Tagged Questions

ZFS is a modern filesystem originally developed by Sun Microsystems and licensed under the CDDL. An open-source fork of ZFS can be found at http://open-zfs.org/ , which is supported by ZFSonlinux.org, illumos.org and ZFS developers in the FreeBSD & MacOSX communities.

learn more… | top users | synonyms

2
votes
1answer
501 views

ZFS, NFS and Nexenta

Is this message familiar to someone ? zfs-clu-01a rpcmod: [ID 851375 kern.warning] WARNING: svc_cots_kdup no slots free zfs-clu-01a last message repeated 75220 times We have a lot of trouble ...
3
votes
1answer
237 views

“zpool create” hangs indefinitely

I have a Solaris 11.1 machine which has some disks attached to it via an expander (LSISAS2X36) through an LSI 1068 controller. The setup used to work quite decently, but as I have added another batch ...
5
votes
1answer
73 views

Is “zfs receive” an atomic operation?

Is zfs receive an atomic operation? Can a process read from or write to the receiving file system during the zfs receive operation? Can a process read any of the files in the incoming snapshot ...
3
votes
1answer
80 views

Expanding ZFS on MDRaid?

I had a 4-disk mdraid of 8.12TB with zfsonlinux's ZFS: # zpool status pool: tank state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM tank ...
4
votes
4answers
1k views

ZFS: Memory issues with dedup even though zdb -DD looks fine

I've been experimenting with ZFS on a machine with Ubuntu 12.10, 32GB RAM (non-ECC, production system will have ECC) and a 2x2TB Linux-managed RAID1 (will be moved to RAIDZ1 for production). I just ...
2
votes
1answer
254 views

XenServer Linux guest booting off iSCSI SAN (ZFS storage): Will a non-checksumming guest file system still be at risk?

We are storing files on FreeNAS 9.2 using ZFS. I love the data integrity claims made by ZFS, having randomly lost data in the past on servers using ext3, XFS, and ReiserFS that were not mistreated ...
-2
votes
2answers
341 views

Why does a failed ZFS disk still seem to work fine?

Two disks just failed in my zpool with read/write errors, so I took them out and inserted them in another host, created a zpool just with them, and filled the file system with dd if=/dev/zero ...
2
votes
1answer
53 views

Choosing a zpool size?

Is there a rule of thumb when to create a new zpool instead of expanding the current? Right now I have 100TB and can either expand with another 100TB or create an extra.
10
votes
2answers
813 views

Are consumer class hard disks okay for zfs?

I just recently bought a new server an HP DL380 G6. I replaced the stock smart array p410 controller with an LSI 9211-8i. My plan is use ZFS as the underlying storage for XEN which will run on the ...
4
votes
1answer
2k views

ZFS on Linux/Ubuntu: Help importing a zpool after Ubuntu upgrade from 13.04 to 13.10, device IDs have changed

I have updated Ubuntu from version 13.04 to version 13.10, only to discover that the SATA disks IDs have changed, and my ZFS pool now fails. On new Ubuntu 13.10 the disk IDs are now ata-* instead of ...
0
votes
1answer
501 views

Debian KVM and location for vm images different than /var/lib/libvirt/images

I have defined storage pool for VMs on ZFS: virsh # pool-dumpxml zfs <pool type='dir'> <name>zfs</name> <uuid>b2fba550-467f-8133-dee8-44ada7d0a807</uuid> ...
2
votes
1answer
92 views

Is in-memory write-cache and ZIL data both written through TXG commits?

ZFS nowadays has an interval of 5 seconds for doing TXG (Transaction Group Commits) of the in-memory write-cache.. How and after how long is ZIL data committed to the rotational media from say, an SSD ...
2
votes
2answers
176 views

zfs regular read pauses

We have a zfs file system running on openindiana with an almost purely read-only workload. Recently we have found that the io is blocked or pauses every 1 minute for around 2-3 seconds. Does anyone ...
1
vote
2answers
113 views

Can you add a different size RAIDZ1 to an exists zpool?

For example, I have a 4x2TB RaidZ1 set up right now, but I would like to add only a 3X4TB RaidZ1 in addition to it. Is there a way to do this with zdevs/another Zpool? Thanks
1
vote
1answer
221 views

Why is my RAIDZ2 pool larger than the expected size calculation?

I'm building a RAIDZ2 ZFS system, using Ubuntu 13.10 as a base system, and zfsonlinux's packages, having 6 disks dedicated to the pool data and a couple of SSD partitions to do ZIL log and L2ARC ...
1
vote
1answer
224 views

SAS IT Mode controllers and SAS Expanders

Lots of semi-related posts, but none that address this scenario. I picked up an LSI SAS1064E-IR based HP Controller. I flashed it with an -IT firmware, and things look somewhat ok. Except that I ...
4
votes
1answer
965 views

ZFS: bringing a disk online in an unavailable pool

I have a home server using FreeBSD and ZFS that has worked well for the last 5 years, and on several occasions I have successfully replace faulty disks. However, today a minor disaster has happened, ...
1
vote
1answer
44 views

Prevent NexentaStor analytics page from timing out

NexentaStor has a handy profiling interface that serves as a front to certain dtrace scripts. It's handy for monitoring realtime IOPS or I/O throughput of the appliance. Unfortunately, this interface ...
18
votes
1answer
544 views

Why are all the zpools named “tank”?

In practically every example of ZFS usage that I've seen online (including several questions here), the zpool is named "tank". Why? Is there some sort of significance to the name or is it just that ...
1
vote
0answers
103 views

NexentaStor 3.1.5-GA (community ed) won't boot from a CD

I can boot from 3.1.5-GA ISO into a VirtualBox VM. But when I boot from a bootable CD, it stops at "Grub Stage2", and then drops me into a grub rescue shell after a few seconds.. I know very well how ...
1
vote
2answers
203 views

SmartOS using ZFS and guest filesystems [closed]

If I do something like RAIDZ2 with 10 or so disks, then on guest operating systems, if I use a filesystem like ext3/4, will the guest filesystem be as safe as if it were also using ZFS? The reason I ...
2
votes
1answer
1k views

How often should I defrag ZFS pools?

I ZFS scrub once a month which takes ~24 hours for the 72TB. For what I can find about how often I should scrub is: very busy pools, once per week not so busy pools, once per month or run a scrub, ...
1
vote
1answer
305 views

ZFS: SAS v SATA - does it matter?

I understand from NEC's white paper, Silent data corruption in disk arrays, that: some SAS drives should have a "T10-DIF" feature to detect silent data corruption; whereas "There is no standard for ...
3
votes
1answer
191 views

FreeBSD 9.2 shows SATA3 drives as SATA2

I'm running FreeBSD 9.2 on an Intel S2600GZ server board with 4 Intel SSDs. Both the server board as well as the disks are SATA3 capable. However, FreeBSD seems to think they are SATA2. Nowhere in ...
2
votes
2answers
654 views

size the write cache ZFS

I would like to add a write cache to my Nexenta. I thought about using 2 SSDs in mirror with a third disc in spare. The problem is: How do I calculate the size of my array to maximize the investment ...
0
votes
1answer
363 views

zfs: zpool space map thrashing - ever fixed?

For zpools which are rather full and/or very fragmented I use to enable metaslab debugging (echo metaslab_debug/W1 | mdb -kw) to avoid space map thrashing and the resulting severe write performance ...
-1
votes
2answers
347 views

Can I remove a vdev from a ZFS pool by rolling back? [closed]

A curiosity related question: Can a VDEV be removed from a ZFS pool by undoing the last pool transactions (zpool import -F) or rolling back to an earlier snapshot?
2
votes
2answers
891 views

iSCSI: LUNs per target?

My question relates specifically to ZFS/COMSTAR but I assume is generally applicable to any iSCSI system: Should one prefer to create a target for every LUN that you want to expose? Or is it good ...
2
votes
1answer
970 views

ZFS Recover from Faulted Pool State

I have a six disk ZFS raidz1 pool and had a recent failure requiring a disk replacement. No problem normally, but this time my server hardware died before I could do the replacement (but after and ...
2
votes
1answer
436 views

Using ZFS or XFS on a Xen guest running Linux

Background: I'm investigating the viability of using a filesystem other than ext3/4, with the ability to run snapshots for backup and rollback purposes. The servers under consideration are mailbox ...
3
votes
1answer
94 views

ZRAID1 pool size bigger than expected

I have 3x 4TB drives for a ZRAID1 config (single parity drive) After running zpool create data zraid1 sdb sdc sdd I have a volume that's 10.9T in size, which is what I would expect from a stripe ...
-4
votes
2answers
335 views

Hardware RAID0: what happens when a drive fails?

With a hardware-based RAID0, what happens when a drive fails? For example, on brand name servers like HP DL120G7 with HP P410, when running FreeBSD on a zfs with a zpool mirror, or DragonFly BSD with ...
12
votes
5answers
3k views

ZFS best practices with hardware RAID

If one happens to have some server-grade hardware at ones disposal, is it ever advisable to run ZFS on top of a hardware-based RAID1 or some such? Should one turn off the hardware-based RAID, and run ...
2
votes
3answers
113 views

zfs on a single device: what happens when a file is corrupted?

It is written everywhere that ZFS is helpful even if you only have one physical device, because it will tell you about data corruption due to bit decay and such. However, can it actually address such ...
0
votes
2answers
702 views

ZFS: 3 devices: what's the difference between mirror and raidz2?

It would seem like with 3 devices, it's possible to configure a ZFS pool with either mirror or raidz2 mode. What's the difference in performance and reliability? (In regards to reliability, I'm ...
4
votes
2answers
886 views

Can XFS or GlusterFS replace my ZFS needs?

Right now I have a FreeBSD hosts with ZFS and NFSv4. It is replicated to another FreeBSD box for backup purposes. The ZFS features that are important to me are software RAID6 snapshots, or some ...
4
votes
1answer
255 views

Is there a way to limit the network bandwidth / filesystem use per user over NFS on a Solaris 10 file server?

We have a large file server running on Solaris 10 and about 200 computing nodes running on Ubuntu. The nodes access the file server over NFS. The load gets larger and larger over time. Is there a way ...
11
votes
1answer
405 views

Force update checksum on zfs?

I recently changed the checksum property on one of my non-duplicated zfs filesystems to sha256 from on (fletcher4) to better support the sending of duplicated replication steams, as in this command ...
3
votes
1answer
125 views

Replacing a recovered hard disk in a ZFS pool

I have a pool that is in UNAVAL status (" One or more devices could not be opened. There are insufficient replicas for the pool to continue functioning.") due to a recent disk failure. I'm planning ...
2
votes
1answer
214 views

What kind of “volume/storage management” has the largest support/feature set these days? [closed]

(DISCLAIMER: This is "time bound" as probably every other question, I just point it out now instead of implicating it) part of reviewing a few basic decisions for our infrastructure is once again the ...
2
votes
2answers
456 views

Increase space of ZFS pool over iSCSI SAN, online

I have an iSCSI volume of 96GB on SAN, which has ZFS pool implemented on it. i have resized the size of SAN volume from 96 to 120GB, but the zpool list only shows the old space (96GB). how to achieve ...
1
vote
1answer
485 views

cannot create zfs pool on iscsi multipath drives

I have a disk on iSCSI SAN, which i have mounted on my server through multipath. when i run the command to create zfs pool using zpool create -f zfs-data /dev/sdc or zpool create -f zfs-data ...
1
vote
2answers
863 views

High load with low CPU usage and low IO usage on Solaris with ZFS and MySQL

I have a Solaris 10 x86_64 system running MySQL 5.5. Under heavy usage times, we're getting very slow responses from the database: slow queries running into minutes that normally return in sub-second ...
5
votes
2answers
420 views

What to call ZFS vdev that won't change?

I've got an Ubuntu (13.04) Desktop with ZFS support thanks to the PPA zfs-native/stable. Everything was working really well. I created a RAID-Z1 pool called inground with the following command: ...
6
votes
2answers
233 views

How can you find the parent snapshot of a zfs clone?

I made a clone of zfs filesystem that has a number of snapshots. I also have several replicated copies of the filesystem. How can I find which filesystem/snapshot a clone is attached to? (Seems ...
3
votes
3answers
1k views

How to run a command once a ZFS scrub *completes*?

I would like to use cron to schedule periodic scrubs of my ZFS pool, and at some reasonably short time after the scrub finishes, email a status report to myself. The purpose of this is to catch any ...
5
votes
2answers
130 views

ZFS Equivalent of lvdisplay snap_percent

I've been using LVM snapshots for backing up MySQL databases. FLUSH TABLES WITH READ LOCK is issued and then lvcreate --snapshot --size 4G etc. Because the database is live while the snapshot is ...
0
votes
2answers
7k views

Expanding a FreeNAS RAIDZ Pool

I am building a ZFS data server using FreeNAS. I have enough hard disk space (4x2TB) for a few years, but if down the road I want to expand this out can i build another 4xHD pool? Would i need ...
2
votes
2answers
66 views

ZFS online disk migration

I'm wondering if ZFS can handle the following. Say I have FreeBSD installed on a zpool with two physical 500GB disks in a mirrored setup. These form the root partition, so only a maximum of 20GB is ...
2
votes
1answer
181 views

Best practices on VM disk management

I'm replacing two old rack servers with a new one that has plenty of power to take over the functionality the current servers. The server is a 4U rack mount with 16 3.5" SAS drive bays, two 2.5" bays, ...