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Showing posts from August, 2012

Fixing out-of-space Storage Spaces pool

If when creating a Storage Spaces volume you used a "thin provisioning" feature, then sooner or later you face the situation when physical space for your virtual hard drive is over. Then, if you need to write data, the Storage Spaces driver can no longer allocate a new slab; it just disables the virtual drive, i.e. makes the drive offline, interrupting the last write operation. To resolve this problem you need to add disk space to the pool. However, it is not always possible, for example in case of four-disk array you would have to bring four disks at once. So if for some reason you cannot add disks immediately but you need to get access to the data, you can go to Windows Disk Management, make the disk online again, then delete unnecessary files and folders. For a while this should be enough but you will have to add disks eventually.
However, this doesn't always work. It may happen that whenever Windows Disk Management brings the disk online, the Storage Spaces driver im…

Write speed in Storage Spaces

People note that write speed on mirror or parity volumes in Storage Spaces is slower as compared to a traditional RAID1 or RAID5. Indeed, parity and mirror volumes of Storage Spaces are not identical to a regular RAID1 or RAID5 in terms of maintenance costs. The ReFS driver that manages the filesystem structure on the Storage Spaces volumes must also calculate checksums over data to avoid the write hole issue.

Getting used to it...

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4x Lowvel erasing 4x test hard drives in parallel during preparation to another Storage Spaces test.

Cost-saving

They say that when Storage Spaces is officially released and when it wins user's confidence the prices of NASes like Drobo, QNAP, or ReadyNAS will drop. We suppose that it is quite possible because a bunch of external USB 3.0 disks connected to a USB 3.0 hub and winded together using a sticky tape may become a cheap and effective alternative.

Let's compare these two options based on the NewEgg prices

$528 QNAP TS-419PII-US
or
$535 NETGEAR ReadyNas Ultra 4-bay

against the set of
$25 Rosewill RHB-610 (RIUH-11001) 4-Port USB 3.0 hub
$164 4x SAT3510BU3 3.5" USB 3.0 SATA Enclosure w/ Fan
$1 Duct Tape
for a total of $190

All additional functions that are available in QNAP or other NASes for example torrent downloads or the capability to access the data via a network from multiple computers, Windows 8 can provide as well (though you may need to use free software like uTorrent)

Storage Spaces complaints

At homeservershow we came across a pcdoc's story telling about Storage Spaces failure. However based on the description we may suppose that in this case Storage Spaces worked properly, a culprit of failure was a HPT 2680 controller. A RAID controller beeps only in two cases: when the controller itself failed or when one of the disks connected to it failed. If a Storage Spaces pool placed on the disks connected to a controller is about to fail, a controller will not know about it.
Since no drivers were installed, it doesn't make sense to expect a detailed diagnostic from the controller. We can assume that disks were not guilty of a failure, since checking did not detect anything and the disks had good SMART characteristics. So the only remaining possibility is that a controller failure occurred. It is impossible to point out the reason of failure without access to the controller itself. Having looked over user's comments on NewEgg we may assume that it was overheating issue.…

Storage Spaces Recovery project

Nowadays we are busy developing the tool that will be able to recover data from a deleted Storage Spaces pool. The recovery should be based on only the data stored in the pool, not on a Storage Spaces data base.
We have understood already that the tool will demand quite stern system requirements and will be slow since two passes over disks will be needed. Additionally it is required that all the data is read for each pass. The chance to get an absolutely correct recovery solution is not very good, at least on this stage of design and testing. It is not ruled out that about ten percent of data will be lost irreversibly.
We plan to produce the first preview version of the tool in the end of this year (2012).  The web site for the project is here.