eva reconstrction with rss

[samaoas]

i need some information on rss.
eva creates rss using 8 disks and remaining with 6-11 disks. for example i have 24 disks in a disk group with single protectoio. so 3 rss with 8 disks will be created. above this when i create a vraid 5 virtual disk,the virtual disk is created in all three rss with each rss as 10MB (8MB data and 2MB for parity).
in this scenario, if two disks fails in different rss,, then i dont loose data. if 2 disk are failed in the same rss,, then i loose all the data and it cant be recoverable.
in the above setup, how raid 1 virtual disk behaves. how the data is written in raid 1.

[Uwe Zessin]

VRAID-1 data is written to two different physical disk drives, e.g. at index 0+1 or 2+3, ... within one RSS.

[samaoas]

can you explain me something more in detail. what is the advantage of creating raid 1 instad of raid 5. what is mean by index. can you give some examples on this.

[Johan Guldmyr]

hi, is all about the probability of two drives failing at one.

with vraid5, 2 disk out of 8 causes data to be lost

with vraid1, 2 disks in one pair causes data to be lost

with 24 disks, you would have 12 pairs then for the vraid1 disks.

supposedly, these 24 disks are housed in two disk enclosures?
then if everything is done right, you should have the two disk in each pair on separate shelves

[Oscar_Maimó]

Within a Disk Group the RSSs are formed by 6 to 11 disks, according the number of disks on your DG. If you loose 1 disk you will loose all data in VRAID 0 LUNs. If fou loose two disks in the same RSS set then, you will loose all your data in VRAID 5 LUNS on this RSS. If this disks are a pair, then you will loose all data on this RSS.