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EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

DCESStorage_1
Occasional Advisor

EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

EVA8400 - "Disk drive failure protection" complains:

Actual level: None
(Requested level not available)

even though 2 largest 450 GB drives worth of free space available. We always had "Single" level of protection.

Currently - leveling taking place after Group'ing of two new disks (just replaced two failed HDs).

Any thoughts why this we are not getting back to "Single" level protection ?

Thanks
11 REPLIES
Sivaramakrishna_1
Honored Contributor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

Nothing to worry i think. Everything will be normal once levelling completes.

You may aware of that Single protection takes 2 Drive size capacity. After 2 Drive failure the free space may not be available so controller will make Protection to None.

As Requested is already "Single" once levelling completes, It will move back to "Signle" on Actual protection.

This is common and nothing to worry. Just wait till levelling completes and update the status
Johan Guldmyr
Honored Contributor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

Might be worth noting that just because your disk level protection is down to none, you don't have less redundancy, you just have less available space because you are grouping in two new disks.
john_347
Regular Advisor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

Hi all,

I thought best practice stated that you should leave 5Gb of space per disk in each disk group. The system uses that spare space to allow for levelling before it goes into the sparing. THat is if you don't use 100% of the diskgoup space.

regards
Johan Guldmyr
Honored Contributor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

It sure does speed up things to leave a bit of free space yes.
Uwe Zessin
Honored Contributor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

One of the best practices guide says:
"Leveling and reconstruction can be performed with a minimum of 5 GB of free space per disk group."

but that is only for static environments. And they recommend to leave even more free capacity for a so-called PDM (Proactive disk management) operation - e.g. the manual ungroup of a suspected disk drive.

To me, that sounds you want to set the so-called "protection level" to double (2). That reserves capacity for a PDM (1) plus capacity for a reconstruct (another 1).
.
Virtual Craig
Occasional Visitor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

This is normal - you had two disks failures - the first will have taken the 2 x 450GB you had free (free space always taken first) then the second failure would have taken sparing.

After the leveling completes all will be back to normal.
DCESStorage_1
Occasional Advisor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

Thanks to you all guys. Things gotten back to stable after about a week - for the levelling to finish (two disks, ours is a fairly busy EVA).

Appears - best thing to do is - add a pair of new disks to the disk-group, then immediately remove the indicted/about-to-be-failing pair of disks. So, leveling can possibly happen between failing-pair and newly-added pair. Rather than, leveling amongst 170 or so disks in that diskgroup (which took about 1+ week to finish in our environment!)

Any thoughts ?

Thanks
Sri
Johan Guldmyr
Honored Contributor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

Just make sure the disks aren't in the same RSS.
DCESStorage_1
Occasional Advisor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

From what I understand - disks/data is replaced in pairs. If you are only replacing one failed disk at a time, how do you avoid/minimize leveling time/pain ? (obviously, we don't have dozens of ungrouped disks sitting around, to add a pair for a single indicted disk. Soon or later you will run out of un-grouped/free disks)

Obviously, if we wait for second failure/indictment to show-up, it may occur in same RSS -- which could degrade that RSS - right ?

Thanks
Johan Guldmyr
Honored Contributor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

If you only run vraid1 then yes they are in pairs. For vraid5 in the same the disk group your data will still be available if you lose one disk per RSS.
DCESStorage_1
Occasional Advisor

Re: EVA8400 - "Disk drive failure protection" even though 2 largest 450 GB drives free space available

Thanks to you all - great responses. Things settled down after levelling, and now we got two more disks about to fail, off we go to replace those :-)