23 votes
Accepted

What's the difference between a "degraded" RAID 6 array and a "clean" RAID 5 array?

Besides whatever metadata the RAID controller uses, are there any differences between these two arrays (in terms of data layout, performance, reliability)? Yes. RAID5 uses a single, rotating parity ...
Zac67's user avatar
  • 11.5k
19 votes

Need to recover RAID 6 array

Recovering individual disks will only get you partial data. The "independent" means that the disk drives are not aware of each other, and can be exchanged separately. The best way to recover ...
Simon Richter's user avatar
16 votes
Accepted

RAID 6 array, one disk rebuilding?

Disks can experience temporary failures that cause them to drop out of the array but can be corrected by a system reboot or controller reset. This might really be a one-off error but I would follow up ...
doneal24's user avatar
  • 871
12 votes

Windows Storage Spaces - a useful replacement for RAID6?

Windows Parity Spaces are dog slow and (according to Microsoft) aren’t designed for anything except archive workloads. Microsoft keeps trying to improve write performance say implemented log missing ...
BaronSamedi1958's user avatar
8 votes
Accepted

Is it possible to ask ReFS to use hardware RAID6 for parity calculations?

ReFS is much like ZFS in general. They both are completely CPU oriented and do not use anything from hardware RAID controllers. Other vendors (for example StarWind with LSFS) are using hardware ...
Strepsils's user avatar
  • 5,115
8 votes
Accepted

Why does ZFS RAIDZ2 only use 2GB of data when I create a 1GB File

With two out of four disks for redundancy, you can simply double the user data: two disks store the original data and the same space is used for redundancy data on the two other disks. Parity is ...
Zac67's user avatar
  • 11.5k
7 votes

Is it possible to ask ReFS to use hardware RAID6 for parity calculations?

ReFS (and Storage Spaces Direct from Windows Server 2016 if you care) takes care indeed of some hardware offload features present in Intel Xeon CPUs (they somehow refuse to work if f.e. "popcnt" ...
BaronSamedi1958's user avatar
6 votes
Accepted

RAID 6 array much faster than my RAID 10 array?

I would recommend using deskspeed.exe to be confident about numbers which you displaying to the community. This article should help you at tunning Synology box https://www.starwindsoftware.com/...
Net Runner's user avatar
  • 6,229
6 votes

Convert linux software raid from raid5 to raid6

Make use of the --backup-file option, so in case of power loss you can continue to grow the device after a reboot and ensure no data loss. mdadm --grow /dev/md0 --level=raid6 --raid-devices=6 --...
Guggi's user avatar
  • 91
6 votes

Windows Storage Spaces - a useful replacement for RAID6?

"Windows Storage Spaces - a useful replacement for RAID6?" If by "RAID6" you mean "I hate my data and want to get to it in as slow a way as possible" then yeah, sure - we ...
Chopper3's user avatar
  • 102k
5 votes
Accepted

(Why) Does lvmraid6 need 5 drives?

This seems to be hardcoded in the source code. Here a minimum of 3 stripes is the minimum, which excludes the parity disks. So that in turn is 5 disks for a RAID6. Unfortunately the commit message ...
Thomas's user avatar
  • 4,305
4 votes

How to create degraded raid6 array using megacli

You cannot create a new RAID in a degraded state with PERC controllers. You'll need to use drives that are "unconfigured good" and presently in the system. I would recommend simply creating a RAID6 ...
JimNim's user avatar
  • 2,796
4 votes
Accepted

Which raid array will be best practices with seven 1.2 tb hdd system

First of all - backups. RAID is not a replacement. Second - I would not go with hardware raid any more. On Linux you have ZFS, on Windows you have storage spaces. Both can provide a Raid 6 level ...
TomTom's user avatar
  • 51.9k
4 votes

Why does ZFS RAIDZ2 only use 2GB of data when I create a 1GB File

The situation is (explained to get the idea, very simplified) this: Let suppose ZFS use 512MB blocks. So you store on disk 1 512MB (part one of file), on disk 2 you store next 512MB, on parity 1 you ...
Romeo Ninov's user avatar
  • 5,932
3 votes

Optimal RAID 6+0 Setup for 40+ 4TB Disks

With 4 TB 7.2k drives, I'd recommend making the subarrays as small as possible - actually, 5 drives don't really justify using RAID 6 at all. My 2c are to use RAID 10 where you can expect a rebuild ...
Zac67's user avatar
  • 11.5k
3 votes

RAID6 failed instantly and switched to RAID0 - any chance to rescue?

You had one drive down (the one you were replacing) when this happened: At this moment a strange problem occured and parted had problems accessing one of the old disk. I noticed that another ...
Leo Gallego's user avatar
  • 1,933
3 votes

Linux mdadm software RAID 6 - does it support bit corruption recovery?

All the answers above are incorrect regarding the capabilities of RAID 6. RAID 6 algorithms operate byte-by-byte just as RAID 5, and if a single byte on any one drive is corrupt, even with no error ...
Cafe Hunk's user avatar
3 votes

Need confirmation on how iSCSI RAID storage works

is the RAID level of the storage where the LUNs are stored presented to a client over iSCSI? No. The iSCSI initiator (client) sees a LUN presented as a simple drive for block storage. It can't see ...
Zac67's user avatar
  • 11.5k
3 votes

Need to recover RAID 6 array

As others said, to recover any significant amount of data from a RAID-6 array you need at least N-2 drives from the array (N being the total number of drives used in the array). From single drives you ...
wazoox's user avatar
  • 6,998
2 votes

Hardware Acceleration for MD RAID?

Some Linux-powered NAS systems offering software RAID include hardware to accelerate RAID5 and RAID6 operations. For example, several low-power NAS devices running on older ARM System-on-Chips made by ...
Emilio's user avatar
  • 21
2 votes

Linux mdadm software RAID 6 - does it support bit corruption recovery?

I would have added this as a comment but I don't have sufficient reputation; I wanted to clarify: RAID5 can DETECT bit corruption but it doesn't know which drive has the corruption without a read ...
sbingner's user avatar
2 votes

Convert linux software raid from raid5 to raid6

It seems, that everybody recommends to add one disk to the array, first, then move to RAID6, then add the remaining disks and grow the RAID6. Please keep in mind, that this causes two time-consuming ...
Kai Petzke's user avatar
2 votes

How is the HPE SSA "remove drives" command supposed to work to shrink an array?

You only have one logical drive and zero free space. That's why you can't shrink the array. There is a "consolidatespace" command that rearranges logical drives to leave free space at the ...
ewwhite's user avatar
  • 198k
2 votes

What would you call this "RAID" ? RAID 1+6?

As Chopper mentions: No. Your drive pool is duplicating the data across the same physical disks in the same RAID6 array. Meaning, you lose more than the two drives, and you will still lose all your ...
Rex's user avatar
  • 7,895
2 votes

How to Add Another Physical Drive to Adaptec maxView RAID6 Logical Drive

In case anyone else has this issue like I and the OP did, here is how I was able to get the expansion to work. I have a ASR81605, so I'm not sure if it is the same with the 7 series, but the MaxView ...
user581852's user avatar
2 votes
Accepted

Upgrading RAID6 drives with larger capacity (Best practices)

If you want to do this with no downtime, be SURE that you've got a good backup of the data beforehand. You can actually accomplish this without too much hassle using the "replace member" feature/...
JimNim's user avatar
  • 2,796
2 votes
Accepted

How to recover mdadm raid6 array? mount: can't read superblock. 8/13 drives show all drives present, 5/13 drives show only 5 drives present

HERE IS WHAT I DID, Array is back online and appears to be working. Strangely the last message was "not enough to start the array." but it did start and after a reboot the array is active and clean, ...
Jieiku's user avatar
  • 181
2 votes
Accepted

I accidently deleted the partition tables of my RAID6 drives

Just recreate the partition table exactly as it was before deleting (you can check it by using another disk as example). lsblk continue showing the partition because the disk was in use (by the raid ...
shodanshok's user avatar
  • 50.5k
2 votes

Need to recover RAID 6 array

They are independent hardware, but the data structure on them is not independent. This means that you will only get partial data if you only have parts of the array. However, RAID 6 is very fault ...
Jarmund's user avatar
  • 535
2 votes
Accepted

Upgrade from SATA to SAS: Expected speedup?

I don't expect switching to SAS HDDs to have any meaningful effect on your write speed. Rather, try to increase your stripe element size (good starting values are 256K/512K for RAID10 and 64K for ...
shodanshok's user avatar
  • 50.5k

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