the other two SSDs for ZIL and L2ARC (for the ZFS VM guest). I'm willing to add two more disks to store the VM guests and allocate all seven of the current disks as ZFS storage. Note: The motherboard does not have IOMMU support as the 880G doesn't support it, but I do have an 890FX board which does have IOMMU if it makes a huge difference.  My questions are:  1) Is it wise to do this? I don't see any obviously downside (which makes me wonder why no one else has mentioned it). I feel like I could be making a huge oversight and I'd hate to commit to this, move over all my data only to go fubar from some minute detail I missed.  2) ZFS virtual guest performance? I'm willing to take a small performance hit but I'd think if the VM guest has full disk access to the disks that at the very least, disk I/O performance will be negligible (in comparison to running ZFS non-virtualized). Can anyone speak to this from experience hosting a ZFS server as a VM guest?
55543
First, the situation:  I've got a Linux computer with two eSATA drive bays that accept removable SSD drives.  I'm trying to write a little GUI application that makes it easier for the user to mount/unmount/format/backup/etc the drives that he puts into these bays.  It all mostly works.  One small problem, however, is that I don't know how to find out any information about what's on the inserted drive(s) until after the drives have been successfully mounted.    So, for example, if the user inserts a drive that I can't mount (e.g. because it is unformatted, or formatted with an unexpected filesystem), all my app can say about it is "Drive failed to mount".  This isn't very satisfactory, because if the drive is unformatted, the user will probably want to format it... but if the drive contains data from an unrecognized filesystem, the user will probably NOT want to format it.... or at least, I want to be able to warn him that by doing so he'll be erasing potentially valuable data.  So my question is:  is there any method for querying some basic information (especially filesystem-type) from a drive that doesn't require that the drive already be mounted?  Or do I just have to try to mount it with various known filesystems until one of the mount attempts succeeds, and give a vague "be careful" message if none of them do?  In case it matters, the paths I use to mount the drives in the drive bays are:  /dev/disk/by-path/pci-0000:00:1f.2-scsi-2:0:0:0 /dev/disk/by-path/pci-0000:00:1f.2-scsi-1:0:0:0
100533
I recently purchased a Dell R730xd that came with an H730 RAID card. I would like to bring an existing 6 disk ZFS pool to this server as well as create an additional 6 disk hardware RAID.   Is it possible to configure an H730 RAID card to operate in both HBA and RAID mode simultaneously? And then only manage 6 of the disks in a hardware RAID and allow the OS to manage the remaining 6 disks in a software RAID?  If not, can a Dell R730xd use both an H730 RAID card and an LSI 9207-8i HBA card simultaneously? Would you simply plug one SAS cable from each card into each part of the Backplane? Will I need to purchase any new cables to connect the LSI 9207-8i to the backplane in my R730xd?  Is there a better card to use for ZFS in an R730xd using spinning disks than the LSI 9207-8i?
103023
I use Ubuntu 12.04 on a home server. There are 5 hard drives: one SSD with the OS and 4 HDDs (Samsung HD204UI) configured as a RAID5 using mdadm.  I don't need the RAID very often (say, about once per day in average); it contains multimedia data and some backups, so I decided to put the drives to standby most of the time.  I configured the drives to automatically spin-down after 20 minutes using hdparm, here /dev/sda as an example:  hdparm -S 240 /dev/sda   The output of the command confirmed this:  /dev/sdb:  setting standby to 240 (20 minutes)   But the problem is that the drive spins down after about 5 seconds (instead 20 minutes) after the last access, and  hdparm -C /dev/sdb   displays:  /dev/sdb:  drive state is:  standby   Why doesn't the drive wait the 20 minutes as configured? Does it have something to do with the RAID setup? (I don't think so...)  This very short timeout is problematic since it is a RAID5 and when I access a file, it is spread block-wise around the four drives. Since drive 1 isn't needed when drive 2 is read, it went asleep when it will be used the next time (after drive 3 has been read from). So the drives keep spinning up and down the whole time resulting in a throughput near zero.  For the people being concerned about the life of my drives: It will be no problem that the drives are spinned up and down once a day in average since I prefer saving energy and heat over health of the drives (I use RAID5 and the content isn't very important).
69339
I'm building a new computer over the summer. I'm fairly competent in computer hardware, and am thus building the computer from scratch. I have everything planned out, but I was wondering about RAID.  I  earlier, but now that it's pretty clear that RAID 1 isn't really that great, I think I'll go with cloud-backup instead of disk-redundancy. However, I still face a choice: use two 1 TB drives as two 1 TB drives, or combine them into a RAID 0 striped array.  Is there any performance gain at all? I know that if one drive dies, everything is gone, so is the performance gain worth it? I'm building a pretty advanced computer, with SLI video cards and a fast CPU, so I'm thinking RAID 0 would give me some good hard drive performance. From your experience, is RAID 0 viable?
56843
I am wanting to replace my Operating sytem hard drive with 2 SSD drives. Well possibly just 1 but I am curious about doing 2 in a RAID-0 setup for even more improved speed.  What exactly would I need to run 2 SSD drives in a raid0 setup?
88136
I usually use mount to check which filesystems are mounted. I also know there is some connection between mount and /etc/mtab but I'm not sure about the details. After reading  I get more confused.  My question is: How to get the most precise list of mounted filesystems? Should I just use mount, or read the contents of /etc/mtab, or contents of /proc/mounts? What would give the most trustworthy result?
20723
If computer RAM was to be non volatile like other persistent storages, then there would be no such thing as boot up time. Then why is it not feasible to have a non volatile RAM module?
7198
What lifetime can be expected of the typical hard disk? Or are there big differences between different types? And does it make a difference if it is used heavily instead of never being connected to system (for example serving as a backup medium)?
91079
My motherboard (HP Pavilion s3000y) only supports 2GB of RAM max. Which means that I can only allocate 1GB for running VMs, and applications that use a lot of RAM are slow (such as games and Visual Studio).    Is it possible to use a storage disk such as a USB drive as RAM?    Or if not, can VirtualBox use a drive as RAM for VMs?
9112
I have just set up my new system by creating three partitions on a whole hard disk (/boot, /home, swap and /). I saw  article and now I am getting those errors and the system provide me with some options: (I to ignore, S to skip mounting or M for manual recovery).   I am forced to choose skip mounting because I don't know what manual recovery is. Despite the error I get I think that the system boots okay because I can use the system but this error is very annoying.
57473
When I assembled my current system two years ago, I bought a Crucial M4 128 GB SSD, which was truly worth its price and I bought a Samsung EcoGreen 2 TB HDD, primarily for storing large media data like movies etc. This was likewise the last time being up to date about the actual market situation.  I've just been checking out the most recent releases on the hard disk market, because my EcoGreen gave up a couple of days ago.  I just grabbed dat cheap EcoGreen, because HDD's in 2011 were pretty cheap anyways. Green was in and the market was just flooded with a vast variety of different models being worth their price. There was a lot of silly stuff out there either: green monitors, green power supplies, even green USB flash drives. Despite the EcoGreen gave up after 2 years, I don't regret buying it at all. It's still the cheapest disk space, I've ever bought.  I might get a new EcoGreen, because its 3 years warranty didn't expire yet, nevertheless I searched for potential ones to buy, which might have released in the past two years. And pretty early I found the .  Here what Western Digital writes about their product:        Compatibility: Desktop hard drives are not always tested for compatibility in NAS and can present problems during integration.    Reliability: Most desktop drives are not designed for the high operating temperatures or for 24x7 operating environments making them   less reliable when used in a NAS system.    Error recovery controls: Desktop drives are not traditionally designed for RAID environments and have controls that prevent the RAID   controller from assisting in the event of an error which can cause the   hard drive to drop off the RAID after a period of time.  Rebuilding a   RAID often requires several hours and can have a significant impact on   downtime and productivity.    Noise and vibration: Typically designed for single drive applications, average desktop drives are not optimized for multi-drive   systems which have higher noise and vibration levels. When these   drives are added to a NAS, the additional vibration can reduce the   reliability and life span of the drive.      Since I always thought a system's overall power consumption is impacted by the HDD power consumption at least, I'm suspicious if this might not be another hype? EcoGreen's were about 0.5W more efficient over desktop HHD's, or am I wrong informed? Or am I completely wrong and EcoGreen was not even a hype? I have to admit, that purchasing the EcoGreen already made me expect not such a huge benefit from getting a green one. It's been solid, but nothing special.  What do you think about this?