graf,
@graf@poa.st avatar

some serious database degradation is going on with the poast matrix. offlining now to swap the drives to the other racked chassis and im going to attempt to repair the database. downtime will be probably at least an hour, likely 4 or 5

splitshockvirus,
@splitshockvirus@mstdn.starnix.network avatar

@graf inb4 backplane

graf,
@graf@poa.st avatar

@splitshockvirus yeah that is what’s the cause of all of this. randomly timing out disks and dropping them from the raids. really stupid

splitshockvirus,
@splitshockvirus@mstdn.starnix.network avatar

@graf That same thing happens at my work. And it's not an easily user serviceable thing to fix.

Makes me think it'd be easier to just have all the drives directly attached to a SAS or SATA card.

graf,
@graf@poa.st avatar

@splitshockvirus this was planned. I had racked a new chassis with more or less the same config in January but we just hadn't swapped the drives over yet and last night I watched the matrix fire off millions of errors while the raid dropped two drives and for fear of database damage i immediately turned it off. glad i did. running like a top now

Personalities : [raid10] [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid1]
md125 : active raid10 sdb[4] sda[0] sdc[2] sdd[3]
      19396294656 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
      bitmap: 5/145 pages [20KB], 65536KB chunk

md126 : active raid5 sdn[1] sdp[3] sdm[0]
      1875120128 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
      bitmap: 4/7 pages [16KB], 65536KB chunk

md127 : active raid5 sde[0] sdh[4] sdf[1] sdg[2]
      29094441984 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      bitmap: 0/73 pages [0KB], 65536KB chunk
sjw,
@sjw@bae.st avatar

@graf @splitshockvirus is there any reason at all to use RAID 4 over RAID 5?

graf,
@graf@poa.st avatar

@sjw @splitshockvirus not really beyond maybe cost since you're not limited to having 3 or more disks you can theoretically do it with 2 but I would just opt for RAID5 for the kick to performance

sjw,
@sjw@bae.st avatar

@graf @splitshockvirus The fuck are you talking about? :alexjonesconfuse:

What you said is so wrong I don't even know where to begin correcting it.

graf,
@graf@poa.st avatar
sjw,
@sjw@bae.st avatar

@graf @splitshockvirus RAID 4 and 5 both have a minimum of 3 disks in an array and both allow you to lose 1 drive in an array.

graf,
@graf@poa.st avatar

@sjw @splitshockvirus okay. RAID 4 only requires two as it only has one dedicated parity disk

sjw,
@sjw@bae.st avatar

@graf @splitshockvirus yeah I guess in theory RAID 4 could be put on just two disks but that's just RAID 1 with extra steps and probably worse performance.

graf,
@graf@poa.st avatar

@sjw @splitshockvirus and that's what i was referencing. no real idea why somebody would use RAID 4 with 2 disks and not opt for RAID 1 instead, but it is a cheaper alternative. in addition when used on SSDs RAID4 actually has 15-20% faster reads than RAID 5

sjw,
@sjw@bae.st avatar

@graf @splitshockvirus
>but it is a cheaper alternative

How is RAID 4 cheaper than RAID 1?

I was not aware of the SSD thing. Why is that?

I'd like to set up a RAID 420 just for the memes but since RAID 2 requires all the drives' platters angle to be synced so I doubt I'd be able to use it on consumer hardware.

graf,
@graf@poa.st avatar

@sjw @splitshockvirus >How is RAID 4 cheaper than RAID 1

it's not. I was answering your question here: is there any reason at all to use RAID 4 over RAID 5?

that is one reason to choose it

>I was not aware fo the SSD thing. Why is that?

because RAID 4 only reads from the data disks because parity is only stored on one

BigDuck,
@BigDuck@poa.st avatar

@graf @sjw @splitshockvirus Raid Shadow Legends

graf,
@graf@poa.st avatar

@BigDuck @sjw @splitshockvirus i might go to the fancy grocery store and get a hot dog

The_Almighty_Kek,
@The_Almighty_Kek@nicecrew.digital avatar

"One Hot Dog, please!"

sjw,
@sjw@bae.st avatar

@graf @splitshockvirus would it not be faster to read from 5?

graf,
@graf@poa.st avatar

@sjw @splitshockvirus no because all data is read off data disks not parity disks. im not very good at explaining things but this page has kind of an explanation of what i mean softraid.com/raid_levels/

sjw,
@sjw@bae.st avatar

@graf @splitshockvirus interesting. Also good to know. I didn't realize raid 4 had such performance advantage on SSDs.

RedTechEngineer,

@splitshockvirus @graf @sjw
> RAID 2 requires all the drives' platters angle to be synced

wat.

sjw,
@sjw@bae.st avatar

@RedTechEngineer @graf @splitshockvirus All the platters rotate at the exact same rate. One platter rotates 20° clockwise they all do at the same time.

The angle of every platter of every drive in the array must have the same angle at all times.

It's bit level instead of block level. It just writes/reads when it's supposed to and assumes all the platters are in the correct position.

RedTechEngineer,

@sjw @splitshockvirus @graf I get that, but why? This seems needlessly complicated.

I'm also thinking about what a software raid 2 would entail.
Or raid 2 on flash.
Or raid 2 on logical volumes.

sjw,
@sjw@bae.st avatar

@RedTechEngineer @graf @splitshockvirus so RAID 2 was designed back in the 50s and 60s when computers and hard drives were very different and a single hard drive weighed 80 kg for like 5 MB.

Computers were designed very differently back then. However it was very complex and expensive to implement so it rarely ever got used. However RAID 3 wasn't nearly as complex and tedious. It has shortcomings compared to RAID 4 and RAID 5 tho.

I'm kind of surprised there is no RAID 7 since some RAID card manufacturers have their own version of it plus ZFS essentially has it.

I'm still waiting for ZFS to allow you to change raidz level.

sjw,
@sjw@bae.st avatar

@graf @splitshockvirus basically the only difference between RAID 4 and RAID 5 is that RAID 4 uses a dedicated parity drive in the array whereas RAID 5 distributes the parity data across all the drives.

RAID 5 performs better than RAID 4 as well.

splitshockvirus,
@splitshockvirus@mstdn.starnix.network avatar

@graf Right now my problem is I can't recognize my replacement drives. II get a drive letter but can't use it (factory new and tested).

And I can't determine, if the tech dropped the new drive and just lied, the port was damaged because he slammed the sled in and bent the port or if the backplane is faulty. It's the second chassis I have that's like this in this and the chassis had like 3 year uptime with no problems prior.

graf,
@graf@poa.st avatar

@splitshockvirus i guess you have no physical access to check yourself?

splitshockvirus,
@splitshockvirus@mstdn.starnix.network avatar

@graf I'd fly there if I didn't have pets to take care of and work thought it was a good use of a plane ticket and hotel. But no, everything has to be done through email or ticket remote hands. It fucking sucks.

graf,
@graf@poa.st avatar

@splitshockvirus tfw free washington state vacations

sjw,
@sjw@bae.st avatar

@graf sounds like Matrix TBH
cc @crunklord420

crunklord420,
@crunklord420@clubcyberia.co avatar

@sjw @graf I don't miss having to janny the backend.

DemonSixOne,
@DemonSixOne@poa.st avatar

@graf matrix is a pain in the testicles, thank you for all your hard work friend.

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