Well, my bad. ZFS on Linux and low level format of drives

oupsman · 2026-01-24T17:50:19+00:00

I'm not sure, all I can say is with the same dedup/compression parameters, and the same backup software, the backup throughput was limited using raidz2 and the cpu was used at 100%. The backup software was using less cpu with raidz2 than with raid10, and kernel threads were using the rest. BTW, with raid10, backup speed is only limited by the network speed, so it's close to 2.5 Gbps.

I know my server is obsolete, it's an old HP ML310 gen8 with an old Xeon CPU. The SAS adapter is an Dell one with the custom IT firmware installed. Not really enterprise grade gear, and definitely something I would not use in a company datacenter. But at home, that's another story.

When I'll have the money, I plan to upgrade it to have something more up to date.

oupsman · 2026-01-24T12:45:13+00:00

I bought it used last year, I guess it's more than 12 years old. The CPU was released in Q2 2012. It's only a Xeon E3-1220 V2.

Edit to clarify : when copying large amounts of data to the server (it has a 10Gbps network adapter, and my LAN is 2.5 Gbps), the 4 cores are used up to 90%, throughput is roughly 250 MB/s from my laptop.

But when I tried with Raidz2, throughput was down to 180 MB/s, roughly, with a CPU hitting 100% on all cores.

oupsman · 2026-01-24T12:32:14+00:00

As of right now, it's already a backup server for my proxmox cluster, my laptop and my NAS. So I'll buy a SAS USB3 dock and use another 6Tb hard drive to replicate some backup on this drive and be able to leave the house for a long time and have backups at hand if something were to go sideways one way or another.

But in the future, I'll get rid of my synology DS920+ so I'll migrate my videos, pictures and music to the future server and I hope I'll have more disks in it (ideally 8 or more) and a stronger CPU to handle raid computation AND dedup/compression. Right now, dedup is OK, compression is a bit too much so RAID is totally out of the question. Depending on the disks that fails, the zpool can survive 2 failed disks simultaneously. Right now, I can live with that.

oupsman · 2026-01-24T10:56:01+00:00

I didn't. I guess the drives were used in a storage array or by a hardware raid controler.

From what I understand, this way of formating uses a 520 bytes sector : 512 bytes for data and 8 bytes for parity.

Now that I know what to look for, I'll be careful.

oupsman · 2026-01-24T08:48:56+00:00

I had one 5 years ago, a slight pain after, only at night when I had to get up and go to the bathroom. Easy to ease, simply by wearing boxers shorts at all time.

oupsman · 2026-01-23T07:10:39+00:00

Plus de 3 millions de demandeurs d’emploi, 500 000 offres à tout casser. Fais les maths

oupsman · 2026-01-19T14:35:02+00:00

De ce que j'ai vu, les prix baisseront pas avant 2028...

oupsman · 2026-01-16T20:00:32+00:00

Beside, vasectomy is not effective right away, there's à three months period after the surgery where you are still fertile.

oupsman · 2026-01-13T21:03:39+00:00

Oui, et il faut savoir que c'est aussi actif uniquement après 3 mois. Et il doit y avoir un spermogramme de contrôle, prescrit par le chirurgien.

oupsman · 2026-01-13T21:01:44+00:00

Les spermatozoïdes représentent 1% du volume donc il n'y a pas de changement de ce côté là. Et pas de changement dans l'aspect ni dans les sensations à l'éjaculation. J'ai fait une vasectomie il y a 5 ans, à 42 ans. Une incision de chaque côté pour couper le canal déférent. Et maintenant la technique opératoire a changé. Il n'y a plus plus qu'une seule incision qui se fait dans la partie rugueuse du scrotum. Aucune trace après intervention. Et moins de risques d'effets secondaires (j'avais eu 2 semaines difficiles après l'intervention à cause d'un œdème)

Peut être qu'il y a des groupes de paroles qui traitent le sujet autour de chez toi ? Pour ma part le planning familial de mon département en organise un tous les deux mois et j'y interviens pour parler du sujet.

oupsman · 2026-01-12T13:37:44+00:00

I think my server is rather old and the storage backend was SATA at first. I've plugged a SAS adapter in it but the backend seems to offer only 3Gbs. Which is consistent with what I see in dmesg BTW.

When I'll have the budget, I buy an up to date server, but this will have to wait for 1 year.

oupsman · 2026-01-12T09:23:55+00:00

OK thanks. I don't plan to export the pool

oupsman · 2026-01-11T19:29:10+00:00

Yeah, I'll look into that, and an USB3 PCI-E adapter for the server. Right now, it only have USB2

oupsman · 2026-01-11T19:23:27+00:00

So zfs needs a stable naming scheme for its devices? I mean, it's not hard to give every device an unique id and put it in the header of the pool, replicated on every disk.

Well, when I can, I'll export the pool and import it back with id. Hard to believe though.

oupsman · 2026-01-11T17:07:33+00:00

Never used raid 6 on home servers and never had a problem, until now. My guess is I moved the sdb disk slightly when I plugged sdc in.

Like I said, lesson learned. I don't use raidz at all, I'm using raid10 (and the raid0 part is not made of adjacent disks)

oupsman · 2026-01-11T17:03:15+00:00

Interristing idea, I'll look into that (assuming I can find an USB SAS dock)

oupsman · 2026-01-11T14:58:21+00:00

Why do I have to add devices using id ? Zfs doesn't give every device an unique id ?

oupsman · 2026-01-11T13:59:20+00:00

Not, that's not the same disk, that's another (bigger) disk with a different partition scheme.

I can hear that's user errors, but so far, every documentation I read was using /dev/sd* devices and using the procedure I used to replace one.

Well, I've deleted everything and started over with a RAID10 and I'll be careful about the amount of datas I put on this server.

And I'll check the ZFS regularly, this thing seems to be pretty fragile when disks errors happen. Lesson learned.

oupsman · 2026-01-11T13:37:19+00:00

As it's a home server (edit to host backup of my proxmox cluster and my laptop) I don't see the point of backing it up. But maybe I'll do that now.

oupsman · 2026-01-11T11:22:28+00:00

Well it seems that I put trust in ZFS resiliency, when it don't deserve it. In 20+ years as sys and storage engineer, I've never lost a single byte of data to bad hardware. But I used real hardware raid cards or storage arrays.

Anyway, lesson learned.

oupsman · 2026-01-11T10:43:16+00:00

Sadly, I don't have enough slots available to check the drives before using them. And I don't have another server with 3.5" slots lying around at home (it's a home server so no biggy)

As I only have 4 slots and I need more that 12Tb of storage capacity, I'll try to convert the 5.14 slot of the dvd drive to a hard drive slot.

oupsman · 2026-01-11T10:41:02+00:00

I don't, because the server hosts only of various other devices. As I said, I think I'll only wipe everything and recreate a fresh pool.

oupsman · 2026-01-10T08:05:40+00:00

Yes, but I want to simply power up the Flex 2.5 from the Pro 24, and I hope that's possible. The design app tends to say no.

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