What is the risk here?
For example, if I use RAID5, my disks have already been initialized with either the write or clear method. What am I risking here. What issues have people encountered when they have not done this?
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What is the risk here?
For example, if I use RAID5, my disks have already been initialized with either the write or clear method. What am I risking here. What issues have people encountered when they have not done this?
Initialize:
This option is available when creating an iSCSI (I) or Fibre Channel (FC) volume. It is here for security reasons. The volume will be initialized after the creation process. There can be only one volume being initialized at any one time. If there are more volumes to be initialized, a Waiting indicator will appear near the one(s) enqueued. Using the button next to the indicator you can send the initializing volume to the back of the initialization queue. Every volume that is waiting for initialization in queue can also be sent to the back of queue.
Initialization is made for data protection. Basically when you initialize your volume you fill it with zeros, then when you write over the volume the space that has no data will be protected.
Its a low level format, and many big companies are using this, EMC for instance force you to do it. It’s a good feature. It may take time for big volumes, but it’s so important..
I guess my point is that it's sort of redundant right? If disk blocks underneath the volume have already had zeros written across them - then why do it again?
I'm trying to understand what are the real world implications. E.G Customer A didn't init a volume and had some bad things happen.
Dear enealDC,
The initialization here is not redundant, as initializing the Logical Volume will be on file system level, while the RAID is on the block level. Our tests shows that initializing logical volumes are more stable.
Regards,
SJ
should i enable this when expanding an existing iSCSI volume? (eg 100gb)
will it initialize only the new additinal volume (eg 50gb) or the whole lot and wipe my current data? (eg 150gb)
Only the initialized amount.
Hi Todd,
I, too, am not getting it! :o Wht exactly is the advantage of zero'ing a iSCSI or FC volume? If I put toghether a new storage, there're probably only zeros on the drives anway, or any other pattern, that the manufacturer chose.
What, other than detecting any problematic sectors on the volume, could this be good for? And why only the initial amount and not the subsqeuent ones.
Seems that I could just create a 1 GB iSCSI Volume and have it zero'ed and afterwards I go ahead and grow it to the size I initially wanted?
This confuses me…
Cheers,
budy
You dont have to use this function and this was demanded by many users even EMC products will force you to use this function when creating an iSCSI LV. Initialization fills volumes with all zeros. It is for security reasons as uninitialized volumes may lead to data corruption. Also some drives may not be new and we would not be able to tell from the sw end, so this is a good reason to have it, again you dont have to use it.
Hi Todd,
the technical benefit still escapes me though… The only thing I could possibly think of being worth to be zeroed out are the areas where the FS would store its data, but the rest of the LV I wouldn't care about.
This also plays nicely with the statement that one wouldn't have to zero out the areas where the LV would have been grown to.
Cheers,
budy
We provided some information about this from link below in the section of File IO with initialization, this is similar to a low level format.
http://kb.open-e.com/entry/342/